Figure 2 - uploaded by Kate McGrath
Content may be subject to copyright.
Perikymata and linear hypoplastic defect depths by tooth type. Neanderthals have significantly shallower perikymata (n = 280; 150 H. sapiens and 130 Neanderthal) and defects (n = 71; 35 H. sapiens and 36 Neanderthal) than H. sapiens. Inter-and intra-individual comparisons suggest that faster-growing and thinnerenameled teeth (i.e., Neanderthals compared to H. sapiens; incisors compared to canines) have shallower perikymata and defects at the population level. LLI1/ULI1 = lower/upper central incisor; LLI2/ULI2 = lower/ upper lateral incisor; LC = lower/upper canine. Figure generated in RStudio (version 1.3.959) 50 .
Source publication
Early life stress disrupts growth and creates horizontal grooves on the tooth surface in humans and other mammals, yet there is no consensus for their quantitative analysis. Linear defects are considered to be nonspecific stress indicators, but evidence suggests that intermittent, severe stressors create deeper defects than chronic, low-level stres...
Contexts in source publication
Context 1
... Neanderthal sample has significantly shallower perikymata than the H. sapiens sample (F(1,12) = 27.8, p < 0.001) (Fig. 2). The H. sapiens sample has perikymata that are an average of 2.33 times (range 1.69-3.65) deeper than the Neanderthal sample in incisors, and 3.24 times (range 3.05-3.65) deeper in canines. Perikymata depths range from shallowest in the La Chaise Neanderthal upper canines and incisors to the deepest in the Çatalhöyük lower canines and ...
Context 2
... Neanderthal sample also has significantly shallower LEH defects than H. sapiens (F(1,16) = 30.0, p < 0.001) (Fig. 2). Defect depths follow a similar pattern with La Chaise Neanderthal upper incisors having the shallowest defects and H. sapiens lower canines from the Saxon burials at Hildesheim and Çatalhöyük having the deepest defects. However, there are no significant differences in LEH severity ratios between Neanderthals and H. sapiens, as ...
Context 3
... ( To test the effect of leveling algorithms that have been used in other studies to remove the effect of curvature 15,20 , and ultimately move toward a methodological consensus for measuring defect depth, plane and sphere-type form removal algorithms (within SensoSCAN) were applied to two digital elevation models (DEMs) from Le Moustier canines (Fig. S2). Leveled values underestimate the depth of defects, being on average 24.3% shallower than raw depths (range = 16.1-27.9%; N = 4), and with a mean absolute difference of 9.9 µm (range = 6.9-11.1 µm; N = 4). When the same algorithms are applied to perikymata, they have the opposite effect, making perikymata appear artificially deeper. ...
Context 4
... to earlier hominins Australopithecus africanus (26.0 µm) and H. naledi (26.9 µm) as reported by Skinner 21 , as well as nonhuman apes (23.6 µm in mountain gorillas). However, the A. africanus and H. naledi depths 21 were collected from leveled DEMs and therefore likely underestimate the true depth, based on our comparisons of leveled vs. raw data (Fig. S2). In terms of differences among the H. sapiens samples, relatively little is known about enamel growth variation within our species. A histological analysis of contemporary European and South Africans 37 , and the variation in the timing of dental eruption 38 , suggest that considerable variation can be expected. ...
Similar publications
Denisova Cave in southern Siberia is the type locality of the Denisovans, an archaic hominin group who were related to Neanderthals1–4. The dozen hominin remains recovered from the deposits also include Neanderthals5,6 and the child of a Neanderthal and a Denisovan7, which suggests that Denisova Cave was a contact zone between these archaic hominin...
Citations
... However, that study did not adequately control for enamel surface abrasion, which can wear away minor defects, and relied on observations made with a 10× hand lens. Newer protocols for LEH observation emphasize the exclusion of teeth with abraded enamel surfaces and utilize improved imaging techniques (e.g., Guatelli-Steinberg, Ferrell, and Spence 2012;McGrath et al. 2018McGrath et al. , 2021. These methodological advances make it worthwhile to reexamine the transfer question. ...
... Depending upon where measurements were taken in relation to perikymata, the most minor defects are likely to have been missed, but the threshold for detection is the same overall enamel surfaces examined. McGrath et al. (2021) used a confocal profilometer to measure defect depth factoring out underlying surface curvature. Measurements of defect depths were not analyzed here as the measuring microscope's software (VisionGauge; Visionx ...
