No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Human Versus Animal: Contrasting Decomposition Dynamics of Mammalian Analogues in Experimental Taphonomy
Abstract
Taphonomic studies regularly employ animal analogues for human decomposition due to ethical restrictions relating to the use of human tissue. However, the validity of using animal analogues in soil decomposition studies is still questioned. This study compared the decomposition of skeletal muscle tissues (SMTs) from human (Homo sapiens), pork (Sus scrofa), beef (Bos taurus), and lamb (Ovis aries) interred in soil microcosms. Fixed interval samples were collected from the SMT for microbial activity and mass tissue loss determination; samples were also taken from the underlying soil for pH, electrical conductivity, and nutrient (potassium, phosphate, ammonium, and nitrate) analysis. The overall patterns of nutrient fluxes and chemical changes in nonhuman SMT and the underlying soil followed that of human SMT. Ovine tissue was the most similar to human tissue in many of the measured parameters. Although no single analogue was a precise predictor of human decomposition in soil, all models offered close approximations in decomposition dynamics.
... As an abiotic environmental taphonomic agent, soil plays an important role in human decomposition and preservation. To better understand the bilateral relation between soil and buried human bodies, studies have been conducted over the years using human remains which have been donated to science [23][24][25], exhumations carried out in cemeteries [26,27], and experiments performed with non-human animals used as proxies [25,[28][29][30]. Although forensic experts can analyse a long list of physical, chemical, and biological soil properties, the authors have summarized and discussed eight specific proprieties as presented in Table 2. ...
... As an abiotic environmental taphonomic agent, soil plays an important role in human decomposition and preservation. To better understand the bilateral relation between soil and buried human bodies, studies have been conducted over the years using human remains which have been donated to science [23][24][25], exhumations carried out in cemeteries [26,27], and experiments performed with non-human animals used as proxies [25,[28][29][30]. Although forensic experts can analyse a long list of physical, chemical, and biological soil properties, the authors have summarized and discussed eight specific proprieties as presented in Table 2. ...
... Beef (Bos taurus) Cadaveric decomposition appears to increase soil electrical conductivity in sandy soil with a subsequent decline of it. [25] Human (Homo sapiens) ...
Cemeteries from the European Romantic period (18th–19th centuries) are often compared to small cities that hold memories, art, and history. Portuguese public cemeteries were first established in 1835 and became an interesting combination of fauna, flora, and monumental sculptures to mourn the dead at a location outside the limits of the city. Over the past 187 years, laws have been created and amended taking into consideration the needs of the population and the scientific knowledge available at each time point in history. Nevertheless, cemeteries have long been struggling with the lack of burial space which has been emphasised during the two years of the COVID pandemic. This work aims to review the development of Portuguese public cemeteries since their establishment, highlighting the imposed measures for the inhumation and exhumation of the deceased. It will also discuss the importance of soil as an abiotic agent, focusing on eight specific soil properties and their significance on the characterisation of graves. It is expected that a better understanding of the impact of soil on human taphonomy supports the role of city halls in managing public cemeteries, particularly the lack of burial space.
... There is a growing body of literature documenting the effects of vertebrate decomposition on soil in these hotspots, which include a wide range of abiotic, biotic, and biotically-induced parameters. Soil chemistry studies have revealed temporally-associated changes in pH [2][3][4][5][6][7][8][9][10][11], electrical conductivity [5,8,10,11], soil oxygen levels [2], enzyme profiles [2], fatty acid residues [12], steroid fingerprints [13], and fluxes in carbon and nitrogen speciation pools [2,3,[5][6][7][8]10,11]. High-throughput sequencing has been used to examine bacterial (and to a lesser extent, fungal) community composition and successional patterns [6,7,[14][15][16][17][18][19]. However, in comparison with soil chemistry and microbial studies, targeted examination of multicellular soil faunas, particularly microfaunal members of the soil food web that function as secondary consumers of these resources, have received the least attention [but see [20][21][22][23][24]. ...
... There is a growing body of literature documenting the effects of vertebrate decomposition on soil in these hotspots, which include a wide range of abiotic, biotic, and biotically-induced parameters. Soil chemistry studies have revealed temporally-associated changes in pH [2][3][4][5][6][7][8][9][10][11], electrical conductivity [5,8,10,11], soil oxygen levels [2], enzyme profiles [2], fatty acid residues [12], steroid fingerprints [13], and fluxes in carbon and nitrogen speciation pools [2,3,[5][6][7][8]10,11]. High-throughput sequencing has been used to examine bacterial (and to a lesser extent, fungal) community composition and successional patterns [6,7,[14][15][16][17][18][19]. However, in comparison with soil chemistry and microbial studies, targeted examination of multicellular soil faunas, particularly microfaunal members of the soil food web that function as secondary consumers of these resources, have received the least attention [but see [20][21][22][23][24]. ...
... There is a growing body of literature documenting the effects of vertebrate decomposition on soil in these hotspots, which include a wide range of abiotic, biotic, and biotically-induced parameters. Soil chemistry studies have revealed temporally-associated changes in pH [2][3][4][5][6][7][8][9][10][11], electrical conductivity [5,8,10,11], soil oxygen levels [2], enzyme profiles [2], fatty acid residues [12], steroid fingerprints [13], and fluxes in carbon and nitrogen speciation pools [2,3,[5][6][7][8]10,11]. High-throughput sequencing has been used to examine bacterial (and to a lesser extent, fungal) community composition and successional patterns [6,7,[14][15][16][17][18][19]. ...
Decomposition of vertebrate remains is a dynamic process that creates localized soil enrichment zones. A growing body of literature has documented effects of vertebrate decomposition on soil pH, electrical conductivity, oxygen levels, nitrogen and carbon speciation, microbial biomass, and microbial successional patterns. However, relatively few studies have examined the microfaunal members of the soil food web that function as secondary consumers, specifically nematodes. Nematodes are often used as indicators of enrichment in other systems, and initial observations from vertebrate decomposition zones have indicated there is an effect on nematode communities. Our goal was to catalog decomposition-induced nematode succession and changes to alpha, beta, and functional diversity, and identify potential indicator taxa associated with decomposition progression. Six adult beaver (Castor canadensis) carcasses were allowed to decompose in a forest ecosystem for one year. During this period soil temperature, moisture, and electrical conductivity were monitored. Soils samples were taken at two depths in order to assess nematode community dynamics: 30-cm cores and 1-cm interface samples. Nematode abundance, alpha, beta, and functional diversity all responded to soil enrichment at the onset of active decay, and impacts persisted through skeletonization. After one year, nematode abundances and alpha diversity had recovered to original levels, however both community membership and functional diversity remained significantly altered. We identified seven indicator taxa that marked major transitions in decomposition progression. Enrichment of Rhabditidae (B1) and Diplogasteridae (B1) coupled with depletion in Filenchus (F2) characterized active and advanced decay prior to skeletonization in both cores and interface soils. Enrichment of Acrobeloides (B2), Aphelenchoides (F2), Tylencholaimidae (F4) and Seinura (P2) occurred during a narrow period in mid-skeletonization (day 153). Our study has revealed soil nematode successional patterns during vertebrate decomposition and has identified organisms that may function as indicator taxa for certain periods during decomposition.
... Cadaveric materials introduced into soil beneath the carcass or cadaver impact its chemistry [12,15,16,27,28]. A distance of 5 m from the carcass, based on our study, is too close to the carcass for it to be reliably used as a control soil and the major reason for collecting additional control soils from a different location, upslope from the decomposition site in 2014. ...
... Factors that induce ammonium volatilization include higher soil temperature and pH and lower moisture content. Stokes et al. [27] suggested that at a higher soil pH, NH 4 -N is more readily volatilized and lost to the atmosphere. Differences in NH 4 -N for field moist compared to oven or air-dried soils prior to extraction highlights the difference in NH 4 -N concentration and suggests that research should be conducted and standard operating procedures produced. ...
... Thus, scavenging by vertebrates reduces NH 4 -N concentrations in soil compared to a carcass protected by scavenging [16] illustrating the transfer of nutrients in the food chain. Our study illustrates the movement of NH 4 -N to invertebrates in the food chain; our NH 4 -N 14-day, The rapid decrease in NH 4 -N after its initial peak is likely due to a) translocation down the soil profile although this is not observed until after 400 d in a clay soil [12], b) nitrification of the ammonium ions by aeration [36] or c) differences in soil pH [27]. ...
Under normal circumstances, insects such as blow flies will oviposit and larvae will colonize
a carcass as soon as possible. However, insect colonization on a carcass may be delayed due to the effects of wrapping, shallow burial, addition of lime derivatives to mitigate scavenging and odor, or extreme weather. The impacts of delayed insect colonization on carcass decomposition and its subsequent effect on soil chemistry profiles have not been examined to date. The objectives of this study were to determine soil chemistry dynamics associated with porcine carcasses experiencing delayed insect colonization for 7-d or 14-d. Soil chemistry profiles such as ammonium-N (NH4-N), orthophosphate-P (PO4-P) and dissolved organic carbon (DOC) were significantly different among treatments; insect inclusion (immediate access of blow fly colonization on porcine carcasses), 7-d insect exclusion and 14-d insect exclusion (blow fly access was delayed up to 7-d and 14-d). Furthermore, significant differences of soil chemical profiles were detected between days of decomposition and soil regions. Soil moisture, NH4-N, PO4-P and DOC were significantly higher when insects were excluded from the porcine carcass suggesting loss of tissue from larval feeding reduced the mass of nutrients entering the soil. This study provides useful information for forensic science in cases where insect colonization is delayed for a period of time post-mortem and soil chemistry in the cadaver decomposition island is considered for estimating post-mortem interval.
... Therefore, it is important to consider the benefits and limitations of the utilisation of animals as human analogues in taphonomic study. In an experiment conducted by Stokes et al. (2013), the mass loss of skeletal muscle tissue from Bos Taurus (cattle), Sus scrofa (domestic pig) ...
... This is because 99.67% of insects captured on the pig and human cadavers were common to both species. Human and pig cadavers also share similar soil electroconductivity (Stokes, Forbes, and Tibbett, 2013). Although Sus scrofa have been utilised in many taphonomic studies over the years (Archer, 2004;Haefner et al., 2004;Sutherland et al., 2013;Matuszewski et al., 2014) there have been various studies suggesting a deterrence of the substitution of human cadavers for animals in taphonomic research due to the difficulty when transferring the results to real-time forensic cases. ...
... Although Sus scrofa have been utilised in many taphonomic studies over the years (Archer, 2004;Haefner et al., 2004;Sutherland et al., 2013;Matuszewski et al., 2014) there have been various studies suggesting a deterrence of the substitution of human cadavers for animals in taphonomic research due to the difficulty when transferring the results to real-time forensic cases. Although Stokes et al. (2013), found that pig carcasses could be closely compared to human cadavers, they stated that care must be taken when interpreting results. They concluded that with further study it may be possible to use animal models as accurate human analogues for specific measurements. ...
The purpose of this study was to explore whether there is a relationship between the body size of a cadaver and the rate of decomposition. The study utilised two populations of pig carcasses, the individual masses of the smaller population ranged between 6.6 - 7.1 kg and the larger population ranged between 12.3 - 16.1 kg. The TBS was documented using the scale proposed by Megyesi et al. (2005). The TBS was recorded each week by three independent persons to ensure inter-rater reliability was present due to the subjectivity of the scoring system. Initially, a 3D scanner was used to collect point-cloud data of the cadavers. The technique intended to take non-destructive measurements of the cadavers. However, the 3D scanner available was not compatible to this study so this method was terminated, and the mass of the cadavers were recorded at each interval instead.
... Most research is commonly conducted on pigs, rabbits, mice, or rats, either dealing with the carcass as a whole or select anatomic sections, for example, trotters. The choice of these is often dependent on the cost, availability, and scale of the experiment (Stokes et al., 2013). Unfortunately, however, this has resulted in questions with regards to transferability when much of the data collected from studies conducted on nonhuman remains are utilized in death scene investigation. ...
... Unfortunately, however, this has resulted in questions with regards to transferability when much of the data collected from studies conducted on nonhuman remains are utilized in death scene investigation. Turner and Wiltshire (1999), Notter et al. (2009), andStokes et al. (2013) have all recorded disparities in outcomes from the use of pigs as human analogs with the latter revealing that none of the analogs utilized had similar results when measuring decomposition to those obtained when testing on human remains in a subsurface soil environment. Research looking at the use of pigs and rabbits in comparison to human cadavers across different seasons has showed that their use as analogs does not yield the transferable results originally anticipated (Dautartas et al., 2016). ...
... Many ethical issues are raised when considering the use of human remains for research purposes. Thus any experimentation that makes use of cadavers must be highly regulated (Stokes et al., 2013). Existing legislation in the United Kingdom prevents any form of taphonomic experimentation to be performed on human tissue, as governed by the Human Tissue Authority (HTA), hence there is a significant push from academics in the field to begin discussions with the HTA surrounding the current legislation. ...
The topic of taphonomy is discussed with a contemporary overview and focus on its application in a forensic context. The stages of decomposition are detailed with their characteristic biological and chemical changes highlighted. Some areas of environmental influence are addressed through deliberations on how they disrupt the ‘normal’ decay process. Examples include arrested decay such as mummification and adipocere formation. Also, discussions are made on differences observed with surface, subsurface and aquatic depositions. The chapter presents a strong focus on the usefulness of taphonomic analysis in the determination of the time-since-death and considers the feasibility and application of some recommended methods such accumulated degree days, cooling charts, soil chemistry and total body scoring. The development of taphonomic research and requisite facilities are addressed with discourse on the ethics and legislation currently governing studies using human remains and the future of the discipline.
... Irrespective of subdiscipline, all forensic science studies intended to inform real crime investigations on human remains, including determining PMI, PMSI, and PBI, must follow specific ethical guidelines. Therefore, and as posited by many researchers (e.g., Benbow and Pechal, 2017;Cockle and Bell, 2015;Finley et al., 2016;Hyde et al., 2017;Stokes et al., 2013), the ideal for all forensic research is to use human cadavers, where the studied decomposing material generates information and knowledge that is directly relevant to PMI, PMSI, and PBI calculations, and clandestine burial location in real crime scenes. Nevertheless, ethical and legal frameworks, including the sourcing of human cadaveric materials, parallel with historical and current policy statements, mean that this ideal is not always feasible in parts of the world. ...
