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Age estimation in infant and prenatal individuals through the metric development of the pars petrosa and squamosal portion of the temporal bone

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Erik Borja Miranda at University of Granada
Erik Borja Miranda
Manuel Partido Navadijo at Universidad de Sevilla
Manuel Partido Navadijo
Inma Aleman at University of Granada
Inma Aleman
Javier Irurita at University of Granada
Javier Irurita
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Abstract and Figures

This study proposes an assessment of the accuracy of the Fazekas and Kósa and Nagaoka methods by measuring the squamosal and petrous portions of the temporal bone, whose application in the Mediterranean population is not recommended. Therefore, our proposal is a new formula to estimate the age of skeletal remains from individuals at 5 months gestational age to 1.5 postnatal years with the temporal bone. The proposed equation was calculated on a Mediterranean sample identified from the cemetery of San José, Granada (n = 109). The mathematical model used is the exponential regression of the estimated age for each measure and sex, and both in combination, using an inverse calibration and cross-validation model. In addition, the estimation errors and the percentage of individuals within a 95% confidence interval were calculated. The lateral development of the skull, especially the growth of the length of the petrous portion, showed the greatest accuracy, while its counterpart, the width of the pars petrosa, showed the lowest accuracy, so its use is discouraged. The positive results from this paper should be useful in both forensic and bioarchaeological contexts.
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International Journal of Legal Medicine (2023) 137:1505–1514
https://doi.org/10.1007/s00414-023-03030-0
ORIGINAL ARTICLE
Age estimation ininfant andprenatal individuals throughthemetric
development ofthepars petrosa andsquamosal portion
ofthetemporal bone
ErikA.BorjaMiranda1 · ManuelPartidoNavadijo1 · InmaculadaAlemánAguilera1 · JavierIruritaOlivares1
Received: 10 February 2023 / Accepted: 22 May 2023 / Published online: 8 June 2023
© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023
Abstract
This study proposes an assessment of the accuracy of the Fazekas and Kósa and Nagaoka methods by measuring the squa-
mosal and petrous portions of the temporal bone, whose application in the Mediterranean population is not recommended.
Therefore, our proposal is a new formula to estimate the age of skeletal remains from individuals at 5 months gestational
age to 1.5 postnatal years with the temporal bone. The proposed equation was calculated on a Mediterranean sample identi-
fied from the cemetery of San José, Granada (n = 109). The mathematical model used is the exponential regression of the
estimated age for each measure and sex, and both in combination, using an inverse calibration and cross-validation model.
In addition, the estimation errors and the percentage of individuals within a 95% confidence interval were calculated. The
lateral development of the skull, especially the growth of the length of the petrous portion, showed the greatest accuracy,
while its counterpart, the width of the pars petrosa, showed the lowest accuracy, so its use is discouraged. The positive results
from this paper should be useful in both forensic and bioarchaeological contexts.
Keywords Age estimation· Forensic anthropology· Non-adults individuals· Temporal bone· Regression analysis
Introduction
The development of methods to estimate the age of indi-
viduals represents a considerable part of the physical and
forensic anthropology literature, because the identification
of human skeletal remains is one of the basic aspects of the
subject of the field [1]. In the case of infant skeletal remains,
the constant development, growth, and maturation of the
skeleton and teeth make it possible to estimate the age at
death with a high degree of reliability [2, 3]. That is why
the length of the long bones and dental development and
eruption have usually been employed to estimate the age of
infant individuals [4–6].
Most of the current methods used to estimate the age
of non-adult individuals are far from following the recom-
mendations of the scientific community for publication in
terms of sample size, reliability, and error estimation, among
other factors [7]. While these approaches offer a substantial
amount of information regarding the growth and develop-
ment of individual skeletal elements, it is essential that the
new methods proposed by researchers are not only more
precise in their mathematical expression, but also easier to
use by the anthropologist [8].
The development of the skull as a criterion for age esti-
mation in non-adult individuals is quite useful especially in
early childhood, given the large number of bones in the cra-
nial structure and their different stages of fusion. The fetal
growth of the temporal bone was described by Anson [9] and
has been used to estimate age in several studies [10–15]. The
lateral region of the temporal bone, including the squamous
portion, shows very rapid growth between birth and 4 years
of age. Although it continues to grow until approximately
20 years of age, this development is drastically reduced with
respect to the first years of life [16]. Another favorable aspect
INFO: The main author is under 35; as indicated in the “Supporting
Junior Scientists” section, I communicated this to the editors’
council.
* Erik A. Borja Miranda
erikborm@gmail.com
1 Laboratory ofAnthropology, Department ofLegal Medicine,
Toxicology andPhysical Anthropology, University
ofGranada, Avda. de la Investigación, 11, 18006Granada,
Spain
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Cranial fractures seldom occur after minor trauma in a child. Several studies showed that accidents at home (falls from the parents' arms, changing table, or bed) rarely induce fractures of the skull and associated intracranial lesions (Bonnier et al., 1996;Paddock et al., 2017b) (Table 1). ...