Linear enamel hypoplasias (LEHs) are development defects appearing as lines or grooves on enamel surfaces. Forming when physiological stressors disrupt developing teeth, LEHs provide retrospective insight into stress experienced in early development. Here, LEHs in Cayo Santiago rhesus macaques ( Macaca mulatta ) were observed with respect to decade of birth, whether an individual was transferred from the free‐ranging colony to the captive facility during probable crown formation periods, and matriline of birth. It was hypothesized that later decades would exhibit higher prevalence than earlier decades as climatic conditions in Puerto Rico worsened over time. Transfer was expected to affect LEH formation because the process of transfer, and subsequent restriction to captivity, is thought to be stressful. Matriline membership was hypothesized to relate to LEH formation because there is some evidence of a genetic influence on susceptibility to form LEH and because offspring of matrilines of different dominance ranks are known to experience different levels of aggression. Lower third premolars with minimal enamel surface wear were scored for LEH using a digital microscope, while a follow‐up analysis of the two matrilines with the most extreme differences in LEH frequency was conducted using enamel surface profiles. Results were: (1) individuals born during the 1990s had significantly greater LEH prevalence than those born in the 1960s, (2) transferred individuals exhibited weak evidence of greater LEH prevalence than nontransferred comparison groups, and (3) matrilines did not differ in LEH expression in the initial or follow‐up analysis. Although sample sizes were small for some comparisons, these results suggest that not all decades saw an equal prevalence of LEH, that there might be a small effect of transfer from free‐ranging to captive conditions on LEH prevalence that is difficult to detect, and that the matriline into which an individual is born is not related to LEH expression.
... Modern scientific and commercial technological advancements necessitate nanometer-resolution surface topography over a broad dynamic range. With the growing demand for miniaturized devices such as nano/micro electromechanical systems (NEMS and MEMS) [1,2], nanostructured optical interfaces [3], and micro-fluidic chips [4], economical and convenient two and three-dimensional surface profilometry has gained popularity, allowing for roughness estimation [5], morphological analysis [6,7] film thickness measurement [8,9] and structural assessment of integrated devices [10,11]. Electrical profilometry maps micron-sized surface characteristics using sensitive impedance-based probing methods [12,13], whose performance is substrate dependent and incurs non-linearity. ...
Surface characterization is essential for a technical evaluation of device performance and to assess surface dynamics in fabrication units. In this regard, a number of surface profiling techniques have been developed that accurately map sample topography but have significantly limited detection range. Here, we demonstrate a cascaded non-contact fiber interferometer-based approach for real-time high-precision surface profiling with ultrawide detection range (nm to mm). This compact interferometers’ system operates by wavelength interrogation that provides a scope to study several types of surfaces and has a tunable cavity configuration for varying the sensitivity and range of the detectable features’ size. The proposed system enables nanoscale profiling over 10–1000 nm with resolution of 10 nm and microscale mapping over 1–1000 µm with resolution of 0.2 µm. The technique is utilized to map the features of nanostructured surfaces and estimate the surface roughness of standardized industrial samples.
... Given the vast etiology of dental enamel hypoplasia and the variability of potential stressors 11,13,[18][19][20][21] , we follow here Temple and Goodman 22 , in using the term "developmental or childhood stress" to describe a physiological disruption sufficient to affect hard tissue formation. The potential of using enamel growth disruptions, particularly in their linear form (LEH), to elucidate stress profiles of past populations has prompted many studies to track enamel hypoplasia occurrences in Paleolithic hominins 10,[23][24][25][26][27][28][29][30][31] . However, these have provided contradictory results when it comes to reconstructions and comparisons of stress levels in Neanderthals and UPMH. ...
... They reveal that the probability for any single tooth to manifest a hypoplastic defect (of any form) is similar in Neanderthals and UPMH. These results support previous work arguing for the lack of substantial differences in overall childhood stress levels between the two hominin groups [8][9][10] . Our findings therefore counter arguments that Neanderthal lives were generally much more stressful compared to those of UPMH. ...