... Specifically, and since suids are often the mammalian surrogate of choice, what significance should be attached to the particular species used regarding Sus scrofa domesticus Erxleben and Sus scrofa Linnaeus ( Payne, 1965)? So, are all species the same and equal ( Schoenly et al., 2007;Stokes et al., 2013)? Finally, and as discussed expansively in Chapter 6, analyses of microbial community ecological succession for potential forensic investigations can adopt components of a cadaver or human proxy instead of the whole animal. ...
... In the absence of the requisite ethical and legal infrastructure, thanatomicrobiomebased forensic ecogenomics will probably continue to rely on suids, which as omnivores are expected to have a similar gut microbiota, fat distribution, and minimal hair coverage as humans ( Howard et al., 2010;Swann et al., 2010). Although they resemble humans sufficiently as whole organisms, Stokes et al. (2013) demonstrated that using parts of S. scrofa may render the decomposition process dissimilar to that of human cadavers. Briefly, the researchers investigated the decomposition of skeletal muscle tissues from different animals and reported that ovine tissue shared most of the measured parameters in common with human tissue. ...
Although domestic pigs (Sus scrofa domesticus Erxleben) are generally accepted as appropriate human taphonomic proxies, taphonomic studies have used a wide variety of mammalian analogues. These include, among others, cattle (Bos taurus Linnaeus), sheep (Ovis aries Linnaeus), mice (Mus musculus Linnaeus) and brown rats (Rattus norvegicus Berkenhout), and their respective laboratory-reared subspecies. Furthermore, organs/tissue types from different species have been used, both with and without molecular analysis, notably in forensic entomology studies. The relevance, applicability and limitations of common, disparate and novel approaches must, therefore, be deliberated within the multi-disciplinary forensic ecogenomics and related forensic sub-disciplines. The implications of differences in animal model species, their organs/tissues and related parameters are explored and assessed to inform protocol standardization and knowledge transferability to often restricted cadaver-based analyses. The ultimate goal is potential validation and adoption of forensic ecogenomics in real crime scene toolkits in the determinations of postmortem, postmortem submersion, and postburial intervals.
... However, such experimental work on exposed humans is not feasible in many other countries, including Switzerland [15]. Therefore, taphonomic studies on exposed human remains in Europe are often performed retrospectively from medico-legal casework or with various non-human species as substitutes, in particular, domestic pigs (Sus scrofa domesticus) [16][17][18][19][20]. Despite anatomical and physiologic differences between humans and pigs [16,21,22], domestic pigs are often studied as proxies because of their comparable skin, body composition, weight range, physiology, and gut microbiota [16,20,21,[23][24][25]. ...
... Therefore, taphonomic studies on exposed human remains in Europe are often performed retrospectively from medico-legal casework or with various non-human species as substitutes, in particular, domestic pigs (Sus scrofa domesticus) [16][17][18][19][20]. Despite anatomical and physiologic differences between humans and pigs [16,21,22], domestic pigs are often studied as proxies because of their comparable skin, body composition, weight range, physiology, and gut microbiota [16,20,21,[23][24][25]. ...
The total body score (TBS) is a visual scoring method to scale the succession of decomposition stages. It compares decomposition between cadavers, to connect it with external taphonomic factors and estimate the post-mortem interval. To study decomposition in various climatic environments, pigs are often used as human proxies. Currently, there is one TBS system by Keough et al. (J Forensic Sci. 2017;62:986) for surface-deposited domestic pigs, coming from South Africa. Our study aims to evaluate this method and analyze porcine decomposition in Central Europe to inform forensic research and casework. We conducted an experiment studying six 50 kg pig carcasses in a temperate Swiss forest. Three observers documented decomposition patterns and rated the decomposition stages from photographs based on the por-cine TBS model by Keough et al. (J Forensic Sci. 2017;62:986). We documented discrepancies between the carcass decomposition of our specimens and those in the South African study, especially related to the high insect activity in our experiment. Furthermore, we noted factors complicating TBS scoring, including rainfall and scavengers. The agreement between TBS observers from photographs was in the highest agreement category apart from one "substantial agreement" category. Our study is the first in Europe to systematically test the Keough et al. (J Forensic Sci. 2017;62:986) method. The results evidence that regional adaptations are required to be applicable for other environments. We present a modified approach based on experimental observations in a Swiss temperate forest. The identification of regional decomposition patterns and drivers will inform future taphonomy research as well as forensic case-work in comparable contexts in Central Europe.
... Decomposed bodies change the physical and chemical properties of the soil they interact with through the release of nutrients and energy [22]. This interaction can possibly alter soil pH, electrical conductivity, and nutrient levels [23,24] which produce an odor that is detectable by properly trained HRD dogs. The odor can remain in the soil or on the surface long after the remains have completely decomposed, and no bone is left [25]. ...
... The odor can remain in the soil or on the surface long after the remains have completely decomposed, and no bone is left [25]. Furthermore, multiple studies indicate that HRD dogs can distinguish between decomposing human cadavers and those of other animals [24,26] since each animal cadaver is composed of a unique set of volatile organic compounds (VOCs) that produce a unique odor [12]. There is some overlap in VOCs found in different animal cadavers, but each species has a unique set. ...
The Battle of Kettle Creek was the only major victory for U.S. forces in Georgia during the American Revolutionary War that took place on February 14, 1779. Around 50 loyalist prisoners were subsequently, and controversially, convicted of treason and 5 hanged. The battlefield site was only identified in 2008 and the land was purchased by the American Battlefield Trust in 2018. This article aims to present results from a forensic archaeological search to answer two questions: (1) was it possible to identify the burial ground(s) for site preservation from this historic battlefield site; and (2), were the fallen soldiers from the battle buried in a mass grave or in individual interments? Search methods included a phased investigation approach of a desk study, then ground searches involving cadaver dogs, geophysics (GPR), and subsequent forensic archaeological excavation and soil analysis (specifically mtDNA and VOC extractions) to recover possible trace evidence of human burials. Results suggest the main battlefield burial area was able to be identified, with 24 cadaver dog alert locations, geophysical and soil anomalies suggesting individual burials where fallen soldiers were interred. Archaeological excavation found contemporary battlefield artifacts, and although human remains were not recovered, the soil analysis showed the presence of mtDNA in these locations. Despite the difficult ground search conditions due to the large search area, 200 + years age of burials, and limited remains, such a focused search strategy has been proven to be an effective approach to detect other historic battlefield burial sites.
... Decaying carcass/cadaver on land environment Decomposer-sphere effects are cadaver specific, as porcine, bovine, lamb and human cadavers can promote decomposer-spheres of unique pH, mineralized carbon, nitrogen, phosphate and potassium (Stokes et al. 2013) 3A). Additionally, when considering the decomposersphere, eco-evolutionary forces are at play, including drift (i.e., stochastic change in relative abundance), dispersal (i.e., movement in space), and response to selection (i.e., deterministic change in abundance due to fitness) (Nemergut et al. 2013). ...
... In comparison to plant material, decomposerspheres that arise from animals tend to result in an increase in mineralized carbon and nutrients (Stokes et al. 2013). The environmental medium and the amount of organic content (i.e., carcass size) are important for determining the rate of spill-over from decomposer spheres to the background environment Fig. 3 Examples of both the decomposer-sphere concept and spill-over. ...
Decomposition is pivotal for the cycling of nutrients and carbon, but this process also results in the release of byproducts and chemical compounds that may transiently affect the resident community through space and time. The resident community includes microbes and invertebrates that may be influenced by transformed dead material, whose degradation can promote distinct chemical environments or decomposer-spheres. The decomposer-sphere is a unifying concept that features transient chemical signals (e.g., organic acids, polyphenols, oxidation state, and methanogenesis) that can alter the chemical environment, thereby leading to shifts in local community composition (e.g., microbes, invertebrates, and scavenging animals). The decomposer-sphere can be small, as it can be generated by leaf litter or small animals, but it can also extend many meters and beyond if generated by fallen trees or large animals. The current article aims to conceptualize how the decomposer-sphere affects resident microbial communities across study systems (i.e., cadavers, dead animals, plant litter) and to provide insight into a broad concept that is not as widely discussed when describing decomposition.
... For example, change in soil pH is highly variable between studies. While Perrault and Forbes (6) and Aitkenhead-Peterson et al. (7) reported decreased pH in decompositionimpacted soils, other studies have reported increased pH (3,(8)(9)(10). It is unknown why differences in soil pH response are observed between sites and studies. ...
... We found that soil pH response varied between individuals, with soil pH increasing for individuals with BMI ,18.5 and decreasing for those with BMI .18.5. Variable pH response is in accordance with previous vertebrate decomposition studies in terrestrial ecosystems, where some studies report increased soil pH (1,3,9), while others report decreased pH (6,8,10). Fancher et al. (2) observed both increased and decreased soil pH within the same study assessing human decomposition. ...
ABSTRACT Microorganisms are key decomposers of vertebrate mortalities, breaking down body tissues and impacting decomposition progress. During human decomposition, both extrinsic environmental factors and intrinsic cadaver-related factors have the potential to impact microbial decomposers either directly or indirectly via altered physical or chemical conditions. While extrinsic factors (e.g., temperature, humidity) explain some variation in microbial response during human decomposition in terrestrial settings, recent work has noted that even under the same environmental conditions, individuals can have different decomposition patterns, highlighting the potential for intrinsic factors to impact microbial decomposers. The goal of this study was to investigate the effects of several intrinsic factors (age, sex, diseases at time of death, and body mass index [BMI]) on chemical and microbial changes in decomposition-impacted soils. In a field study conducted at the University of Tennessee Anthropology Research Facility, soils were collected from the decomposition-impacted area surrounding 19 deceased human individuals through the end of active decomposition. Soil physicochemical parameters were measured, and microbial (bacterial and fungal) communities were assessed via amplicon sequencing. BMI was shown to explain some variation in soil pH and microbial response to human decomposition. Hierarchical linear mixed (HLM) effects models revealed that BMI category significantly explained variation in pH response within decomposition-impacted soils over time (HLM F = 9.647; P
... Calcium (Ca), iron (Fe), potassium (K), phosphorus (P), sulphur (S), and magnesium (Mg) were quantified in the different soil samples collected throughout the 2-year study to assess shifts in soil mineral composition that could be exploited for forensic applications (Melis et al., 2007;Aitkenhead-Peterson et al., 2012;Stokes et al., 2013;Macdonald et al., 2014;Szelecz et al., 2018). These were used subsequently to complement subsurface microbial community profiling for a more holistic toolkit. ...
... Likewise, phosphorous, magnesium and calcium are important elements for biological functions and soil nutrients. Phosphorous concentration was reported to change during decomposition (Benninger et al., 2008;Stokes et al., 2009Stokes et al., , 2013Szelecz et al., 2018) while calcium changes underneath bison carcasses were detectable up to 7 years after interment (Melis et al., 2007). ...
Introducing animal carbon-source to soil initiates biochemical and microbial processes that lead to its decomposition and recycling, which subsequently cause successional shifts in soil microbial community. To investigate the use of soil microbial community to inform criminal investigation, this study was designed to mimic clandestine graves. It compared the decomposition of stillborn piglets (Sus scrofa domesticus), as human analogues, to oak (Quercus robur) leaf litter and soil-only controls outdoors for 720 days. Environmental and edaphic parameters were monitored and showed soil microbial community alignment with temperature seasonality, which highlighted the importance of this abiotic factor. Denaturing gradient gel electrophoresis (DGGE) data were used to calculate Hill numbers and diversity indices of the bacterial 16S rRNA community did not distinguish mammalian- from plant-based decomposition consistently during the first or second year of the study. In contrast, the fungal 18S rRNA community allowed clear differentiation between different treatments (beta diversity) throughout the 720-day experiment and suggested the moment of the decomposing mammalian skin rupture. 16S rRNA-based NGS facilitated the identification of e.g., Pirellulaceae, Acidobacteria ii1-15_order and Candidatus xiphinematobacter as Year 2 bacterial markers of gravesoil at family, order and species taxonomic levels, respectively, and confirmed the similarity of the calculated Hill diversity metrics with those derived from DGGE profiling. Parallel soil elemental composition was measured by portable X-ray Fluorescence where calcium profiles for the piglet-associated soils were distinct from those without carrion. Also, soil calcium content and PMI correlated positively during the first year then negatively during the second. This study is one of the first to apply a multidisciplinary approach based on molecular and physicochemical analytical techniques to assess decomposition. It highlights the recognised potential of using soil microbial community in forensic investigations and provides a proof-of-concept for the application of a combined molecular and elemental approach to further understand the dynamics of decomposition. In addition, it sets the scene for further research in different conditions based on Hill numbers metrics instead of the classic ecological indices for soil necrobiome richness, diversity and evenness.
... Only a few studies have made direct comparisons: one study compared 10 non-human vertebrates ranging in mass from 6 g (deer mouse) to 13 kg (mule deer), revealing that mass loss rates were variable between species and not correlated to initial body mass (Parmenter and MacMahon, 2009). Another study comparing buried skeletal muscle tissue from four mammals (including humans) showed that while soil nutrient enrichment patterns associated with decomposition followed the same overall temporal patterns, there were differences in nitrogen flux; namely soil ammonium concentrations associated with porcine and bovine tissues were twice as high as human tissue (Stokes et al., 2013). To address the question of whether pigs can be used as proxies in forensic taphonomy research, a study was undertaken at the University of Tennessee Anthropology Research Facility (ARF). ...
... Decomposing rabbits also resulted in an increase in pH (Quaggiotto et al., 2019). It has also been noted that buried carcasses (both animal and human) generally cause an increase in pH (Hopkins et al., 2000;Wilson et al., 2007;Stokes et al., 2013;Keenan et al., 2018a). Our study has added to the growing body of observations that the response of soil pH to mammalian decomposition is not predictable and seems to depend on species and local environmental and edaphic conditions. ...
