Figure 2 - uploaded by Alex Capaldi
Content may be subject to copyright.
Time captures of one realization of the metapopulation model using a 100-patch grid and parameter set 1 from Table 2. The top row of images is heat maps of human population density while the bottom row represents the mammoth population. Dark blue represents low population density while red is high density. The images (from left to right) were taken at t = 1, t = 1.7, and t = 2.4 years. Mammoths went globally extinct at t = 2.5 years for this realization.
Source publication
One extinction hypothesis of the Columbian mammoth (Mammuthus columbi), called overkill, theorizes that early humans overhunted the animal. We employ two different approaches to test this hypothesis mathematically: analyze the stability of the equilibria of a 2D ordinary differential equations (ODE) system and develop a metapopulation differential...
Similar publications
A tubular bone bead dating to ~ 12,940 BP was recovered from a hearth-centered activity area at the La Prele Mammoth site in Converse County, Wyoming, USA. This is the oldest known bead from the Western Hemisphere. To determine the taxonomic origin of the bead, we extracted collagen for zooarchaeology by mass spectrometry (ZooMS). We also used micr...
Archaeologists have long subjected Clovis megafauna kill/scavenge sites to the highest level of scrutiny. In 1987, a Columbian mammoth (Mammuthus columbi) was found in spatial association with a small artifact assemblage in Converse County, Wyoming. However, due to the small tool assemblage, limited nature of the excavations, and questions about th...
This paper is a multi-disciplinary review of the Northern Tutchone oral history concerning encounters with Woolly Mammoths in their traditions. A comparison is made with similar traditions of other North American indigenous people, and this is reviewed against evidence for the existence and hunting of woolly mammoth in North America. The Ice Age ge...
Citations
... Existing mechanistic models applied to megafauna systems differ in their complexity, ranging from predator-prey models (Frank et al., 2015;Nogués-Bravo et al., 2008), to fully age-structured stochastic models (Prowse et al., 2013), or stochastic predator-prey-competition functions (Prowse et al., 2014). If sufficiently comprehensive, such models can be useful tools to compare the likelihood of the processes driving extinctions, even in the deeper past. ...
The causes of Sahul’s megafauna extinctions remain uncertain, although several interacting factors were likely responsible. To examine the relative support for hypotheses regarding plausible ecological mechanisms underlying these extinctions, we constructed the first stochastic, age-structured models for 13 extinct megafauna species from five functional/taxonomic groups, as well as eight extant species within these groups for comparison. Perturbing specific demographic rates individually, we tested which species were more demographically susceptible to extinction, and then compared these relative sensitivities to the fossil-derived extinction chronology. Our models show that the macropodiformes were the least demographically susceptible to extinction, followed by carnivores, monotremes, vombatiform herbivores, and large birds. Five of the eight extant species were as or more susceptible than the extinct species. There was no clear relationship between extinction susceptibility and the extinction chronology for any perturbation scenario, while body mass and generation length explained much of the variation in relative risk. Our results reveal that the actual mechanisms leading to the observed extinction chronology were unlikely related to variation in demographic susceptibility per se, but were possibly driven instead by finer-scale variation in climate change and/or human prey choice and relative hunting success.
... The megafaunal extinction at the end of the Quaternary is of global interest as a possible means to aid our understanding of the patterns of modern extinctions, although the exact reasons for this extinction are still debated. Many causal factors have been proposed for the megafaunal extinction, with the main controversy focusing on the relative importance of either climatic or anthropogenic impacts (Guthrie, 1984;Alroy, 2001;Grayson and Meltzer, 2003;Frank et al., 2015;Surovell et al., 2016). However, it is well established that coprophilous fungi can serve as a proxy to aid in documenting the former presence of megafauna in the region when their body fossils are not present (Davis, 1987;Davis and Shafer, 2006;Doyen and Etienne, 2017;Perrotti and Van Asperen, 2019). ...
... The cause of these extinctions remains the subject of intense debate. Disagreement concerns the relative impacts of human hunting (Martin 1984;Alroy 2001;Surovell and Waguespack 2009;Frank et al. 2015;Surovell et al. 2016), climate change (Guthrie 1984;Grayson and Meltzer 2003), disease (MacPhee 1997) and a potential extraterrestrial impact (Firestone et al. 2007) on Pleistocene megafauna. ...