Neanderthals’ lives were historically portrayed as highly stressful, shaped by constant pressures to survive in harsh ecological conditions, thus potentially contributing to their extinction. Recent work has challenged this interpretation, leaving the issue of stress among Paleolithic populations highly contested and warranting in-depth examination. Here, we analyze the frequency of dental enamel hypoplasia, a growth disruption indicator of early life stress, in the largest sample of Neanderthal and Upper Paleolithic dentitions investigated to date for these features. To track potential species-specific patterns in the ontogenetic distribution of childhood stress, we present the first comprehensive Bayesian modelling of the likelihood of occurrence of individual and matched enamel growth disruptions throughout ontogeny. Our findings support similar overall stress levels in both groups but reveal species-specific patterns in its ontogenetic distribution. While Neanderthal children faced increasing likelihoods of growth disruptions starting with the weaning process and culminating in intensity post-weaning, growth disruptions in Upper Paleolithic children were found to be limited around the period of weaning and substantially dropping after its expected completion. These results might, at least in part, reflect differences in childcare or other behavioral strategies between the two taxa, including those that were advantageous for modern humans’ long-term survival.
... Their behavioral repertoire was thought to have provided UPMH with a competitive advantage over Neanderthals, allowing them to persist while Neanderthals perished [3][4][5][6][7][8][9]. Some recent studies, however, are casting doubt on this view, arguing instead that Neanderthals and UPMH led similarly stressful lives [10][11][12]. ...
... Thus, enamel hypoplasia, especially in its linear form (LEH), is considered a well-established marker of non-speci c physiological stress experienced during ontogeny [13][14][15]23]. The potential of using enamel growth disruptions to elucidate stress pro les of past populations has prompted many studies to track enamel hypoplasia occurrences in Paleolithic hominins [12,[24][25][26][27][28][29][30][31][32]. However, these have provided contradictory results when it comes to reconstructions and comparisons of stress levels in Neanderthals and UPMH. ...
... They reveal that the probability for any single tooth to manifest a hypoplastic defect (of any form) is similar in Neanderthals and UPMH. These results support previous work arguing for the lack of substantial differences in overall childhood stress levels between the two hominin groups [12,20,21,35]. Our ndings therefore counter arguments that Neanderthal lives were generally much more stressful compared to those of UPMH. ...
Neanderthals’ lives historically portrayed as highly stressful, shaped by constant pressures to survive in harsh ecological conditions, thus potentially contributing to their extinction. Recent work has challenged this interpretation, leaving the issue of stress among Paleolithic populations highly contested and warranting in-depth examination.
Here, we analyze the frequency of dental enamel hypoplasia, a physiological stress induced pathology, in the largest sample of Neanderthal and Upper Paleolithic dentitions investigated to date. To track potential species-specific patterns in the ontogenetic distribution of childhood stress, we present the first comprehensive Bayesian modelling of the likelihood of occurrence of individual and matched enamel growth disruptions throughout ontogeny.
Our findings support similar overall stress levels in both groups but reveal species-specific patterns in its ontogenetic distribution. While Neanderthal children faced increasing stress starting with the weaning process and culminating in intensity post-weaning, physiological stress in Upper Paleolithic children was found to be limited to the period of weaning and substantially dropping right after its completion. These results might, at least in part, reflect differences in childcare or other behavioral strategies between the two taxa, including those that were advantageous for modern humans’ long-term survival.
... 179 188 and ultimately allowing us to better interpret these same features in individuals without associated records, like wild apes 121 and fossil hominins. 187 In piecing together two studies, 56,117 we see how the four recommendations can be put into action. Haloko's name was utilized and context described in both studies (Section 4.1), and between the long bone data and dental defect data, her body parts can be rearticulated to one story (Section 4.2). ...
... Based on what we know about collection practices at this time, it is not surprising that being taken from her mother, losing access to her usual food sources, and traveling by ship to another continent would have been a major stress event. Haloko gave birth to four live offspring as an adult, but the caretaking duties were transferred to other female gorillas, which might provide further evidence of the long-lasting impact of her traumatic early life experiences.Haloko's dental defect is the deepest and most pronounced of any measured in great apes, humans, and extinct hominins to date.63,187 Had we followed the usual protocol of removing "captive" individuals or outliers from the data set, and not sought out associated records about her life, we might have missed the opportunity to understand how major stressors can permanently leave their mark in the form of major enamel defects. ...