Vertebrate decomposition processes have important ecological implications and, in the case of human decomposition, forensic applications. Animals, especially domestic pigs ( Sus scrofa ), are frequently used as human analogs in forensic decomposition studies. However, recent research shows that humans and pigs do not necessarily decompose in the same manner, with differences in decomposition rates, patterns, and scavenging. The objective of our study was to extend these observations and determine if human and pig decomposition in terrestrial settings have different local impacts on soil biogeochemistry and microbial activity. In two seasonal trials (summer and winter), we simultaneously placed replicate human donors and pig carcasses on the soil surface and allowed them to decompose. In both human and pig decomposition-impacted soils, we observed elevated microbial respiration, protease activity, and ammonium, indicative of enhanced microbial ammonification and limited nitrification in soil during soft tissue decomposition. Soil respiration was comparable between summer and winter, indicating similar microbial activity; however, the magnitude of the pulse of decomposition products was greater in the summer. Using untargeted metabolomics and lipidomics approaches, we identified 38 metabolites and 54 lipids that were elevated in both human and pig decomposition-impacted soils. The most frequently detected metabolites were anthranilate, creatine, 5-hydroxyindoleacetic acid, taurine, xanthine, N -acetylglutamine, acetyllysine, and sedoheptulose 1/7-phosphate; the most frequently detected lipids were phosphatidylethanolamine and monogalactosyldiacylglycerol. Decomposition soils were also significantly enriched in metabolites belonging to amino acid metabolic pathways and the TCA cycle. Comparing humans and pigs, we noted several differences in soil biogeochemical responses. Soils under humans decreased in pH as decomposition progressed, while under pigs, soil pH increased. Additionally, under pigs we observed significantly higher ammonium and protease activities compared to humans. We identified several metabolites that were elevated in human decomposition soil compared to pig decomposition soil, including 2-oxo-4-methylthiobutanoate, sn-glycerol 3-phosphate, and tryptophan, suggesting different decomposition chemistries and timing between the two species. Together, our work shows that human and pig decomposition differ in terms of their impacts on soil biogeochemistry and microbial decomposer activities, adding to our understanding of decomposition ecology and informing the use of non-human models in forensic research.
... Surface soil (i.e. 0-15 cm) had a significantly higher concentration of extractable phosphorus, irrespective of land use pattern (Rao and Tarafdar 2002). ...
... Although a similar pattern of ammonia concentration was observed at 10 cm depth, the change was less apparent compared with 5 cm. Warm average temperature (32 AE 1.48C) and high pH (8) may have volatilised ammonia, and decreased its concentration in soil pore water (Stokes et al. 2013). As a result, less ammonia was transferred deeper into the soil column. ...
Changes of soil nutrients have been applied in legal investigations of the time of death or to locate a clandestine grave. However, the research on forensic soil chemistry under the unique tropical climate conditions in Malaysia is at its infancy stage, with only few available data to be used in forensic investigations. This study aims to study changes of soil nutrients (i.e., ammonia, phosphate, nitrate) as well as soil pH and electrical conductivity (EC), and its associated stages of decomposition of rat carcasses (n= 3) under controlled tropical climate conditions. The results showed fluctuations in soil pH between the control and carcass soil. Soil EC, concentrations for ammonia and phosphate increased during early decomposition stages, and declined thereafter. Nitrate concentration increased at the later stage of the decomposition process. We also found that the top layer of soil (i.e., 5 cm from soil surface) could render a significant pattern of soil nutrient dynamics compared to the soil at 10 cm depth from the surface, possibly due to: (1) slower rate of vertical transfer and (2) the washing off effect. We suggest that the soil EC value and changes of soil nutrient at the top 5 cm of the soil layer could potentially be useful in forensic investigation to: (1) determine the minimum postmortem interval (mPMI), (2) serve as an indicator for hidden graves and cadaver decomposition islands.
... British regulations do not allow the burial of human remains for research purposes. Therefore, taphonomic studies regularly employ domestic animal analogs (Pig; Sus scruff domesticus, Cow; Bus taurus, or sheep; Ovis aries), to study human decomposition (Stokes, Forbes, and Tibbett 2013). Pigs are considered to be biochemically and physiologically similar enough to humans to replace human test subjects for surgical techniques and medical experiments, as well as for forensic burials and decomposition research (Payne, King, and Beinhart 1968;Wilson et al. 2007). ...
... These fluctuations in conditions within the blanket bogs assisted in the formation of adipocere that, in turn, preserved the remains. Stokes, Forbes, and Tibbett (2013) conducted comparison studies to determine which animal analog (Pig; Sus scruff domesticus, Cow; Bus taurus, or sheep; Ovis aries) is the most precise predictor of human decomposition. They surmised that all models offered close approximations in decomposition dynamics. ...
Three pig forefeet were buried approximately 20 centimetres (cm) below the surface in the Dartmoor bogs for ten months. To understand the bog environmental chemistry and its potential diagenetic effects on buried porcine remains, we applied Portable X-ray Fluorescence Spectroscopy (pXRF) to the pig bone and burial soil. We also wanted to ascertain whether pXRF allows us to resolve whether the chemical changes that create bog bodies required extended immersion in the bog (millennia versus years or less). To assess the potential diagenetic effects of the bog, we analysed the elemental concentrations of soil samples at 10cm intervals, a soil sample at the burial depth, and a middle phalanx of the first pig using the Skyray Genius 5000 pXRF analyser. The pXRF analyser provided valuable information for understanding that chemical changes occurred within less than year, involving both incorporation and leaching of various elements in the bog.
... Numerous studies demonstrate that a decomposing cadaver affects soil and soil organisms drastically [5][6][7]. Especially cadaveric fluids change soil chemical properties [8]. Benninger et al. [9] observed a significant increase of soil pH, nitrogen, and phosphorous when exposing a pig cadaver to the soil. ...
... Numerous studies demonstrate that the early stage of decomposition of a cadaver affects soil and soil organisms drastically [5][6][7]. Especially cadaveric fluids change soil chemical properties in an often clearly visible way [8,35]. ...
... KEYWORDS: forensic science, forensic anthropology, bone mineral density, freezing, experimental studies, longitudinal analysis Many clinical and research studies in forensic science use animal cadavers (e.g., pigs and rats) as a proxy for human tissue (1)(2)(3). For example, many forensic anthropological studies of decomposition (4)(5)(6), experimental trauma, and biomechanical analyses (7-9) employ animal cadavers for human analog research purposes. ...
... Nonetheless, due to availability and insufficient supplies, animal cadavers, particularly carrion animals, may require periodic freezing in order to preserve test material prior to experimentation or deposition. This is a particularly salient point as most experimental studies within forensic anthropology are performed to assess the effects of modification in medicolegal contexts on fresh bone (1,2,5). Therefore, if freezing significantly alters remains prior to experimental testing, it could impact their validity when applied to cases of medicolegal significance. ...
It is common for researchers using animal or human remains for scientific study to freeze samples prior to use. However, effects of freezing on bone macro- or microstructure are relatively unknown. The research objective of this study was to determine whether freezing could potentially bias experimental results by analyzing changes in bone mineral density (BMD) with the freezing of remains over time. Eight fetal pigs were scanned to determine their initial BMD before freezing. Three piglets underwent a freeze-thaw cycle to assess the effects of the freezing process. Four piglets were frozen and scanned weekly for 20 weeks to assess freezing over time. The overall average between the fresh initial scan and final frozen scan was significantly different (p < 0.001). Per contra, the final thawed BMD scans did not differ from the initial fresh scan (p = 0.418). Thus, completely thawed remains are recommended for experimental studies.
... A number of controlled experiments have been conducted to examine the effect of freezing on both hard and soft tissue [72,73]. Field experiments, using pigs, have also been conducted in the United States of America [15,69,74] and in Canada [60] to examine the impact of freezing on decomposition. ...
... Field experiments, using pigs, have also been conducted in the United States of America [15,69,74] and in Canada [60] to examine the impact of freezing on decomposition. The lab studies found that freezing small disassociated soft tissue samples did not impact the re-thawed rate of decomposition or the soil chemistry compared to unfrozen samples [72]. The field studies found that there were differences in the rate and manner of decomposition between the previously frozen and fresh pigs [74]. ...
Little is known about the nature and trajectory of human decomposition in Canada. This study involved the examination of 96 retrospective police death investigation cases selected using the Canadian ViCLAS (Violent Crime Linkage Analysis System) and sudden death police databases. A classification system was designed and applied based on the latest visible stages of autolysis (stages 1–2), putrefaction (3–5) and skeletonisation (6–8) observed. The analysis of the progression of decomposition using time (Post Mortem Interval (PMI) in days) and temperature accumulated-degree-days (ADD) score found considerable variability during the putrefaction and skeletonisation phases, with poor predictability noted after stage 5 (post bloat). The visible progression of decomposition outdoors was characterized by a brown to black discolouration at stage 5 and remnant desiccated black tissue at stage 7. No bodies were totally skeletonised in under one year. Mummification of tissue was rare with earlier onset in winter as opposed to summer, considered likely due to lower seasonal humidity. It was found that neither ADD nor the PMI were significant dependent variables for the decomposition score with correlations of 53% for temperature and 41% for time. It took almost twice as much time and 1.5 times more temperature (ADD) for the set of cases exposed to cold and freezing temperatures (4 °C or less) to reach putrefaction compared to the warm group. The amount of precipitation and/or clothing had a negligible impact on the advancement of decomposition, whereas the lack of sun exposure (full shade) had a small positive effect. This study found that the poor predictability of onset and the duration of late stage decomposition, combined with our limited understanding of the full range of variables which influence the speed of decomposition, makes PMI estimations for exposed terrestrial cases in Canada unreliable, but also calls in question PMI estimations elsewhere.
... A similar situation arises for EC with variations between and within cemeteries ( Figure 6). Although it was not possible to evaluate EC over time due to the nature of this research, the data here reported agrees with a study conducted by Stokes et al. 46 which states that soil EC increases with decomposition. In the present study, higher values of EC were achieved at the graves of completely skeletonized bodies and not at the graves whose bodies still contained soft tissues. ...
Over the last decade, some Portuguese cemeteries have started to have issues with the lack of burial space, mainly due to the slow rate of cadaveric decomposition, hindering the reuse of soil graves as is common practice. To better understand the influence of soil on human taphonomy and help in cemetery management, the main goal of this research was to explore possible relationships between body decay and edaphic traits. A total of 217 soil samples were collected from graves of five public cemeteries and analysed for their soil organic matter content, moisture, pH, electrical conductivity, bulk density, texture, and colour. Five grave sampling areas were considered: the topsoil, above the coffin, and under the coffin in the head, pelvis and feet areas. Statistically significant differences have been found between the graves of skeletonized and incompletely skeletonized bodies for moisture above the coffin (p = 0.035) and for electrical conductivity in the topsoil (p = 0.014). Although the number of individuals (n = 56) studied might be considered low, this paper explores the possibility that soil itself might not be the main influencer on human taphonomy. A new perspective should be considered regarding the role played by intrinsic factors after death.
... In the UK, the Human Tissue Act (2004) governs the use of human remains, adding complexity to such research [8]. The use of animals analogues has become prominent due to ethical concerns, guided by the Animals (Scientific Procedures) Act (1986) and the Animal Welfare Act (2006) [9,10]. Studies have explored using animals like pigs and sheep as human analogues, assessing factors like skeletal muscle tissue mass loss [11]. ...
This work offers an overview of forensic taphonomy's recent advancements, focusing on the transition from traditional practices to modern interdisciplinary methods. It highlights ethical and legal aspects of using human cadavers in decomposition studies, referencing the UK's Human Tissue Act. The significance of taphonomic research facilities is underlined as key in forensic science advancement. Additionally, the work reviews methodologies like the Total Body Score and novel technologies such as 3D and thermal imaging for non-invasive, forensic applications. Future directions, including the need for more research facilities, international collaboration, and a global database for standardisation and machine learning integration, are proposed to enhance the field's efficacy and ethical compliance.
... Nevertheless, animal experiments must still follow ethical standards, guidelines and laws [134][135][136][137]. Because the carcass type can affect decomposition [138][139][140] and scavenging [96,141], the study of human analogues and the variability of species is a challenge for forensic research. Experiments on domestic pig carcasses were predominant in our review. ...
... As a result of collaboration with several medicolegal agencies across the USA, it has not escaped our notice that the approaches used over the course of ten carcass decomposition studies have potential to be used in the context of actual medicolegal death investigations. Although pig and human remains can present different postmortem processes and resource changes [7,19,87,88,[93][94][95][96][97][98], some fundamental decomposition processes can be sufficiently similar to inform investigative decision-making where postmortem changes obscure or mimic criminal activity [13,98,99]. This does not mean that the current data are appropriate for direct application to actual medicolegal death investigations. ...
Decomposition studies have been conducted in several regions of the world, but relatively few have investigated taphonomy in tropical environments. Even fewer have explored carcass decomposition during multiple tropical seasons, leaving the relationships between season and decomposition in tropical environments poorly understood. Ten decomposition studies using 30 carcasses were conducted in Honolulu, Hawaii, USA to start addressing this knowledge gap. These studies show that some postmortem processes were observed regardless of season. Carcass temperature and chemistry were spatiotemporally variable. Fly larval masses were consistently observed within 3 days (∼75 ADD) postmortem and carcasses lost 60%–90% of mass by 10 days (∼250 ADD) postmortem (Total Body Score ∼26). Season had a significant effect on decomposition, yet the warmest and most humid seasons did not always result in the most rapid and extensive decomposition. Seasonal variation appears to be less pronounced than at other tropical decomposition sites.
... However, with the emergence of human taphonomic research facilities, researchers have been able to directly compare the taphonomy of pigs and humans. Recent comparative studies have investigated the differences between pigs and humans with respect to adipose tissues [11], volatile organic compounds (VOCs) [12], insect succession [13][14][15][16], skeletal muscle tissue [17], soil biogeochemistry and microbiology [18] and total body scoring [19,20]. However, there remains an urgent need to continue these comparative studies in more fields, using different scientific methods in order to adequately assess whether pigs are suitable analogues for human decomposition work. ...
The determination of time since death is a major challenge to law enforcement when faced with the discovery of human remains. This is due to the fact that decomposition is a complex, dynamic process influenced by several abiotic and biotic factors. For decades, post-mortem decomposition studies have used pigs as human analogues due to ethical and legal restrictions surrounding the use of human cadavers for such research. However, few comparative studies have been conducted to assess the suitability of these analogues. Recent forensic studies have successfully demonstrated the use of post-mortem lipids in textiles as a method to obtain vital information about decomposition process. The current investigation involved two studies: Trial 1 (summer) and Trial 2 (winter). Each trial with n=1 human cadaver and n=2 pigs. Samples were collected over a timeline of 105 days post-placement and analysed using attenuated total reflectance (ATR) Fourier-transform infrared (FTIR) spectroscopy. The data was then statistically assessed using functional principal component analysis, semi-parametric regression modelling and analysis of variance. The results demonstrated a clear statistically significant interspecies difference between pigs and humans in both trials. The preliminary implications of this study suggest that pigs are not suitable analogues for humans in decomposition research and have broader implications that caution the direct translation of decomposition data obtained from pigs to real human casework, particularly with respect to time since death estimations.
... Comparative fecal metagenomics revealed that the pig fecal phyla are closer to that of cow rumen and chicken cecum (Lamendella et al., 2011). A comparison of the skeletal muscle tissue decomposition between human, pork, beef, and lamb showed that no single analog could precisely predict human decomposition in the soil, although they are all close approximations of the human decomposition dynamics (Stokes et al., 2013). Moreover, most studies on human thanatomicrobiome so far have been limited to the North American population. ...