... Borja Miranda et al. (2023) evaluated the accuracy of Fazekas and Kόsa's (1978) method for age estimation based on the growth of the pars petrosa (temporal bone) on an identified contemporary population of non-adult individuals at 5 months gestational age to 1.5 postnatal years (n ¼ 109 from a cemetery in Granada). Firstly, they concluded that this Fazekas and Kόsa's method is not applicable to the Mediterranean population. ...
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... As exclusion criteria, the following individuals were discarded: individuals of unknown age at death, those who were mummified, those whose antemortem records indicated prematurity, since their underdevelopment could imply an anomalous formation and/or development [19], and those individuals in whom the scapulas were absent. In the individuals whose scapulas were affected by taphonomic factors, only measurements of the scapular region that was undamaged were taken. ...
Validation of age estimation methods through the scapula in a Mediterranean non-adult population
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Age estimation methods through the metric study of bones in non-adult individuals are a frequently used tool in Biological and Forensic Anthropology; however, few methodological validation studies are available, given the limited number of adequate samples for their study. In this context, the aim of this work is to test the effectiveness of the methods of Fazekas and Kósa (1978), Saunders et al. (1993), Rissech and Black (2007) and Cardoso et al. (2017), for age estimation through the measurements of the scapula, in the non-adult osteological collection of the Anthropology Laboratory of the University of Granada (Spain), one of the most representative identified non-adult collections internationally. For this purpose, nine different measurements of the scapula were taken from a total of 149 non-adult individuals, applying the regression formulae proposed by the different authors and verifying their accuracy. Results have shown the existence of significant differences between the real age and the estimated age in almost all the tested methods, with degrees of error that differ from those obtained in the original study populations. Based on the obtained results, it is recommended to use the method of Cardoso et al. in postnatal individuals, always adjusting the degrees of error with those obtained in this work.
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Purpose This study aims to establish a population-specific age estimation model by investigating the correlation between the volume of the right first permanent molar pulp chamber and the actual age of Chinese Han adults. Method A total of 1857 CBCT images of Han adult teeth (883 males, 974 females) from the Department of Stomatology of the Affiliated Hospital of North Sichuan Medical College were collected. The volume of the right first permanent molar pulp chamber was measured using Mimics software for statistical analysis. The data were divided into a training set and a validation set in an 8:2 ratio. An age estimation model was built using 1485 samples from the training set, and the accuracy of the model was verified with 372 samples. Results The volume of the right upper and lower jaw pulp chambers showed a strong negative correlation with age, with the correlation of the upper jaw volume with age being superior to that of the lower jaw, and the correlation was highest in the upper jaw of females (r = 0.880). There was a significant difference in the volume of the right first permanent molar pulp chamber between the upper and lower teeth positions and sexes (P < 0.05). Among the 11 mathematical models constructed, the cubic regression model was superior to the other models, and the cubic regression model built for the right upper first permanent molar in females was the best (AGE = 74.96−1.427X−0.04X² + 0.001X³), with a mean absolute error (MAE) of 4.95 years. Conclusion In the process of age estimation, the volume of the first permanent molar pulp chamber has been proven to be an effective indicator. To improve the accuracy of age estimation, we recommend using models specific to gender and tooth type.
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View
Test of the auricular surface sex estimation method in fetuses and non-adults under 5 years old from the Lisbon and Granada Reference Collections
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Fetal age at death estimation on dry bone: Testing the applicability of equations developed on a radiographic sample
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The paucity of identified skeletal collections that include fetuses entails the need to pursue unconventional ap-proaches and resources in order to investigate fetal anatomi-cal variation. Radiographic analyses are being considered as a good alternative to data obtained in osteological collections. In a previous work, we developed equations to estimate gestation-al age (GA) at death by measuring fetal long bones on x-rays. This study aims to test the applicability of these equations in dry bones, and to assess its accuracy and bias. A test sample of 17 fetuses with known gestational age at death from the osteological collection of the Department of Legal Medicine, Toxi-cology and Physical Anthropology, Faculty of Medicine of the University of Granada (Spain) was employed. Examined bones comprised the femur, tibia, humerus and radius. The proposed models show high accuracy and low bias in the assessment of gestational age at death in a sample of fetal dry bones. The new equations, especially those obtained with classical calibration, are a valuable tool to estimate fetal gestational age at death in both forensic and archeological contexts.