The use of spores of coprophilous fungi from sedimentary sequences as proxy evidence for large herbivore abundance has garnered pronounced attention and scrutiny over the past three decades. In response to the rapid rate at which new information is being discovered on this topic, this paper presents a brief review of the archaeological applications so far, and outlines opportunities and limitations of using Sporormiella as a proxy for herbivore abundance. Specific archaeological uses of this proxy include understanding megaherbivore extinctions and human land use patterns such as pastoralism and agriculture. We analyse how dung fungal records are formed and review the mycological literature to outline factors affecting spore reproduction and preservation. These include how strongly each commonly used dung fungal taxon relies on dung as a substrate and environmental factors affecting dung fungal reproduction and coprophilous fungi deposition. Certain laboratory preparation techniques adversely affect spore representation on pollen slides. The methods of analysis and quantification of spore records also impact our understanding. We describe good practice to increase precision of analytical methods. Due to limitations imposed by some of these factors, it is possible that an absence of dung fungi from a palaeoecological record does not imply an absence of herbivores. However, consideration of these factors and inclusion of as wide a range of coprophilous spore records as possible increases the reliability of such inferences.
... Statistical analysis of the radiocarbon record has demonstrated that end Pleistocene extinctions in North America occurred so rapidly; they were geologically simultaneous (Faith and Surovell, 2009). Additional mathematical models involving parameters such as prey choice, patch choice and mammal population stability consistently demonstrate that even a small increase in predatory behavior (such as that by humans) could increase death rates enough to decimate a population of slow breeding mammals (Grund et al., 2012;Frank et al., 2015). Another simulation by Araujo et al. (2015) acknowledges that climate change probably stressed large mammal communities, but that human arrival was a necessary factor to cause extinctions. ...
Two cores from the Page-Ladson archaeological site, Florida were analyzed for pollen and the dung fungus Sporormiella. The cores contained stratified deposits spanning the Pleistocene-Holocene transition: a period characterized by the widespread extinction of Pleistocene megafauna and abrupt changes in vegetation type and distribution. The disappearance of Sporormiella, a well-established proxy for large herbivore abundance, by ~12,700 cal BP is consistent with the timing of Terminal Pleistocene megafaunal extinction elsewhere in North America. However, a resurgence of Sporormiella between ~10,750-10,200 cal BP suggests an Early Holocene incursion of extant megaherbivores such as bison. Pollen evidence from the site also reflects dramatic vegetation changes, which are likely a response to both changing climate and fluctuating herbivore populations. Prior to 14,500 cal BP, the pollen assemblage reflects a relatively cool and dry climate. Between ca. 14,500-12,600 cal BP, the sediments are characterized by an increase in hardwood forest and mesic plant taxa, indicating an increase in both temperature and precipitation. After 12,600 cal BP, a decrease in arboreal pollen, with the exception of oak, alongside an increase in herbaceous pollen, indicates drier, warmer conditions. These results contextualize changes in human behavior at the onset of the Holocene.
... These unrealistic fractions could lead to erroneous results such as when extinction is not declared due to the mammoth population persisting a mere fraction of an individual above the extinction criterion. (3) Finally, the human and mammoth migration rates in the model were assumed and not based on literature values (Frank et al., 2015). ...
... First, we reproduce here the ODE metapopulation human-mammoth model first used by Frank et al. (2015). Next, we will describe how we constructed our discrete stochastic analogue of the ODE model. ...
The cause of the extinction of the Columbian mammoth (Mammuthus columbi) and other species of megafauna during the end of the Pleistocene epoch is an ongoing debate. In this study, we used mathematical modelling to test the overkill hypothesis first proposed by Martin in 1973. The overkill hypothesis claims that early humans migrating from Asia through Beringia and into North America hunted the majority of the continent’s megafauna to extinction. Previous research has been conducted on the overkill hypothesis for the Columbian mammoth using a continuous differential equations model. We improved on this work by developing a computationally more efficient and more realistic discrete stochastic model. Most model parameters were obtained directly from the literature; migration parameters were informed by the literature and calibrated for the model. Our results provide evidence in support of the overkill hypothesis.
... In spite of their analytical and predictive value, mathematical models have been used only sporadically, although increasingly, in deconstructing causal factors driving the dynamics of palaeoecological and archaeological processes (see e.g. Birks, 1985;Flores, 1998Flores, , 2014Brantingham and Kuhn, 2001;Banks et al., 2006Banks et al., , 2008Holmes, 2007;Lycett and von Cramon-Taubadel, 2008;Steele, 2009;Griffith et al., 2010;Stiner et al., 2010;Barton et al., 2011;Sørensen, 2011, Rodríguez-G omez et al., 2012Wales, 2012;Romanowska, 2014;Frank et al., 2015;Peart, 2015;Yule et al., 2014;Romanowska et al., in press). This is in particular true with regard to dispersal, dispersion and settlement of hominin ...
This paper reviews the history of human economic activity from the time Homo sapiens appeared to the present. The first aim is to provide a coherent narrative of the economic history of this period. The second aim is to quantify economic activities where time series data is available and to use economic theory to explain the trends and turning points. It examines the history of three central time series – the aggregate human population, output per capita and human‐induced species extinctions. It concludes with some brief observations on the contribution of Big Economic History to Big Human History.