Forensic medicine has, for a long time, been relying on biochemical, anthropologic, and histopathologic evidences in solving various investigations. However, depending on the method used, lengthy sample processing time, scanty sample, and less sensitivity and accuracy pervade these procedures. Accordingly, newer arenas such as the thanatomicrobiome have come forward to aid in its quandaries; furthermore, the parallel advances in genomic and proteomic techniques have complemented and are still emerging to be used in forensic experiments and investigations. Postmortem interval (PMI) is one of the most important aspects of medico-legal investigations. The current trend in PMI estimation is toward genomic analyses of autopsy samples. Similarly, determination of cause of death, although a domain of medical sciences, is being targeted as the next level of forensic casework. With the current trend in laboratory sciences moving to the discovery of newer disease-specific markers for diagnostic and prognostic purposes, the same is being explored for the determination of the cause of death by using techniques such as Real-Time PCR, DNA micro-array, to Next-Gen Sequencing. Establishing an individual’s biological profile has been done using medicolegal methods and anthropology as well as bar-bodies/Davidson bodies (gender determination); and in cases where the determination of age/gender is a challenge using morphological characteristics; the recent advances in the field of genomics and proteomics have played a significant role, e.g., use of mitochondrial DNA in age estimation and in maternity disputes. The major hurdle forensic medical research faces is the fact that most of the studies are conducted in animal models, which are often difficult to mimic in human and real-time scenarios. Additionally, the high accuracy required in criminal investigations to be used in a court of law as evidence has prevented these results to come out of the labs and be used to the optimum. The current review aims at giving a comprehensive and critical account of the various molecular biology techniques including “thanatogenomics,” currently being utilized in the veritable fields of forensic medicine.
... Numerous types of animal models have been employed, such as rabbits [6], guinea pigs [7], dogs [8], monkeys [9], impalas [10], rats [11] and pigs [12]. However, there has so far been very little research attempting to verify if other animals are reliable proxies for humans in forensic science research [13][14][15][16]. ...
Non-human vertebrate animals, primarily domestic pigs, have been widely used in forensic science research as analogues for humans due to ethical and logistical constraints. Yet the suitability of pigs to mimic human decomposition and entomological patterns remains largely untested, and explicit comparative research in this area is lacking. We compared the decomposition rates and insect communities found at pig and human remains during summer and winter at the Australian Facility for Taphonomic Experimental Research (AFTER). Pigs decomposed faster than humans, with pigs entering active decay earlier in both summer and winter, and humans undergoing desiccation rather than skeletonisation. There was also a delay in the colonisation of humans by both flies and beetles. Species richness of these necrophagous taxa was between two and five times higher during the first two weeks of decomposition on pigs compared to humans during both summer and winter. Insect species composition was also significantly different between pigs and humans in each season. We interpret our findings to mean that the difference between humans and pigs, such as their mass, diet, medical history, or their microbiomes, might be causing different decomposition processes and altered timing or production of chemical cues for insect colonisation. Although preliminary, our results suggest that pigs might not be accurate substitutes for humans in particular fields of taphonomy and forensic entomology. Our findings also have broader implications for the reliability of forensic studies using pigs as models for humans, and highlight the need to recognise intrinsic differences between animal models and humans.
... In the absence of a HTF, many researchers continue to use human analogues such as dogs, cats, rodents, monkeys, deer and most commonly domesticated pigs (Sus scrofa) as decomposition research test subjects [7,8]. These studies can benefit from using animal remains, since it is argued that they provide larger sample sizes and greater homogeneity due to similarities in genetics and rearing conditions between individuals [9,10]. ...
REST[ES] is the first Canadian human taphonomic facility (HTF) dedicated to research and training relating to human decomposition in a northern temperate climate. The following paper outlines the measures taken to successfully establish, open and operate this novel Canadian HTF with particular focus on: project team and partnerships, facility location, approvals and permits, infrastructure and social acceptability. It is intended that our experience of establishing REST[ES] may serve as an example to help others with the establishment of future HTFs, thus contributing to the expansion in the global accessibility to human decomposition research and training.
... Muscle tissue, in addition to fat, is another tissue of taphonomic importance in humans. Lab studies on small amounts (1.5 g) of skeletal muscle tissue buried in soil were assessed for decomposition differences between humans, cow, lamb and pigs [19]. No single animal analogue's muscle was a reliable surrogate for human muscle, however, lamb, not pig, muscle produced most similar results to human. ...
Forensic taphonomy as a discipline requires standardization to satisfy Daubert criteria for scientific data to be admissible in court. In response, there has been a shift towards quantification of methodology and estimating the post-mortem interval. Despite these advances, there are still biases and limitations within the discipline not explicitly addressed in the early stages of experimental design nor in final published works. In this article, unresolved debates with respect to the conductance and reporting of forensic taphonomic research are reviewed, beginning with the nature of experimental cadavers, human or animal analogues and their body size, and second, the forensic realism of experimental setups, specifically with respect to caging, clothing and number of carcases. Pigs, albeit imperfect, are a good model to gain a general idea of the trends that may be seen in humans in subsequent validation studies in facilities where human donors are available. To date, there is no consensus among taphonomists on the extent of the effect that body mass has on decomposition progression. More research is required with both human cadavers and non-human analogues that builds on our current knowledge of forensic taphonomy to answer these nagging questions. This will enable the discipline to make the reliable assumption that pigs and donor decomposition data can be applied to homicide cases. A suite of experimental design aspects is suggested to ensure systematic and standardized data collection across different biogeoclimatic circumstances to identify and quantify the effects of potential confounding variables. Such studies in multiple, varied biogeographic circumstances with standardized protocols, equipment and carrion will facilitate independent global validation of patterns. These factors are reviewed to show the need for adjustments in experimental design to ensure relevance and applicability of data within locally realistic forensic situations. The initiation of a global decomposition data network for forensic taphonomists is recommended.
• Key points
• Pigs are a valuable, albeit imperfect, proxy for human decomposition studies.
• There are few or conflicting data on effects of carcase size, carrion ecology, exclusion cages and scavengers.
• We recommend single, clothed, uncaged carcases for baseline research to reflect regionally specific forensic casework.
... This project contains certain limitations regarding the use of domesticated pigs as human proxies. Sus scrofa domesticus may share some anatomical similarities with humans, but differences remain in replacing this species with a Homo sapiens subject in forensic contexts (22)(23)(24). This paper strongly assumes that DNA degradation and subsequent leaching in Sus scrofa domesticus behave similarly to Homo sapiens. ...
Preservation variance of soil DNA is neglected in the literature, and exceptional cases exaggerate amplification capabilities. This study sought to amplify a short mitochondrial fragment (212 bp) specific to Sus scrofa domesticus from the soil surrounding decomposing pig remains from an open‐air locale. Samples collected above the body at incremental distances after 145 days of initial placement yielded pig DNA. A secondary sampling was collected in 2017, approximately 768 days after burial. Inhibition tests corroborated that pig DNA was no longer present in the soil resulting in a loss of original DNA between 145 and 768 days. The results provide evidence that genetic material leaches out radially from the source and DNA fragments longer than 200 bp do not persist in soil for a relatively short timeframe in western Montana. The conclusions support the collection of soil in crime scene investigation procedures within the first few months of decomposition.
... Although specific areas of an individual's microbiome are unique, there is also overlap of bacterial composition or at least function (Fierer et al. 2008(Fierer et al. , 2010Hyde et al. 2013). A study comparing the decomposition of skeletal muscle from several vertebrate species, including humans, demonstrated similar decomposition dynamics for microbial activity and mass of tissue loss (Stokes et al. 2013). Also, repetitive use of the same deposition study site with different individuals resulted in similar soil nutrient changes and an increased rate of decomposition likely due to enhancement of soil microbes able to utilize carrion (Carter and Tibbett 2008;Damann et al. 2012). ...
Ecological studies on the decomposition of nonliving organic matter have historically focused on plant systems (Swift et al. 1979; Moore et al. 2004; Hättenschwiler et al. 2005; Gessner et al. 2010). A fundamental component of any type of detrital decomposition is the microbial community, an assemblage of organisms representing all three domains of life (Woese et al. 1990), including prokaryotes of the bacteria and archaea domains and several representative taxonomic groups of the eukarya domain (e.g., fungi, protozoans, heterotrophic algae, microarthropods, and some worms). Research describing and quantifying the microbial importance to decomposition, nutrient cycling, and energy elaboration has been predominately from studies on photosynthetically derived decaying organic matter (e.g., leaf litter) and has largely neglected the functional contribution of heterotrophically derived decomposition (e.g., carrion) to ecosystem processes (Chapter 1). Because of this difference in historical study between photosynthetically derived and heterotrophically derived biomass decomposition, this chapter will briefly review the microbial communities important to plant litter decomposition (detritus) and then concentrate on providing a conceptual foundation for those neglected communities, processes, and functions associated with carrion decomposition.
... Coprostanol may be converted to epicoprostanol during sewage treatment (McCalley et al., 1981). Furthermore, the formation of epi-5b-stigmastanol can be observed during compost formation and in old sewage sludge (McCalley et al., 1981;Stokes et al., 2013;Prost et al., 2017). It is likely that the formation of epi-coprostanol and epi-5b-stigmastanol has been enhanced by anaerobic processes during the 18 days before the decaying body was removed from the soil surface (McCalley et al., 1981;Bull et al., 2002). ...
The decomposition of animal and human cadavers can lead to comprehensive chemical and biochemical changes in soil, which can provide helpful information for the analysis of archaeological and crime scenes. The current study focused specifically on the concentration and distribution patterns of steroids in soil with the aim of assessing their suitability for demonstrating the presence of human decomposition products. Soil samples were collected from a forensic site where a human corpse had been lying on the soil surface for 18 days. Total organic carbon (TOC) and steroid concentrations were analysed in soil samples taken from beneath the body at the time the corpse was removed and also one year later. High concentrations of TOC and steroids were detected close to the soil surface at the time the body was removed, and the concentration of cadaver-derived cholesterol was considerably higher than that of the plant-derived sitosterol. The soil beneath the cadaver contained higher concentrations of faeces-derived 5β-stanol coprostanol than the control soil. Different concentrations and distribution patterns of steroid compounds in the soil upon removal of the corpse and one year later indicate that significant transformation, degradation and translocation processes had taken place during this period of time. The depth distribution of steroids beneath a decomposing body along with changes in the human steroidal fingerprints in soil over time were found to provide information that could help resolve forensic and archaeological issues. The combined analysis of tissue steroids (cholesterol), the reduction product of cholesterol in soil (5α-cholestanol) as well as faecal steroids (coprostanol, 5β-stigmastanol and their conversion products epicoprostanol and epi-5β-stigmastanol) represent excellent additions to the forensic toolbox for determining whether a soil of interest has ever been affected by a human cadaver or not.
... Entretanto, a utilização deste íon na previsão do intervalo pós-morte ainda deve ser avaliada com mais cautela, visto que na literatura ainda não há registros que comparem o comportamento dos microelementos durante a decomposição cadavérica de humanos e de mamíferos considerados análogos. 1,9,[41][42][43][44] Com relação ao cobre e ao manganês não foram observadas modificações em suas variações durante o experimento, o que pode ser atribuído ao fato de serem micronutrientes, encontrados em pouca quantidade no organismo de mamíferos. Por serem disponibilizados em baixas concentrações para o solo estes não seriam capazes de mostrar alterações mensuráveis durante a decomposição. ...
The estimation of the Post-Mortem Interval (PMI) is a primordial parameter in the investigation of crimes against life. In tropical climate areas, the cadaveric decomposition occurs in an accelerated form, preventing the PMI estimation by usual methods. Understanding how different circumstances affect the cadaveric composition is very important to develop methods that enable the PMI estimation in several climatic conditions. One of the alternatives, however not much explored in Brazil, refers to the use of soil chemistry for the determination of longstanding PMIs. In this research, variations in soil chemical properties were monitored during swine carcasses cadaverous decomposition in a tropical forest area in order to recognize patterns and evaluate the applicability of these by the criminal expertise. Among the evaluated characteristics are the levels of pH, inorganic nitrogen (ammonia and nitrate), total nitrogen, carbon nitrogen proportion (C: N), exchangeable aluminum, available phosphorus and macro and micronutrients. The results showed distinct variations according to the decomposition phases observed and also to the way the carcasses were deposited in the study environment (above or below the soil), evidencing the possibility of using these variations in the development of models for the prediction of postmortem intervals lasting up to 67 days. © 2018 Secretaria Regional do Rio de Janeiro da Sociedade Brasileira de Quimica. All rights reserved.
... La conveniencia de un modelo animal (diferente al cuerpo humano) en investigaciones forenses está relacionada con el grado de similitud entre los resultados obtenidos en el modelo comparado con la condición humana, ya que finalmente, el objetivo del uso del modelo animal es transferir el producto a la práctica humana. De esta manera, puede ser posible adaptar los estudios de descomposición utilizando diferentes modelos animales (diferentes al humano) para situaciones específicas, y así obtener mayor precisión en la representación de la descomposición humana (Stokes, Forbes, & Tibbett, 2013). ...
... The overall patterns of nutrient luxes and chemical changes in non-human tissues and the underlying soil followed that of human tissues. Though no single analogue was a precise predictor of human decomposition in soil, all models offered close approximations in decomposition dynamics [13]. ...
... Pigs were considered suitable human decomposition analogues due to the similarity of their internal anatomy and gut biota to humans. They are also more readily available and often do not require ethics approval (i.e. for adults not bred for research purposes) 11 . However, the recently established Australian Facility for Taphonomic Experimental Research (AFTER) is a licensed facility that meets the ethical and legal requirements necessary for research involving human cadavers, but such research can only be conducted in the local environment of Sydney. ...
Cadaver-detection dogs are trained to locate victim remains; however, their training is challenging owing to limited access to human remains. Animal analogues, such as pigs, are typically used as alternative training aids. This project aimed to compare the visual decomposition and volatile organic compound (VOC) profile of human and pig remains in an Australian environment, to determine the suitability of pig remains as human odour analogues for cadaver-detection dog training. Four human cadavers and four pig carcasses were placed in an outdoor environment at the Australian Facility for Taphonomic Experimental Research (AFTER) across two seasons. Decomposition was monitored progressively in summer and winter. VOCs were collected onto sorbent tubes and analysed using comprehensive two-dimensional gas chromatography – time-of-flight mass spectrometry. Visual observations highlighted the differences in decomposition rates, with pig remains progressing through all stages of decomposition, and human remains undergoing differential decomposition and mummification. Chemical and statistical analysis highlighted variations in the composition and abundance of VOCs over time between the odour profiles. This study concluded that the visual decomposition and VOC profile of pig and human remains was dissimilar. However, in cooler conditions the results from each species became more comparable, especially during the early stages of decomposition.