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Age Estimation in Forensic Anthropology: methodological considerations about the validation studies of prediction models
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There is currently no clear consensus on how to calculate, express, and interpret the error when validating methods for age estimation in forensic anthropology. For this reason, it is likely that researchers are commonly drawing erroneous or confusing conclusions about the existence of population differences or the need to design new and increasingly complex estimation methods. In recent years, many researchers have highlighted these limitations. They propose new lines of research focused on the use of rigorous statistics and new technologies for the development of methods for estimating age. Our main objective in this study is to contribute to the strengthening of these novel ideas, for which we show the existing empirical evidence about the inadequacy of some age estimation methods in calculating, expressing, and interpreting the errors obtained. With this aim, a total of 500 simulations have been performed, in which hypothetical research teams develop and validate methods for age estimation. The data employed in this study was obtained from the “Centers for Disease Control and Prevention (CDC) Growth Charts: United States” released in 2000. The charts relate age with height, weight, and head circumference of US male children. Five learning algorithms have been employed as age estimators. We have performed three experiments in which the following aspects have been analyzed: frequency with which “negative” results can be obtained in the validation studies; which are the most appropriate criteria to compare and select the age estimation methods; and what analysis should be employed to carry out the validation studies. The results show possible errors in the interpretation of validation studies as a consequence of the confusion of statistical concepts. To conclude, we made a proposal of “good practices” for the correct calculation, expression, and interpretation of the error when validating age estimation methods in forensic anthropology.
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Age estimation is one of the crucial first steps in the identification of human skeletal remains in both forensic and archaeological contexts. In the postnatal period, age is traditionally estimated from dental development or skeletal growth, typically long bone diaphyseal length. However, in many occasions other methods are required. This study provides alternative means of estimating age of juvenile remains from the size of several cranial bones and the mandible. A sample of 185 identified juvenile skeletons between birth and 13 years of age from two European collections were used (Lisbon and Spitalfields). Measurements of the frontal, occipital-lateralis, occipital-basilaris, occipital-squamous, zygomatic, maxilla, and mandible were used to calculate classical calibration regression formulae for the sexes combined. The sample was divided into three age groups birth to 2 years, 2 to 6 years, and 2 to 12.9 years, depending on bone and its growth trajectory. For all the bones, measurements of the youngest age groups yielded the most precise age estimates. The vault bones on average yielded the best performing models, with the frontal bone having the most precise of all. The mandible performed on par with the best performing cranial bones, particularly in individuals under the age of 2 years. This study provides one of the most comprehensive approaches to juvenile age estimation based on bones of the skull, providing a resource that potentially can help estimate age of juvenile skeletons from a variety of circumstances.
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A critical review of sub-adult age estimation in biological anthropology: Do methods comply with published recommendations?
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The diversity of approaches and the high number of publications on sub-adult age estimation is a testament to the relevance of this particular area of forensic anthropological research. However, a downside of this diversity is the many methodological, sampling and statistical discrepancies between publications, which can lead to difficulties in method definition, application and comparison. Several authors have published recommendations highlighting standardized methodological parameters that should be respected and clearly appear in the original publications for anthropological methods to be valid. This study aims to objectively evaluate a corpus of 269 publications on dental and skeletal postnatal sub-adult age estimation using these recommendations translated into descriptors. These descriptors cover five sampling and five statistical parameters that can be considered valid or invalid according to published methodological recommendations. Parameter and descriptor distributions are shown in frequency tables and graphs, illustrating the general invalidity of the sampling and/or statistical protocols. Provided our corpus of methods is an accurate representation of available publications, the extrapolation of these results leads to conclude that most sub-adult age estimates are at worst invalid, at best questionable, and almost certainly method-dependent. In view of this study, rigorous and standardized sampling and statistical approaches should be preferred when applying and building sub-adult age estimation methods.
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Age estimation of immature human skeletal remains from the dimensions of the girdle bones in the postnatal period
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  • May 2017
Objectives: This study provides classical calibration regression formulae for age estimation from the dimensions of unfused shoulder and pelvic girdle bones. Materials and methods: Age estimation models were derived from a sample of 160 known age and sex individuals (63 females and 97 males) aged birth to 12 years, selected from Portuguese and English skeletal collections. The sample was divided into two age groups at the age of 2 years, and formulae were obtained for the sexes separately and combined. Results: Measurements of the pelvis provide more precise age estimates than the shoulder. In the younger age group, the height and width of the ilium, and the height of the glenoid yield the most precise age estimates. In the older age group, the length of the clavicle provides the most precise estimates, followed by measurements of the pubis and ischium. Discussion: In the younger individuals (<2 years), age estimates based on measurements of the pelvic girdle seem to be as or more precise than those based on the length of long bones. In older individuals (≥2 years), estimates based on the measurements of the girdles are less precise than those based on the length of long bones. These age estimation formulae may be useful for fragmentary and incomplete material in archaeological and forensic contexts. The formulae are suitable for a variety of archeological populations living under adverse conditions. These conditions are similar to some "developing" countries, and hence the formulae may also be applicable to modern forensic remains from such environments.
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