Extensive discourse surrounds the ethics of human skeletal research and curation, but there has yet to be a similar discussion of the treatment of great ape skeletal remains, despite the clear interest in their ethical treatment when alive. Here we trace the history of apes who were killed and collected for natural history museums during the early 20th century and showcase how the guiding research questions of the colonial era continue to influence scholarship. We discuss best practices for improving industry and academic standards of research on, and the curation of, ape remains. The suggested interventions involve restoring individual identity and narrative to great apes while engaging with contextual reflexivity and decolonial theory. The resulting recommendations include contextualizing the individual, piecing individuals back together, challenging/questioning the captive‐wild dichotomy, and collaborative international conversations. Our objective is to encourage a conversation regarding ethical and theoretical considerations in great ape skeletal remains research.
... One condition that has long served as a marker of metabolic or systemic perturbation in bioarchaeology and paleoanthropology is enamel hypoplasia. This work persists today, albeit with methodological advances and refined interpretive paradigms (e.g., Elcock et al., 2006;Ham et al., 2021;McGrath et al., 2021;Towle & Irish, 2020). ...
Genealogical samples that couple dental data and documented relatedness information provide unique opportunities to examine the biological foundations of tooth variation. Over the past century, these resources have been critical for examining the various factors that influence dental phenotypes—the same traits that anthropologists regularly apply to reconstructions of past phenomena. Genealogical samples are uniquely suited to test long‐standing assumptions underlying bioanthropological practice, for example, biodistance and phylogenetic analysis, which commonly reference aspects of tooth size and form as proxies for latent genetic information. This article provides an overview of published genealogical research, with a focus on the practical implications of quantitative genetic and environmental studies of (non)human primate dentitions. To highlight the utility of genealogical samples for understanding the influence of specific non‐genetic factors on dental characters, we also present novel data on gestational hormone effects in opposite‐sex dizygotic twin pairs as a test of the twin testosterone transfer (TTT) hypothesis. This article discusses fruitful next steps in genealogical dental research, as well as important ethical considerations surrounding the use of associated datasets, which are sensitive in nature. As we forge ahead in an age of phenomics, genealogical samples are likely to play a key role in generating comprehensive genotype–phenotype maps of the dentition and in refining bioanthropological methods.
... This is because defect margins are not always well-defined due to the curvature of the tooth and differences in perikymata widths within a defect (Hillson & Bond, 1997). Research using enamel depth profiles and/or micro-CT imaging may remedy the issue of subjective defect and duration identification (e.g., Cares Henriquez & Oxenham, 2020;McGrath et al., 2021;Xing et al., 2016). However, such methodology is associated with its own set of limitations because it requires specialized equipment that cannot usually be applied to larger bioarchaeological samples required for studies of FA, caused by restrictions from data collection and travel. ...
Objectives
Recent tests of the relationship between enamel defects, an indicator of early life stress, and fluctuating asymmetry (FA), a measure of cumulative developmental instability, have produced equivocal results. This may be because they use methods that underestimate the number of defects. We reinvestigate this relationship using high‐resolution microscopy images of tooth surfaces. Further, we test the hypothesis that developmental stresses during the earliest period of tooth development have a greater impact on FA than stresses during subsequent periods.
Materials and Methods
The sample consists of 48 individuals from two colonial‐era cemeteries in Mexico City. Using one canine from each individual, we created photomontages using a 2D light microscope. Tooth crowns were divided into three developmental periods. Defects were identified as widely spaced perikymata using moving z‐scores. We compared defect presence, frequency, and timing to FA calculated from 11 landmarks using geometric morphometrics from 3D models of each cranium.
Results
Both the presence and frequency of enamel defects are significantly associated with an increase in FA. Contrary to our expectations, defects that formed in the latest developmental period (4–5.5 years) were uniquely associated with an increase in FA, relative to the other two periods.
Discussion
The presence and frequency of stress during childhood increases developmental instability. The time between 4 and 5.5 years may be a sensitive window of development in which disruptions to growth have a long‐lasting effect on developmental instability. Results indicate that research on developmental stress should consider the timing and frequency of stress events to more fully understand their impact on later life.