... The overall patterns of nutrient luxes and chemical changes in non-human tissues and the underlying soil followed that of human tissues. Though no single analogue was a precise predictor of human decomposition in soil, all models offered close approximations in decomposition dynamics [13]. ...
... Future research will inevitably have to consider this complex factor. Additionally, Stokes et al. [45] investigated how far animal models of muscle tissue loss are able to accurately model human decomposition dynamics, but with pork, beef and lamb, they found no single analogue to be a precise approximation modelling human decomposition dynamics. However, Pittner et al. [46,47] have recently revealed promising results by looking at the protein changes using Western Blotting and casein zymography. ...
Aims:
Bacteria are considered one of the major driving forces of the mammalian decomposition process and have only recently been recognised as forensic tools. At this point, little is known about their potential use as 'post-mortem clocks'. This study aimed to establish the proof of concept for using bacterial identification as post-mortem interval (PMI) indicators, using a multi-omics approach.
Methods and results:
Pieces of pork were placed in the University's outdoor facility and surface swabs were taken at regular intervals up to 60 days. Terminal restriction fragment length polymorphism (T-RFLP) of the 16S rDNA was used to identify bacterial taxa. It succeeded in detecting two out of three key contributors involved in decomposition and represents the first study to reveal Vibrionaceae as abundant on decomposing pork. However, a high fraction of present bacterial taxa could not be identified by T-RFLP. Proteomic analyses were also performed at selected time points, and they partially succeeded in the identification of precise strains, subspecies and species of bacteria that colonized the body after different PMIs.
Conclusion:
T-RFLP is incapable of reliably and fully identifying bacterial taxa, whereas proteomics could help in the identification of specific strains of bacteria. Nevertheless, microbial identification by next generation sequencing might be used as PMI clock in future investigations and in conjunction with information provided by forensic entomologists.
Significance and impact of the study:
To the best of our knowledge, this work represents the first attempt to find a cheaper and easily accessible, culture-independent alternative to high-throughput techniques to establish a 'microbial clock', in combination with proteomic strategies to address this issue.
... The cages also allowed moving the cadavers for sampling. Pigs are commonly used in comparable forensic studies due to the similarities with humans, comparable thoracic cage size and almost naked skin [47]. Each treatment was run in triplicate. ...
Impact of cadaver on forest soil Euglyphid assessed by metabarcoding
Researchers have observed that rainfall may re-initiate decomposition in desiccated tissue; however, no conclusive research-based evidence exists on the specific effects of rehydration on decomposition. Therefore, this study aimed to assess the effects of artificial rehydration on the progression of decomposition following the advanced stage of decomposition. Twelve adult pig cadavers (8 experimental; 4 controls) were placed in the central Highveld of South Africa during cooler (April-July 2021) and warmer (August-November 2021) months. Decomposition was scored approximately biweekly to obtain the total body score, and accumulated degree days (ADD) were calculated for each pig. All pig cadavers were covered by chicken wire cages with transparent tarps to control for natural rehydration and scavenging. Once the experimental pig cadavers reached a three-visit stasis in the advanced phase of decomposition, they were artificially rehydrated, and changes in the progression of decomposition between the control and experimental groups were plotted (ADD against TBS) for observation. The rehydrated experimental pig cadavers showed re-initiation of decay and insect re-colonization, while the control cadavers mainly remained in a state of stasis with insect activity ceased altogether. Greater cadaver decomposition islands and a color change post-rehydration were also noted in some experimental cadavers. This supports the need for future research on the impact of rehydration, including associated soil moisture on decomposition rates, progression, and invertebrate colonization, which will enhance our understanding of the effects these environmental factors have on the accuracy of post-mortem interval estimation.
Purpose
This study aimed to investigate whether there is a relationship between the body size of a cadaver and the rate of decomposition, specifically focusing on juvenile remains. The research sought to address the lack of comprehensive studies on how juvenile-sized cadavers decompose compared to adults, which has direct relevance to forensic science and crime statistics involving juvenile victims.
Methods
The study utilized pig cadavers representing two size groups, with regular monitoring of total body score (TBS) and percentage mass change (PMC) over an 18-week period. To ensure the reliability of the TBS system, three independent observers assessed the cadavers.
Results
Findings revealed that larger cadavers, ranging (12.3–16.1 kilograms), decomposed more rapidly during the initial stages of decomposition. However, smaller cadavers, weighing between (6.6–7.1 kilograms), consistently exhibited accelerated decomposition rates compared to larger cadavers from weeks four to twelve when assessed using TBS. Importantly, the inter-rater evaluation of the TBS system demonstrated a high inter-rater reliability.
Conclusion
This study addresses a critical gap in forensic science research by shedding light on the decomposition patterns of juvenile-sized remains. The findings have significant implications for crime statistics, particularly in cases involving juvenile victims, where a comprehensive understanding of decomposition rates can aid investigations. Given the high rates of unsolved cases involving juvenile victims, this research underscores the need for further studies in this specific area, particularly within a UK context. Such research can potentially lead to more effective crime-solving strategies and contribute to improving the handling of juvenile remains in forensic investigations.
Forensic anthropologists have expertize in the analysis of the human skeleton and are routinely involved in cases involving deceased persons but may also be consulted in cases concerning living persons. Forensic anthropologists are typically requested to examine complete and /or fragmentary human remains in different states of preservation including, but not limited to, fresh, decomposed, traumatized, and/or burnt. This article describes the range of possible analyzes the forensic anthropologist may undertake. The type of contexts where a forensic anthropologist may work are discussed; highlighting that the contribution made by the forensic anthropologist will differ depending not only on preservation, but also on the type of case, and therefore the associated questions being asked. Developments in research and teaching in forensic anthropology are then discussed and professional issues posed by such developments are considered.
The accepted paradigm of foreign animal disease preparedness in Canada, the emergency for which to prepare, starts with identification of the exotic viral agent in a Canadian farm animal population. This narrative focuses on the containment of the infectious agent, within diseased animals, on infected premises. Framing the emergency as a disease incursion limits rational imagination to only one version of one potential animal emergency. This framing of the problem directs the carcass disposal solutions to consider only methods to dispose of viral infected material. However, in all documented responses to catastrophic swine diseases in the past three decades, the number of uninfected animals caught up in movement control zones and killed greatly exceeds the number of infected animals killed. The temporary closures of slaughterhouses in spring 2020 due to COVID-19 transmission resulted in thousands of healthy market hogs surplus to market; an unanticipated emergency of healthy pigs. This paper proposes an alternate carcass disposal option for material from uninfected farms. "Excarnation by exposure" is a natural process of debulking and dehydrating carcasses by blow fly larvae, mitigating financial costs of final disposal. Excarnation by exposure is a reasonable and possibly necessary additional option for the management of uninfected carcasses in a catastrophic emergency response in commercial pigs.
Microbiological studies show that there is a possibility of PMI estimation in reference to presence of typical bacteria and fungi on cadaver or in soil beneath. Microbiome after death (thanatomicrobiome) changes and depends on time since death, temperature, seasons and environment-if human remains are covered, buried, placed in ice or left on the surface. To enlarge current knowledge, some of studies are conducted on animal models with further comparison thanatomicrobiome of different animals-pig, rats-to human cadaver thanatomicrobiome. This study collects different branches of thanatomicrobiome studies as a review to summarize current knowledge.
1. Introduction. 2. Living host microbiome and mycobiome. 3. Diseases-related differences. 4. Thanatomicrobiome – human cadavers studies. 5. Fungi presence – thanatomycobiome. 6. Thanatomicrobiome of frozen cadavers. 7. Soil microbial communities changes. 8. Seasons related microbial changes. 9. Thanatomicrobiome and entomology correlation. 10. Conclusions
Taphonomy is the study of decaying organisms over time and their process of fossilization. Taphonomy, originally a branch of palaeontology and anthropology, was developed to understand the ecology of a decomposition site, how site ecology changes upon the introduction of plant or animal remains and, in turn, how site ecology affects the decomposition of these materials. In recent years, these goals were incorporated by forensic science to understand the decomposition of human cadavers, to provide a basis on which to estimate postmortem and/or postburial interval, to assist in the determination of cause and circumstances of death, and to aid in the location of clandestine graves. These goals are achieved through the study of the factors that influence cadaver decomposition (e.g. temperature, moisture, insect activity). These studies have also provided insight into the belowground ecology of cadaver breakdown and allowed to develop useful protocols for mass disaster managements in humanitarian medicine. From the results obtained, new scientific disciplines have arisen, gathered under the word “taphonomics” such as the study of microorganisms living below/on a cadaver (thanatogeomicrobiology), and join the more classical forensic sciences such as anthropology, botany or entomology. Taking into account the specificities of the study object (human cadaver), primordial requirements are needed in terms of security (physical and environmental) as well as ethical and legal concerns which are studied in the Swiss context. The present review aims to present in a first part the concept of human forensic taphonomy facilities (HFTF, also colloquially named “body farm”) leading to an enrichment of forensic sciences with new “taphonomics”. The second part is focused on the mandatory points that must be addressed for a HFTF approach, especially because it requires a specific place to undertake this research which must be performed in conformity with a country’s human ethics and laws.
Thermal imaging is commonly used by forensic search investigators to locate missing persons, but there is little research on it’s actual effectiveness to detect individuals after death. This paper aims to answer fundamental questions on how long thermal imaging is effective to detect a body lying on the surface and when is the optimal time in a day to survey. A simulated murder victim, using a freshly dispatched pig (Sus scrofa) carcass, was left on the soil surface of a test site and imaged three times a day over a 61-day study period. Images were quantitatively analysed to determine what the relative thermal response the cadaver had with respect to background values, with results corrected for daily temperature (ADD) and decomposition rate (TBS scores). Results evidenced the surface cadaver could be detectable throughout the 61 day study period, but there were differences depending on when the survey was conducted during the day. Morning surveys were found to be optimal up to 10 days PMI (0-90 ADD), evening/dusk surveys optimal from 10 to 40 days PMI (90-400 ADD), midday surveys optimal from 40 to 50 days PMI (400-530 ADD) and then evening surveys to the end of the 61-day (400-680 ADD) study period. Implications suggest that thermal imaging is recommended to detect missing persons even after death and surveys should be undertaken at specific time periods during the day to improve search detection success if PMI can be estimated.
Human Taphonomy Facilities are outdoor laboratories where forensic scientists investigate and monitor the decomposition of donated human cadavers in a variety of conditions. The use of human cadavers for this purpose is potentially controversial, as opinions differ about the value of the research conducted at such facilities and the extent to which the dignity of the deceased is preserved. As a result of the use of human cadavers for forensic research, there are ethical issues to consider if contemplating the creation of such a facility. Currently, there is no such facility in the UK, and the legal and ethical landscape in the UK regarding the use of human tissue is unique. Therefore, this chapter outlines the ethical considerations surrounding the creation of a Human Taphonomy Facility (HTF) in the United Kingdom. It starts with an overview of why controlled experiments are necessary for forensic investigations, and their potential importance for search and dating discovered remains. The chapter then acknowledges and discusses the usefulness of animal proxies for this research, with benefits of replicants, known age/diet, and availability. The rest of the paper then defines a HTF, explaining the need for controlled research and the importance of using human remains for controlled experiments. Finally, a discussion on why donation of human organs is routine and whole cadavers is not, the potential ethical considerations for body donation, the mechanics of how to run a HTF, and ultimately the considerations of public opinion.
Geophysical survey has become a major tool in the search for clandestine graves associated with missing person cases. However, relatively little research has been done to evaluate the efficacy of different instruments. Ground-penetrating Radar (GPR), magnetometry, resistivity, conductivity, and susceptibility survey data were collected over the first six months of interment at approximately 30-day intervals for two research plots: an open grassy area and a wooded area. Each area contained five pig burials representing toddler-size (less than 50 pounds) remains and two areas of disturbance or false burials to serve as control graves. The resultant imagery was evaluated in terms of relative utility in burial detection. In general, geophysical survey method results were not very effective in the detection of toddler-sized burials. Under the conditions that this research was conducted, the GPR would have had the maximum potential to provide the best survey results, but this was not the case. The GPR results were only marginally better than the other methods after processing with additional filters. The other methods utilized in this research would be of no benefit in delineating toddler-sized clandestine burials under the conditions that this research was conducted. This is most likely due to the small target size, soil type, and the soil moisture. iii DEDICATION This thesis is dedicated to my children, Ronnie and McKenzie Leanne. They have become my inspiration and provide hope... iv ACKNOWLEDGMENTS
This represents one of several sections of "A Bibliography Related to Crime Scene Interpretation with Emphases in Geotaphonomic and Forensic Archaeological Field Techniques, Nineteenth Edition" (The complete bibliography is also included at ResearchGate.net.). This is the most recent edition of a bibliography containing resources for multiple areas of crime scene, and particularly outdoor crime scene, investigations. It replaces the prior edition and contains approximately 10,000 additional citations. As an ongoing project, additional references, as encountered, will be added to future editions.
Taphonomy has been defined as the study of the processes by which animal and plant remains become fossilized. The discipline arose from the work of paleontologists to explain the contexts and conditions of fossilized remains. Taphonomy, with its roots in the Greek “taphos” for tomb or burial, and “nomos”-laws, was adapted by physical anthropologists to explain, and sometimes predict, the condition and contexts of more recent and often forensically significant finds. In this respect, and especially as it applies to forensic situations, taphonomy has come generally to refer to the science of examining transitions of remains from the biosphere to the lithosphere as impacted by weather, animals, plants, biochemical reactions, and cultural factors. Marin-Arroyo,et al. (2012), Dirkmaat (2013), and Borrini and Tomba (2014), serve as some of the most recent works discussing the various forms those transitions might entail. They represent three of many sources, offered below, which demonstrate the multitude of areas currently being researched to explain reasons for, and the results of, particular transitional events. Taphonomy includes various agents of bone modification, but is not limited to that alone. Soft tissue transitions occur as do those to hair, nails, wound and other defects.
The general Taphonomy section has been broken into individual sections for topics of "Decomposition and Time Since Death", "Disease, Illness, and Physical Abnormalities", "Thermal Alterations and Influences", "Scavenging, Animal Attacks, Faunalturbation, and Bitemark Evidence", "Trauma" and "General or Miscellaneous Topics". References in each of these sections may be related to other sections of the bibliography. For example, the topic of wounds comprise part of the taphonomic record on a body or it's remains. As a result, one of the largest subsections under Taphonomy is devoted to sharp, blunt, ballistic and other traumas. Researchers interested in this subarea of taphonomy should also search Firearms and Toolmark Evidence in as much as resources on terminal ballistics or wound ballistics may be included in that section of this bibliography. Another example may include the relationship between bite marks and criminal behavior. As taphonomists, physical anthropologists are interested in both skeletal and soft tissue injuries, as well as changes to those matrices and their injuries over time. One form of taphonomic change which takes place over time is decomposition. Whether it be the formation of adipocere, diagenesis of bone, or cremation as a form of further concealment, the condition of tissues can reflect changes in environment and/or the length of time since disposal. In almost every environment where remains are disposed or concealed, animals, large and small, feed or otherwise scavenge decomposing tissue. Such modifications are addressed in a subsection on scavenging. Modifications of interest to anthropologists and pathologists can also be caused by feeding insects, to which they are refered to the section on Entomology. Another large grouping of references in this category consist of those about diseases and illness. The antemortem health of victims as reflected in their remains is as important for the forensic investigator as reflections of peri-and postmortem circumstances. Certain conditions such as bone diseases, broken bones, or the use of prosthetics, can aid investigators in identifying victims or reconstructing a victim's ability to perform certain actions associated with their deaths or disappearance.
Because of taphonomy’s roots in paleontology, many of the resources in this section deal exclusively with paleontological theory and method. Prehistoric archaeological examples of taphonomy also constitute several citations. It is important for researchers to understand the bases for theories and methodologies which have come to be applied in forensic settings. Just as traditional physical anthropology and archaeology drew upon the earlier works of paleontologists, much current work in forensic taphonomy relies upon discoveries made during the exhumation of historic and prehistoric burials. The reader is referred back to the section on "Excavation and Recovery Strategies" for additional archaeological site reports which may contain taphonomy related information. Likewise, “General Crime Scene and Death Scene Investigation” may contain research regarding wound or trauma analysis and pathology - topics which are inherently taphonomic. From wound, (or terminal), ballistics to transitional, or (external), ballistics and ultimately to initial, (or internal), ballistics, the taphonomic record of gunshot wounds is linked to the examination of firearms and ammunition. Readers interested in resources related to gunshot wounds should also refer to the category of Firearms and Toolmark Evidence. Additionally categories such as Mass Fatality and Human Rights Investigations should be reviewed for references which contain details of site environments, (ie: mass graves, building collapses), or manners of death , (ie: torture, post-blast, or crash conditions), which impact the taphonomy of remains.
Human Taphonomy Facilities (HTFs) are outdoor laboratories where scientific research is carried out on donated human cadavers in order to understand how human decomposition progresses in a variety of conditions. There are currently eight such facilities in the USA, one in Australia and one on mainland Europe. Forensic scientists in the UK have started to ask the question ‘Does the UK need a Human Taphonomy Facility?’. A review of the literature produced by the existing HTFs, as well as published opinion and commentaries about these facilities and the feasibility of one in the UK has been undertaken. The existing arguments for and against the establishment of a Human Taphonomy Facility in the UK have been examined. Given recent media interest in the possibility of the establishment of a Human Taphonomy Facility in the UK, and the surrounding controversy, it is important to evaluate the potential benefit or harm of the creation of such a facility to Society and the scientific community.
Decomposing vertebrate cadavers release large, localized inputs of nutrients. These temporally limited resource patches affect nutrient cycling and soil organisms. The impact of decomposing cadavers on soil chemistry is relevant to soil biology, as a natural disturbance, and forensic science, to estimate the postmortem interval. However, cadaver impacts on soils are rarely studied, making it difficult to identify common patterns. We investigated the effects of decomposing pig cadavers (Sus scrofa domesticus) on soil chemistry (pH, ammonium, nitrate, nitrogen, phosphorous, potassium and carbon) over a one-year period in a spruce-dominant forest. Four treatments were applied, each with five replicates: two treatments including pig cadavers (placed on the ground and hung one metre above ground) and two controls (bare soil and bags filled with soil placed on the ground i.e. "fake pig" treatment). In the first two months (15-59 days after the start of the experiment), cadavers caused significant increases of ammonium, nitrogen, phosphorous and potassium (p<0.05) whereas nitrate significantly increased towards the end of the study (263-367 days; p<0.05). Soil pH increased significantly at first and then decreased significantly at the end of the experiment. After one year, some markers returned to basal levels (i.e. not significantly different from control plots), whereas others were still significantly different. Based on these response patterns and in comparison with previous studies, we define three categories of chemical markers that may have the potential to date the time since death: early peak markers (EPM), late peak markers (LPM) and late decrease markers (LDM). The marker categories will enhance our understanding of soil processes and can be highly useful when changes in soil chemistry are related to changes in the composition of soil organism communities. For actual casework further studies and more data are necessary to refine the marker categories along a more precise timeline and to develop a method that can be used in court.
Pigs are a common human analogue in taphonomic study, yet data comparing the trajectory of decomposition between the two groups are lacking. This study compared decomposition rate and gross tissue change in 17 pigs and 22 human remains placed in the Forensic Investigation Research Station in western Colorado between 2012 and 2015. Accumulated degree days (ADD) were used to assess the number of thermal units required to reach a given total body score (TBS) (1) which was used as the measure of decomposition. A comparison of slopes in linear mixed effects model indicated that decomposition rates significantly differed between human donors and pig remains χ2(1) = 5.662, p = 0.017. Neither the pig nor the human trajectory compared well to the TBS model. Thus, (i) pigs are not an adequate proxy for human decomposition studies, and (ii) in the semiarid environment of western Colorado, there is a need to develop a regional decomposition model.
Hebeloma vinosophyllum (Basidiomycota, Agaricales), a member of the ammonia fungi, occurred on the ground in the close vicinity of the decomposed
carcass of a jungle crow,Corvus macrorhynchos, in a forest dominated byQuercus spp. in Urawa, Saitama Pref., central Japan. This is the first report of an ammonia fungus occurring at the site of a decomposed
wild bird carcass.
A new tripartite relationship among animals, fungi, and plants, based on formation of ectomycorrhiza and on removal of animal wastes, is described. In forest habitats where animal wastes such as urine or faeces or dead bodies, mainly of mammals, have been deposited, a particular group of fungi form reproductive structures successionally after the apparent decomposition of the wastes. This natural event can be simulated by application to the soil of urea, aqueous ammonia, or nitrogen compounds that release ammonia on decomposition. Both field observations and simulation experiments show that, when these events take place in forests of ectomycorrhizal trees, ectomycorrhizal fungi fruit during the late phase in the succession. Ectomycorrhizas are in fact observed in the soils colonized by these fungi. Among these fungi, Hebeloma spp., Laccaria spp., and a few others colonize commonly in various waste sites, while Hebeloma radicosum colonizes specifically in moles’ deserted middens (latrines) near their nests. The animals involved here as waste depositors or cadavers seem not to feed on the fungi and the plants but may depend on them for cleaning their own habitats, since mycorrhizas should readily remove products derived from wastes. The tripartite relationship described may be viewed as a cleaning symbiosis. Key words: animal waste, ammonia, postputrefaction fungi, Hebeloma, ectomycorrhiza, cleaning symbiosis.
Traditionally, soil evidence in forensic science has focused predominantly on the transference of soil particles from a victim
or suspect and a crime scene. However, a recent increase in forensic taphonomy research has highlighted the potential of soil
to provide key information to an investigation involving decomposed remains. A decomposing carcass can release a significant
pulse of nutrients into the surrounding soil (gravesoil) resulting in the retention of decomposition products in the soil
for a considerable period of time. In order to understand the complex associations between a decomposing carcass and the soil
system, research must be conducted in both controlled laboratory environments and outdoor field environments. This chapter
discusses two contrasting decomposition studies which aimed to investigate the cadaver/soil interaction. The first study investigated
the decomposition of small mouse carcasses buried in soil and was conducted within a controlled laboratory environment in
Western Australia. The second study investigated the decomposition of large pig carcasses placed on the soil surface and was
conducted in an outdoor field environment in southern Ontario. Both studies investigated a range of decomposition products
particularly focusing on carbon-based, nitrogen-based and phosphorus-based compounds as these were considered to offer the
most valuable information to address the research questions. The results of both studies provide the opportunity to comment
on the effect of carcass size, soil type and decomposition environment on the influx of decomposition products into the soil.
Forensic taphonomy is the use of processes associated with cadaver decomposition in the investigation of crime. For example,
these processes have been used to estimate post-mortem interval, estimate post-burial interval and locate clandestine graves.
In recent years, significant advances have provided a better understanding of cadaver decomposition and its effect on associated
soil (gravesoil). These are reviewed in the context of soil-based information. In this chapter, we consider the effect of
a cadaver on gravesoil and how these processes might be used in the legal system. In addition, we attempt to introduce the
idea of contrived, experimental work to forensic taphonomy.
Ungulate carcasses can have important effects on the surrounding soil and vegetation. The impact of six carcasses of European
bison (Bison bonasus) was investigated for the first time in a natural temperate forest (Białowieża, Poland) by measuring soil and plant nutrient
concentrations along a gradient extending from the centre of each carcass. Calcium concentration and pH were found to be higher
at the centre of the carcass, decreasing towards the periphery. This effect lasted up to 7years after the death of the animal.
The concentration of most nutrients in the soil and plants varied irregularly, suggesting an effect of the carcass at its
centre but the absence of a clear pattern of variation along the gradient. Concentrations of NO3− in the soil differed only at the 1-year old carcass, suggesting a fast turnover of nitrate in temperate forests. Our results
show that the effects of large herbivore carcasses on soil and plant nutrient concentrations are not easily detectable in
a temperate forest as in more homogeneous habitats, such as tundra and prairie. This may be due to the high activity of scavengers
and nutrient recycling in the study area, but it may also be a consequence of a more complex and patchy interaction between
nutrient availability and other limiting factors in temperate forests.
Two closely related chemoecological groups of fungi, the ammonia fungi and the postputrefaction fungi, have been associated with the decomposition by-products of cadavers. Sporocarps have been observed in disparate woodlands across the world and often mark sites of graves. These groups of fungi provide visible markers of the sites of cadaver decomposition and follow repeated patterns of successional change as apparent decomposition proceeds. We suggest these phenomena may become a useful tool for crime scene investigation, forensic archaeology and forensic taphonomy.
Forensic archaeologists and criminal investigators employ many different techniques for the location, recovery, and analysis of clandestine graves. Many of these techniques are based upon the premise that a grave is an anomaly and therefore differs physically, biologically, or chemically from its surroundings. The work reviewed in this communication demonstrates how and why field mycology might provide a further tool towards the investigation of scenes of crime concealed in forest ecosystems. The fruiting structures of certain fungi, the ammonia and the postputrefaction fungi, have been recorded repeatedly in association with decomposed mammalian cadavers in disparate regions of the world. The ecology and physiology of these fungi are reviewed briefly with a view to their potential as a forensic tool. This application of mycology is at an interface with forensic archaeology and forensic taphonomy and may provide a means to detect graves and has the potential to estimate postburial interval.
This is the first report on an ongoing study conducted to collect data on the specific insects that are found in association with decaying human cadavers. Four nude unembalmed human cadavers were each placed, at various times of the year, within a decay research facility located in open wooded area. Data were collected daily throughout the entire decay cycle on the various insect populations that frequented each cadaver. Analysis of the data shows that there is a direct correlation between the rate of decay and the succession of insect families and species found in association with a decaying cadaver. Application of this entomological information can contribute to a more accurate estimation of 'time since death' of an individual.
This paper reports a study of dog carcass communities near Knoxville, Tennessee. Special emphasis has been given to the insects. The principal portion of the field work was conducted between May 7, 1951, and May 14, 1952. A total of 43 dog carcasses yielded significant information concerning seasonal distribution of carrion insects and seral stages in carcass communities. Carcasses were placed at intervals of about 2 weeks in hot weather and less frequently during cooler weather. The standard procedure was to place carcasses in pairs with respect to date of placement. One member of each pair was placed on the ground in a wooded area and the other was placed in similar manner in a non-wooded (pasture) area; this pairing of carcasses was designed to permit comparison of carcass communities in wooded areas with those in non-wooded areas. Frequency of field trips varied from thrice daily (on certain occasions during the hottest weather) to once in 12 days (during a period of coldest weather). Usually, however, trips were made at intervals of one week or shorter. The type of operations performed upon visiting a carcass varied; important operations frequently included 1) recording physical condition of the carcass, 2) measuring air temperature and temperature under the carcass, 3) measuring pH of soil under the carcass, 4) counting various arthropods seen, or estimating their abundances according to a 5-term scale, and 5) collection of arthropods.
Microseral and seasonal variations in the carrion insect microcommunity were examined in 39 small-mammal carcasses in a red oak-basswood-sugar maple forest in Illinois from June 1968 through October 1969. Four stages of decomposition were described for the carcasses: Fresh, Bloat, Decay and Dry. These stages are the result of the activity of the arthropods, especially the insects. Four orders of arthropods (Coleoptera, Diptera, Hymenoptera and Acarina) accounted for over 90% of the organisms associated with carrion. The successional pattern of these arthropods on the carcass is discussed. Each of the major families found in the carrion microcommunity was represented by a few common species. Even though the families followed a fairly regular successional pattern, the species involved within a given family depended upon the season of the year. The specific times of abundance are discussed.
The decomposition of a human cadaver was stopped after solidification of putrefactive liquid during a GIS Burial experiment. Knowledge of this phenomenon is necessary to optimize burial conditions and to decrease cemetery congestion. In this preliminary study, we devised a method using thin-layer chromatography and gas chromatography to compare different putrefactive liquids. A comparison of lipid composition among two cadavers revealed a decrease in the decomposition rate of the cadaver that had the gelled putrefactive liquid. Essentially, fatty acids were observed in two types of extracts. The difference was quantitative: there was a higher amount of fatty acids in the gelled sample than in the standard liquid, suggesting a decrease of decomposition rate in the gelled extract. A large quantity of oleate salts may be favourable for solidification. In addition, an isomer of oleic acid (elaidic acid) could be present which may have a determining factor in the phenomenon of gelled putrefaction. A large amount of stearic acid was present in the gelled extract and may be involved in solidification. This method was efficient for comparing the lipid composition of different putrefactive liquids and may be used for a large-scale study. This is the first report concerning methods to determine the lipid composition of human decomposition liquids after 4 years postmortem.
http://www.crcpress.com/product/isbn/9781420069921
Forensic taphonomy is an applied discipline that is coming of age. To date,
however, the major advances in the field have been captured in publications
that deal primarily with the cadaver and associated items rather than the
grave itself. This book provides, for the first time, a collection of chapters
from leading scientists in their fields that deal primarily with the burial
environment. Our focus is on the processes of decomposition in soils, the
decomposers in the soil, and the basic physiochemical composition of the
soil as it relates to forensic science and taphonomy.