... These disruptions can also interfere with the development of the endocrine system and the production of adult male sex hormones, potentially impacting reproduction (Bribiescas, 2001). However, since developmental stress, indicated most clearly by enamel hypoplasia (indicating systemic disease, infection, or severe lack of nutrition), is not more common in Neanderthals compared to archeological and contemporary foraging populations (McGrath et al., 2021;Trinkaus, 2018), it is unlikely to have affected their reproductive success. However, there is a clear link with hypoplasias and potential weaning age (fourth year) and adolescence (twelfth year) in the El Sidrón sample (Rosas et al., 2006). ...
Despite a remarkably persistent pop culture image of Neanderthals as semi-upright, hairy, cavemen wielding clubs, science provides us with a different picture. There is no doubt that the evolutionary forces that shaped Neanderthals and Homo sapiens differed, but recent evidence of interbreeding tells us that our anatomy and physiology were compatible and differences in physical appearance were not an obstacle to social interaction. Similarities in growth and development indicate that, like us, Neanderthals also gave birth to helpless young, and imply complex social lives necessary to support reproduction and protracted phases of offspring development. Of course, some uncertainty will always surround the behaviors of extinct species, but we can be sure that Neanderthals had sex and successfully reproduced for hundreds of thousands of years, and the archeological record and DNA evidence can illuminate behaviors that are invisible anatomically. In this chapter, we synthesize diverse data, theories, and models to reconsider aspects of Neanderthal sexual and reproductive behavior, and contextualize inferences within our current understanding of their physical characteristics, life-ways, and genomics.
... In particular, photogrammetry and confocal microscopy have been widely used to quantify alterations preserved at micro-and nano-scopic scales on the surface of materials. The applications of these techniques permit, for instance, (1) study of cut marks and taphonomic alterations on bone surfaces, (2) identification of the functional history of stone and bone tools and personal ornaments through use-wear analysis, (3) reconstruction of the diet and environment of past human and non-human animal groups through dental macro-and microwear analysis, and (4) elucidation of biological processes, such as growth and its disturbances through the study of growth increments in teeth and bones(Calandra et al., 2019;Galland et al., 2018;Li et al., 2020;Magnani et al., 2020;Maté-González et al., 2017;McGrath et al., 2021;Rosso et al., 2017;Schmidt et al., 2020;Stemp, 2014;Yravedra Sainz de los Terreros et al., 2019).Furthermore, other 3D techniques such as X-ray, synchrotron radiation, and neutron microtomography have been widely used to non-invasively study the internal structure of bones and teeth, which holds a significant amount of valuable information for providing taxonomic identification, reconstructing phylogenetic relationships, and assessing adaptive strategies in past groups (among others, see studies byBayle et al., 2010;Beaudet et al., 2016;Benazzi et al., 2011;Crevecoeur et al., 2014;Détroit et al., 2019; ...
Higher education in evolutionary anthropology involves providing students with in‐depth knowledge of biological and cultural heritage sites and collections that are frequently inaccessible. Indeed, most sites, fossils, and archaeological remains can be visited or manipulated only rarely and solely by specialists with extensive experience. Owing to the development of 3D and medical imaging techniques, this fragile heritage is now more widely accessible, and in a dynamic way. However, exclusive adoption of virtual teaching and learning has a negative impact on student engagement and, naturally, on exchanges with instructors, and thus cannot be used without some reservations. In the ITAP (Immersion dans les Terrains de l’Anthropologie biologique et de la Préhistoire) project of the higher education STEP (Soutien à la Transformation et à l’Expérimentation Pédagogiques) transformation program at the University of Bordeaux, we combine student‐active teaching with Master's students fully immersed in ongoing fieldwork, laboratory study, and dissemination of research results in order to develop more individually shaped learning curricula and to foster both professional and new interdisciplinary skills. Here, we present examples of experiments conducted in the ITAP project using both authentic and virtual collections of archaeological, experimental, and reference materials that help to break down the barriers between research activities and higher education, as well as providing a more general appraisal of the appropriate use of virtual tools in higher education by combining them with real‐life situations. The article describes examples of novel teaching methods that we have developed in our Master's program in evolutionary anthropology, where we combine student‐active teaching with Master's students fully immersed in ongoing fieldwork, laboratory study, and dissemination of research results.
... A short postnatal enamel formation period has been reported for a deciduous incisor of the Fumane 2 upper Palaeolithic modern human infant (39-42 ka) [29], which differs from longer enamel growth periods reported for extant humans [37]. Relatively rapid formation rates have also been reported for Neanderthal permanent anterior teeth [21,47]. ...