The book aims to provide the reader with an up-to-date overview of
fundamental scientific principles and methods used in forensic taphonomy
from a soils-based perspective. Soils are the materials that make up most
clandestine graves but are often given scant consideration. This is a shame,
as soils can contain an enormous amount of information within them—if
you know what to look for and how to find it. The purpose of this book is to
illuminate this search for forensic information in the soils generally and at
gravesites particularly. Of particular importance here is the detritusphere,
the soil immediately around the cadaver. This soil is the most altered by the
decomposition process and can contribute to the decomposition process.
Many biological and chemical effects of buried human remains can be found
here, and the analysis of soils around a cadaver for forensic use, though in its
infancy, is progressing apace.
The terrestrial environment has been much studied as a decomposition
environment for materials of little forensic value, such as leaf litter or dead
roots. These provide the basic methods and framework for studying and
understanding decomposition of materials in soils. It is only in recent years
that this has been applied to forensic taphonomy, in which studies have been
conducted with mammalian tissues and cadavers. The burial environment
is a complex and dynamic system of interdependent chemical, physical, and
biological processes. These processes influence, and are influenced by, the
inclusion of a body and its subsequent decay. Though this book deals with
what is known in this context, much still remains to be discovered, understood,
and applied to forensic science.
We believe this book is timely, as soils are receiving increased attention
as physical evidence. Thus far, the twenty-first century has seen an increase
of peer-reviewed publications related to soils and forensic science of at least
one third from the last decade of the twentieth century. We hope that this
book will provide a solid foundation for forensic taphonomists, anthropologists,
soil scientists, entomologists, bacteriologists, and mycologists who aim
to use the processes of cadaver decomposition in terrestrial ecosystems to
solve crime
The present study falls into two clearly defined parts, one dealing with the succession of carrion-frequenting organisms in dead guinea pigs, the other examining the influence of carrion on the typical soil fauna of a sclerophyll woodland.
Five different stages of carcass decomposition were recognized and these were correlated with the animal communities occupying them. These communities were contrasted with the community dwelling in the leaf litter and soil.
The various stages of decomposition affected the underlying soil differently, the greatest effect being observed during the "black putrefaction" and "butyric fermentation" stages. During the black putrefaction stage, body fluids which passed into the soil formed a cemented crust with the plant litter and the upper soil layer. The liquified decomposition products during the butyric fermentation stage destroyed the underlying plants as well as the soil fauna.
The decomposition resulted in the production of two distinct zones in the upper soil layers which differed both physically and in arthropod populations from a control area. The fauna of the "carrion zone", i.e. the area beneath the carcass, differed greatly from that of the control area. The fauna of the "intermediate zone", i.e. the belt surrounding the carrion 10 cm wide, also showed substantial differences. Only carrion dwellers were present in the carrion zone, whereas both these and soil dwellers were present in the intermediate zone. The decomposition of carrion had a marked effect on the soil fauna to a depth of 14 cm, but this was less drastic than in the upper soil layers. The reinvasion of the carrion zone by soil arthropods was not completed after a year. At the end of the study period, subterranean forms were better re-established than soil-surface or litter dwellers.
Very little is known about the microbiology of graves. We have taken the opportunity to investigate this subject by taking advantage of the unusual opportunity afforded by the experimental burial of pigs in a forensic experiment. Selected microbial characteristics of soils from the 0–15 and 15–30 cm depths of the graves of three pigs and of control soils have been determined 430 days after burial. The grave soils contained more total C, microbial biomass C and total N, and showed increased rates of respiration and N mineralisation compared to the control soils. The grave soils also had larger amino acid and NH 4 + concentrations, which was consistent with the increases in both net N mineralisation and pH values. Nitrification was not detected in any of the soils and the limited NO 3 − supply restricted the rate of denitrification, but the large alkali-soluble S 2− concentration of soils from the graves indicated reducing conditions in the graves. © 2000 Elsevier Science B.V. All rights reserved.
The results of an experiment conducted using photondensitometry to measure bone density are presented. The species examined are domestic and farmed wild pig (Susscrofa), domestic cattle (Bos taurus) and domestic sheep (Ovis aries). Inter-taxonomic variability and intra-taxonomic differences related to sex, age and breed are discussed. A comparison of the sheep density data published by Lyman (1982) and the data obtained in this research is made. Variability was noticed not only at inter-specific level but and most importantly at intra-specific level too, a fact indicating that large samples of skeletons of the same species should be examined if reliable results are to be obtained. The results are applied to archaeological materials from Britain putting particular emphasis on applying the two sets of sheep density data to the same assemblages and using separate density models for mature and immature pig specimens.
A laboratory experiment was conducted to determine the effect of temperature (2, 12, 22 °C) on the rate of aerobic decomposition of skeletal muscle tissue (Ovis aries) in a sandy loam soil incubated for a period of 42 days. Measurements of decomposition processes included skeletal muscle tissue mass loss, carbon dioxide (CO2) evolution, microbial biomass, soil pH, skeletal muscle tissue carbon (C) and nitrogen (N) content and the calculation of metabolic quotient (qCO2). Incubation temperature and skeletal muscle tissue quality had a significant effect on all of the measured process rates with 2 °C usually much lower than 12 and 22 °C. Cumulative CO2 evolution at 2, 12 and 22 °C equaled 252, 619 and 905 mg CO2, respectively. A significant correlation (P<0.001) was detected between cumulative CO2 evolution and tissue mass loss at all temperatures. Q10s for mass loss and CO2 evolution, which ranged from 1.19 to 3.95, were higher for the lower temperature range (Q10(2–12 °C)>Q10(12–22 °C)) in the Ovis samples and lower for the low temperature range (Q10(2–12 °C)<Q10(12–22 °C)) in the control samples. Metabolic quotient and the positive relationship between skeletal muscle tissue mass loss and cumulative CO2 evolution suggest that tissue decomposition was most efficient at 2 °C. These phenomena may be due to lower microbial catabolic requirements at lower temperature.
The ecology of soils associated with dead mammals (i.e. cadavers) is poorly understood. Although temperature and soil type are well known to influence the decomposition of other organic resource patches, the effect of these variables on the degradation of cadavers in soil has received little experimental investigation. To address this, cadavers of juvenile rats (Rattus rattus) were buried in one of three contrasting soils (Sodosol, Rudosol, and Vertosol) from tropical savanna ecosystems in Queensland, Australia and incubated at 29 °C, 22 °C, or 15 °C in a laboratory setting. Cadavers and soils were destructively sampled at intervals of 7 days over an incubation period of 28 days. Measurements of decomposition included cadaver mass loss, carbon dioxide–carbon (CO2–C) evolution, microbial biomass carbon (MBC), protease activity, phosphodiesterase activity, and soil pH, which were all significantly positively affected by cadaver burial. A temperature effect was observed where peaks or differences in decomposition that at occurred at higher temperature would occur at later sample periods at lower temperature. Soil type also had an important effect on some measured parameters. These findings have important implications for a largely unexplored area of soil ecology and nutrient cycling, which are significant for forensic science, cemetery planning and livestock carcass disposal.
The repeated introduction of an organic resource to soil can result in its enhanced degradation. This phenomenon is of primary importance in agroecosystems, where the dynamics of repeated nutrient, pesticide, and herbicide amendment must be understood to achieve optimal yield. Although not yet investigated, the repeated introduction of cadaveric material is an important area of research in forensic science and cemetery planning. It is not currently understood what effects the repeated burial of cadaveric material has on cadaver decomposition or soil processes such as carbon mineralization. To address this gap in knowledge, we conducted a laboratory experiment using ovine (Ovis aries) skeletal muscle tissue (striated muscle used for locomotion) and three contrasting soils (brown earth, rendzina, podsol) from Great Britain. This experiment comprised two stages. In Stage I skeletal muscle tissue (150 g as 1.5 g cubes) was buried in sieved (4.6 mm) soil (10 kg dry weight) calibrated to 60% water holding capacity and allowed to decompose in the dark for 70 days at 22 °C. Control samples comprised soil without skeletal muscle tissue. In Stage II, soils were weighed (100 g dry weight at 60% WHC) into 1285 ml incubation microcosms. Half of the soils were designated for a second tissue amendment, which comprised the burial (2.5 cm) of 1.5 g cube of skeletal muscle tissue. The remaining half of the samples did not receive tissue. Thus, four treatments were used in each soil, reflecting all possible combinations of tissue burial (+) and control (−). Subsequent measures of tissue mass loss, carbon dioxide-carbon evolution, soil microbial biomass carbon, metabolic quotient and soil pH show that repeated burial of skeletal muscle tissue was associated with a significantly greater rate of decomposition in all soils. However, soil microbial biomass following repeated burial was either not significantly different (brown earth, podsol) or significantly less (rendzina) than new gravesoil. Based on these results, we conclude that enhanced decomposition of skeletal muscle tissue was most likely due to the proliferation of zymogenous soil microbes able to better use cadaveric material re-introduced to the soil.
Identification of bacterial species and their metabolic activity may be useful in differentiating soil samples associated with forensic analyses of large animal carcasses. In this preliminary study, lipolytic and proetolytic soil bacteria were enumerated over the time course of decomposition of a swine carcass. A 60-kg pig was used because it resembles a human body in its fat distribution and cover of hair. Soil core-samples (grave-soil) were taken underneath the carcass every three days until day 15, and then sampled on days 28, 43, 57, and 71 between September and December 2008. Results indicated that lipolytic bacterial counts were initially the lowest at day 0 (before exposure) and increased to their highest between days 9 and 12 (active decomposition); they then decreased and leveled at days 15 through 71. Conversely, the proteolytic bacterial counts initially were the highest at day 0, slowly decreased at days 3 (fresh) and 6 (bloat) with a rapid decline at day 9 (active) followed by a second major decline at day 28 (advanced); they then leveled through the remaining time period. Of the 33 isolates that could be identified, 18 were in the genus Acinetobacter. The qPCR results using Group I lipase-specific primers followed a similar pattern as the lipolytic CFU observed.
This article reports results of a comparative study of decomposition rates of wild rabbit (Oryctolagus cuniculus) which were either (i) buried after exposure to insect activity, (ii) buried without exposure, (iii) kept above ground behind an insect screen, or (iv) continuously exposed above ground in a field experiment. Results showed that dipteran oviposition occurred consistently in groups i and iv only. Decomposition rates (measured by Total Body Score every c. 50 accumulated degree days [ADD]) of rabbits kept behind the screen and those buried without exposure showed no difference (p = 0.450). This was significantly slower than those buried after exposure (p = 0.0016) which was in turn significantly slower than those continuously exposed (p < 0.001). Temperatures collected from animals showed the presence of feeding larvae increased intra-abdominal temperatures to >5 degrees C above ambient. The findings support the assertion that insect presence is the primary agent affecting decomposition rate via tissue consumption and also the heat they generate.
This study compared total body score (TBS) in buried remains (35 cm depth) with and without insect access prior to burial. Sixty rabbit carcasses were exhumed at 50 accumulated degree day (ADD) intervals. Weight loss, TBS, intra-abdominal decomposition, carcass/soil interface temperature, and below-carcass soil pH were recorded and analyzed. Results showed significant differences (p < 0.001) in decomposition rates between carcasses with and without insect access prior to burial. An approximately 30% enhanced decomposition rate with insects was observed. TBS was the most valid tool in postmortem interval (PMI) estimation. All other variables showed only weak relationships to decomposition stages, adding little value to PMI estimation. Although progress in estimating the PMI for surface remains has been made, no previous studies have accomplished this for buried remains. This study builds a framework to which further comparable studies can contribute, to produce predictive models for PMI estimation in buried human remains.
Forensic taphonomy involves the use of decomposition to estimate postmortem interval (PMI) or locate clandestine graves. Yet, cadaver decomposition remains poorly understood, particularly following burial in soil. Presently, we do not know how most edaphic and environmental parameters, including soil moisture, influence the breakdown of cadavers following burial and alter the processes that are used to estimate PMI and locate clandestine graves. To address this, we buried juvenile rat (Rattus rattus) cadavers (approximately 18 g wet weight) in three contrasting soils from tropical savanna ecosystems located in Pallarenda (sand), Wambiana (medium clay), or Yabulu (loamy sand), Queensland, Australia. These soils were sieved (2mm), weighed (500 g dry weight), calibrated to a matric potential of -0.01 megapascals (MPa), -0.05 MPa, or -0.3 MPa (wettest to driest) and incubated at 22 degrees C. Measurements of cadaver decomposition included cadaver mass loss, carbon dioxide-carbon (CO(2)-C) evolution, microbial biomass carbon (MBC), protease activity, phosphodiesterase activity, ninhydrin-reactive nitrogen (NRN) and soil pH. Cadaver burial resulted in a significant increase in CO(2)-C evolution, MBC, enzyme activities, NRN and soil pH. Cadaver decomposition in loamy sand and sandy soil was greater at lower matric potentials (wetter soil). However, optimal matric potential for cadaver decomposition in medium clay was exceeded, which resulted in a slower rate of cadaver decomposition in the wettest soil. Slower cadaver decomposition was also observed at high matric potential (-0.3 MPa). Furthermore, wet sandy soil was associated with greater cadaver decomposition than wet fine-textured soil. We conclude that gravesoil moisture content can modify the relationship between temperature and cadaver decomposition and that soil microorganisms can play a significant role in cadaver breakdown. We also conclude that soil NRN is a more reliable indicator of gravesoil than soil pH.
This study considered annual, seasonal and shorter term variation in patterns of insect succession onto decomposing remains at two contrasting locations in Western Australia, bushland and agricultural. The degree of consistency in insect succession patterns over spatial and temporal scales was evaluated through multivariate analysis of occurrence-based distance matrices. Insect assemblages were strongly correlated between locations, within corresponding time periods, indicating that patterns of insect succession were similar between localised sites within the same broad geographic area. This suggests that there is reasonable scope for the application of baseline succession data generated at a single study site to a range of decomposition sites within a given region. Differences were largely due to species absences at the agricultural site. Three species of Coleoptera were identified as possible representatives of bushland habitat, Ptomaphila lacrymosa (Silphidae), Omorgus tatei (Trogidae) and Helea castor (Tenebrionidae), and may be indicative of post mortem movement between habitat types. Within locations, variation in insect assemblages was not significant between years. Within years, insect assemblages varied significantly over time on a seasonal time scale and as decomposition progressed through defined decomposition stages. Forensically relevant data detailing the seasonal pattern of insect succession onto decomposing remains for Western Australia are reported. Additional focus has been directed towards hymenopteran parasitoids that frequent decomposing remains and parasitise Diptera colonisers. Parasitoids can be used to provide an extended PMI timeframe in cases where traditional forensic indicators have completed their development.
A carrion study of the baby pig, Sus scrofa Linnaeus, was conducted during the summers of 1962 and 1963 in a mixed mesophytic hardwood-pine community at Clemson, South Carolina. Six stages of decomposition were delimited for carrion exposed to arthropods: fresh, bloated, active decay, advanced decay, dry, and remains. Five stages were recognized for carrion protected from arthropods: fresh, bloating and decomposition, flaccidity and dehydration, mummy, and desiccation and disintegration. Carrion free of insects decomposed and dried very slowly, retaining its form for many months, while 90% of the carrion open to insects was removed in 6 days. Carrion temperature during the bloated through advanced decay stages differed widely from that of air or soil. A definite ecological succession occurred among the fauna of carrion. Each stage of decay was characterized by a particular group of arthropods, each of which occupied a particular niche. Their activities were influenced by physical properties of carrion, rapidity of putrefaction, time of day, and weather. A total and 522 species representing 3 phyla, 9 classes, 31 orders, 151 families, and 359 genera were collected from decomposing pigs. Four orders of arthropods (Coleoptera, Diptera, Hymenoptera, and Araneida) accounted for 78% of the carrion fauna. Two coleopterous families, Histeridae and Staphylinidae and three dipterous families, Sarcophagidae, Calliphoridae, and Muscidae, represented 26% of the fauna.
Thesis (Ph. D.)--Northwestern University, 1970. Includes bibliographical references (leaves 85-93). Photocopy.
Little is known about the effect of edaphic conditions on the decomposition of buried mammalian tissues. To address this, we set up a replicated incubation study with three fresh soils of contrasting pH: a Podsol (acidic), a Cambisol (neutral), and a Rendzina (alkaline), in which skeletal muscle tissue (SMT) of known mass was allowed to decompose. Our results clearly demonstrated that soil type had a considerable effect on the decomposition of SMT buried in soil. Differences in the rate of decomposition were up to three times greater in the Podsol compared with the Rendzina. The rate of microbial respiration was correlated to the rate of soft tissue loss, which suggests that the decomposition of SMT is dependent on the microbial community present in the soil. Decompositional by-products caused the pH of the immediate soil environment to change, becoming more alkaline at first, before acidifying. Our results demonstrate the need for greater consideration of soil type in future taphonomic studies.
The study of decaying organisms and death assemblages is referred to as forensic taphonomy, or more simply the study of graves. This field is dominated by the fields of entomology, anthropology and archaeology. Forensic taphonomy also includes the study of the ecology and chemistry of the burial environment. Studies in forensic taphonomy often require the use of analogues for human cadavers or their component parts. These might include animal cadavers or skeletal muscle tissue. However, sufficient supplies of cadavers or analogues may require periodic freezing of test material prior to experimental inhumation in the soil. This study was carried out to ascertain the effect of freezing on skeletal muscle tissue prior to inhumation and decomposition in a soil environment under controlled laboratory conditions. Changes in soil chemistry were also measured. In order to test the impact of freezing, skeletal muscle tissue (Sus scrofa) was frozen (-20 degrees C) or refrigerated (4 degrees C). Portions of skeletal muscle tissue (approximately 1.5 g) were interred in microcosms (72 mm diameter x 120 mm height) containing sieved (2mm) soil (sand) adjusted to 50% water holding capacity. The experiment had three treatments: control with no skeletal muscle tissue, microcosms containing frozen skeletal muscle tissue and those containing refrigerated tissue. The microcosms were destructively harvested at sequential periods of 2, 4, 6, 8, 12, 16, 23, 30 and 37 days after interment of skeletal muscle tissue. These harvests were replicated 6 times for each treatment. Microbial activity (carbon dioxide respiration) was monitored throughout the experiment. At harvest the skeletal muscle tissue was removed and the detritosphere soil was sampled for chemical analysis. Freezing was found to have no significant impact on decomposition or soil chemistry compared to unfrozen samples in the current study using skeletal muscle tissue. However, the interment of skeletal muscle tissue had a significant impact on the microbial activity (carbon dioxide respiration) and chemistry of the surrounding soil including: pH, electroconductivity, ammonium, nitrate, phosphate and potassium. This is the first laboratory controlled study to measure changes in inorganic chemistry in soil associated with the decomposition of skeletal muscle tissue in combination with microbial activity.
This study was conducted to collect data on specific volatile fatty acids (produced from soft tissue decomposition) and various anions and cations (liberated from soft tissue and bone), deposited in soil solution underneath decomposing human cadavers as an aid in determining the "time since death." Seven nude subjects (two black males, a white female and four white males) were placed within a decay research facility at various times of the year and allowed to decompose naturally. Data were amassed every three days in the spring and summer, and weekly in the fall and winter. Analyses of the data reveal distinct patterns in the soil solution for volatile fatty acids during soft tissue decomposition and for specific anions and cations once skeletonized, when based on accumulated degree days. Decompositional rates were also obtained, providing valuable information for estimating the "maximum time since death." Melanin concentrations observed in soil solution during this study also yields information directed at discerning racial affinities. Application of these data can significantly enhance "time since death" determinations currently in use.
Much of the difficulty in determining the time since death stems from the lack of systematic observation and research on the decomposition rate of the human body. Continuing studies conducted at the University of Tennessee, Knoxville, provide useful information on the impact of carrion insect activity, ambient temperature, rainfall, clothing, burial and depth, carnivores, bodily trauma, body weight, and the surface with which the body is in contact. This paper reports findings and observations accumulated during eight years of research and case studies that may clarify some of the questions concerning bodily decay.
Understanding the processes of postmortem change in biologic systems is important to the forensic sciences. Previous experimental studies of postmortem change in animals under field conditions made use of animal carcasses that had been incidentally exposed to the effects of freezing and thawing or mechanical damage, or both, and were limited to gross observations. The current study was designed to document intrinsic processes of postmortem change, and the effects of freezing-thawing and mechanical injury, under controlled conditions in the field, using histologic and microbiologic techniques, as well as gross observation. Insect and microbiologic succession sequences, and patterns of decomposition and disarticulation, were observable over time. Previously frozen-thawed animals showed predominantly decay (aerobic decomposition) in the field, while freshly killed animals showed predominantly putrefaction (anaerobic decomposition). Previously frozen animals showed the same sequence, but accelerated rates, of disarticulation. Mechanically injured tissues showed accelerated rates of decomposition. These findings have implications for the interpretation of results of previous studies, as well as the interpretation of human and animal remains subjected to freezing and thawing.
The decomposition of a human cadaver was stopped after solidification of putrefactive liquid during a GIS Burial experiment. Knowledge of this phenomenon is necessary to optimize burial conditions and to decrease cemetery congestion. In this preliminary study, we devised a method using thin-layer chromatography and gas chromatography to compare different putrefactive liquids. A comparison of lipid composition among two cadavers revealed a decrease in the decomposition rate of the cadaver that had the gelled putrefactive liquid. Essentially, fatty acids were observed in two types of extracts. The difference was quantitative: there was a higher amount of fatty acids in the gelled sample than in the standard liquid, suggesting a decrease of decomposition rate in the gelled extract. A large quantity of oleate salts may be favourable for solidification. In addition, an isomer of oleic acid (elaidic acid) could be present which may have a determining factor in the phenomenon of gelled putrefaction. A large amount of stearic acid was present in the gelled extract and may be involved in solidification. This method was efficient for comparing the lipid composition of different putrefactive liquids and may be used for a large-scale study. This is the first report concerning methods to determine the lipid composition of human decomposition liquids after 4 years postmortem.
We established a database of insect succession on buried carrion in two biogeoclimatic zones of British Columbia over a 16-month period beginning June 1995. Pig (Sus scrofa L.) carcasses were buried shortly after death in the Coastal Western Hemlock and Sub-boreal Spruce biogeoclimatic zones of British Columbia. Buried pigs exhibited a distinct pattern of succession from that which occurred on above-ground carrion. The species composition and time of colonization for particular species differed between the two zones. Therefore ideally, a database of insect succession on buried carrion should be established for each major biogeoclimatic zone. We did not observe maggot masses on any of the buried carcasses; therefore, the presence of maggot masses may indicate a delayed burial. Soil temperature was a better indicator of internal buried carcass temperature (r2 = 0.92, p < 0.0001) than was ambient air temperature (r2 = 0.60, p < 0.0001); thus soil temperature should be used to determine developmental rates of insects for determination of the postmortem interval by a forensic entomologist.
In a murder investigation, where the victim had been strangled and buried in a shallow grave, there were discrepancies between the post mortem interval (PMI) as estimated from entomological studies and estimations determined from other evidence. This inconsistency provided the impetus for examining the decay process using pig carcasses as analogues for the human cadaver. The pigs were buried in the immediate vicinity of the original burial site in December 1996, which was the month when the victim was purported to have been interred in the previous year. The buried pigs were then monitored for 5 months which, based on the evidence other than the entomological, was the period over which the corpse was thought to have lain in the ground. The pig corpses were disturbed by scavengers in mid April: this was the same time that the human corpse was discovered in the previous year by scavengers. Insects played no role in the decomposition process until the pig carcasses had been exposed by animals. Blowflies, notably Calliphora vomitoria, were attracted to the exposed tissues and laid eggs from which larvae developed. Calliphora vomitoria is a species often used to estimate PMI. This investigation has shown that soil conditions and low seasonal temperatures had preserved the pig carcasses for longer than might be expected. Using the blowfly larvae to estimate PMI would have produced erroneous results had not the burial environment and exhumation history been investigated.
Soil samples recovered from grave exhumations have been analysed in an attempt to identify and characterise adipocere contained in the samples. The soil samples were collected from different environments, including samples recovered from forensic grave sites. Gas chromatography-mass spectrometry (GC-MS) was employed to identify adipocere and characterise the fatty acid composition. X-ray diffraction was used to characterise the soil environments.
A controlled laboratory experiment is described, in principle and practice, which can be used for the of determination the rate of tissue decomposition in soil. By way of example, an experiment was conducted to determine the effect of temperature (12 degrees, 22 degrees C) on the aerobic decomposition of skeletal muscle tissue (Organic Texel x Suffolk lamb (Ovis aries)) in a sandy loam soil. Measurements of decomposition processes included muscle tissue mass loss, microbial CO2 respiration, and muscle tissue carbon (C) and nitrogen (N). Muscle tissue mass loss at 22 degrees C always was greater than at 12 degrees C (p < 0.001). Microbial respiration was greater in samples incubated at 22 degrees C for the initial 21 days of burial (p < 0.01). All buried muscle tissue samples demonstrated changes in C and N content at the end of the experiment. A significant correlation (p < 0.001) was demonstrated between the loss of muscle tissue-derived C (Ct) and microbially-respired C (Cm) demonstrating CO2 respiration may be used to predict mass loss and hence biodegradation. In this experiment Q10 (12 degrees C-22 degrees C) = 2.0. This method is recommended as a useful tool in determing the effect of environmental variables on the rate of decomposition of various tissues and associated materials.
This study, conducted at the University of Tennessee's Anthropological Research Facility (ARF), describes the establishment of the Decompositional Odor Analysis (DOA) Database for the purpose of developing a man-portable, chemical sensor capable of detecting clandestine burial sites of human remains, thereby mimicking canine olfaction. This "living" database currently spans the first year and a half of burial, providing identification, chemical trends and semi-quantitation of chemicals liberated below, above and at the surface of graves 1.5 to 3.5 ft deep (0.45 to 1.0 m) for four individuals. Triple sorbent traps (TSTs) were used to collect air samples in the field and revealed eight major classes of chemicals containing 424 specific volatile compounds associated with burial decomposition. This research is the first step toward identification of an "odor signature" unique to human decomposition with projected ramifications on cadaver dog training procedures and in the development of field portable analytical instruments which can be used to locate human remains buried in shallow graves.
Adipocere is a soft white substance formed postmortem from fatty tissue in a decomposing body. In this preliminary study the formation of adipocere in soil was investigated for a number of animal species. Adipocere was formed from the fatty tissue of pig, cattle, sheep and rabbit. It was found that adipocere did not form from the fatty tissue of chicken or kangaroo in the time frame investigated. The issues being considered are relevant to the forensic examination of remains whose origin is otherwise uncertain or which are, in some way, related to human remains. Infrared spectroscopy and gas chromatography-mass spectrometry were used to characterise the composition of adipocere formed in the various species after different burial durations. Adipocere was observed to form at different rates among the species, but there was no distinct evidence of the fundamental composition varying between species.
A controlled laboratory experiment was conducted in order to investigate the effect of the method of burial (i.e. the presence of coffin and clothing) on the formation of adipocere. This study follows previous studies by the authors who have investigated the effect of physical conditions on the formation of adipocere present in a controlled burial environment. The study utilises infrared spectroscopy to provide a preliminary lipid profile of the remains following a 12 month decomposition period. Inductively coupled plasma-mass spectrometry was employed as a technique for determining the salts of fatty acids present in adipocere. Gas chromatography-mass spectrometry (GC-MS) was used as the confirmatory test for the identification and determination of the chemical composition of adipocere which formed in the controlled burial environments. The results suggest that coffins will retard the rate at which adipocere forms but that clothing enhances its formation. The results concur with previous observations on adipocere formation in burial environments.
Adipocere refers to a postmortem product which forms from body fat in the later stages of decomposition. Factors present in the surrounding decomposition environment will influence adipocere formation and may accelerate or retard the process of conversion. One such factor important in burial environments is the type of grave soil in which the burial has taken place. This study was conducted to investigate the influence of various soil types on the formation of adipocere in grave soils. X-ray diffraction and particle size analysis were used to characterise the soils which were essentially chosen on the basis of grain size. Infrared spectroscopy, inductively coupled plasma-mass spectrometry, and gas chromatography-mass spectrometry were used to investigate the lipid profile and chemical composition of adipocere developed from decomposing tissue. The results suggest that adipocere is able to form in various soil types and that particular soil environments may accelerate its formation.