Technical Note: Using Machine Learning to Predict Locomotor Behavior in Great Apes and Humans From Femur Metaphyseal Shape.

Objectives: The morphology of the hominoid distal femoral metaphyseal surface has been demonstrated to reflect locomotor behavior throughout ontogeny. Here, we quantify metaphyseal surface morphology to evaluate its predictive relationship to locomotor behavioral modes in hominoids.

Materials And Methods: We collected three-dimensional (3D) surface laser scans of the femora of 177 human and great ape individuals representing all subadult stages of development.

Predicting the Position of Hip Bones Within the Pelvic Girdle: A Case Study of the Kebara 2 Neanderthal.

Objectives: Poor preservation of hominin pelvises and the lack of soft tissue in the fossil record inhibits researchers' abilities to ascertain the true geometry of hominin pelvic girdles. The reconstruction process becomes subjective, largely relying on researchers' anatomical expertise, particularly, when the sacrum is absent or cannot be used to orient the hip bones. The bilateral symmetry of the pelvis, however, offers an opportunity to use one side to reconstruct potentially missing data on the other side.

A Macaque Model for the Effects of Hybridization on Body Size.

Objectives: Genomics research has uncovered recurrent hybridization between hominin species, yet its morphological impact remains understudied. Non-human primate research has suggested a morphological signature of hybrid ancestry, which could be used to identify hybrids in the hominin fossil record. This pattern may include extreme size, heightened variation, and markers of developmental instability, but factors affecting these characteristics are poorly understood.

Improving GWAS performance in underrepresented groups by appropriate modeling of genetics, environment, and sociocultural factors.

Genome-wide association studies (GWAS) and polygenic score (PGS) development are typically constrained by the data available in biobank repositories in which European cohorts are vastly overrepresented. Here, we increase the utility of non-European participant data within the UK Biobank (UKB) by characterizing the genetic affinities of UKB participants who self-identify as Bangladeshi, Indian, Pakistani, "White and Asian" (WA), and "Any Other Asian" (AOA), towards creating a more robust South Asian sample size for future genetic analyses. We assess the relationships between genetic structure and self-selected ethnic identities resulting in consistent patterns of clustering used to train a support vector machine (SVM).

A weakly structured stem for human origins in Africa.

Despite broad agreement that Homo sapiens originated in Africa, considerable uncertainty surrounds specific models of divergence and migration across the continent. Progress is hampered by a shortage of fossil and genomic data, as well as variability in previous estimates of divergence times. Here we seek to discriminate among such models by considering linkage disequilibrium and diversity-based statistics, optimized for rapid, complex demographic inference.

Developing an automated skeletal phenotyping pipeline to leverage biobank-level medical imaging databases.

Objectives: Collecting skeletal measurements from medical imaging databases remains a tedious task, limiting the research utility of biobank-level data. Here we present an automated phenotyping pipeline for obtaining skeletal measurements from DXA scans and compare its performance to manually collected measurements.

Materials And Methods: A pipeline that extends the Advanced Normalization Tools (ANTs) framework was developed on 341 whole-body DXA scans of UK Biobank South Asian participants.

Predicting the shape, size, and placement of adult human pubic symphyses.

Objectives: When reconstructing fossil pelves, the articulation of the pelvic bones largely relies on subjective decisions by researchers. Different positionings at the pubic symphysis can affect the overall morphology of the pelvis and the subsequent biological interpretation associated with that individual or species. This study aims to reduce this subjectivity using quantitative models to predict pubic symphysis morphology.

Effects of hybridization on pelvic morphology: A macaque model.

Ancient DNA analyses have shown that interbreeding between hominin taxa occurred multiple times. Although admixture is often reflected in skeletal phenotype, the relationship between the two remains poorly understood, hampering interpretation of the hominin fossil record. Direct study of this relationship is often impossible due to the paucity of hominin fossils and difficulties retrieving ancient genetic material.

Inferring archaic introgression from hominin genetic data.

Questions surrounding the timing, extent, and evolutionary consequences of archaic admixture into human populations have a long history in evolutionary anthropology. More recently, advances in human genetics, particularly in the field of ancient DNA, have shed new light on the question of whether or not Homo sapiens interbred with other hominin groups. By the late 1990s, published genetic work had largely concluded that archaic groups made no lasting genetic contribution to modern humans; less than a decade later, this conclusion was reversed following the successful DNA sequencing of an ancient Neanderthal.

Virtual reconstruction of the Kebara 2 Neanderthal pelvis.

The paucity of well-preserved pelvises in the hominin fossil record has hindered robust analyses of shifts in critical biological processes throughout human evolution. The Kebara 2 pelvis remains one of the best preserved hominin pelvises, providing a rare opportunity to assess Neanderthal pelvic morphology and function. Here, we present two new reconstructions of the Kebara 2 pelvis created from CT scans of the right hip bone and sacrum.

Ontogeny of the distal femoral metaphyseal surface and its relationship to locomotor behavior in hominoids.

Objective: Distal femoral metaphyseal surface morphology is highly variable in extant mammals. This variation has previously been linked to differences in locomotor behavior. We perform the first systematic survey and description of the development of this morphology in extant hominoids.

Clarifying distinct models of modern human origins in Africa.

Accumulating genomic, fossil and archaeological data from Africa have led to a renewed interest in models of modern human origins. However, such discussions are often discipline-specific, with limited integration of evidence across the different fields. Further, geneticists typically require explicit specification of parameters to test competing demographic models, but these have been poorly outlined for some scenarios.

Using geometric morphometric visualizations of directional selection gradients to investigate morphological differentiation.

Researchers studying extant and extinct taxa are often interested in identifying the evolutionary processes that have lead to the morphological differences among the taxa. Ideally, one could distinguish the influences of neutral evolutionary processes (genetic drift, mutation) from natural selection, and in situations for which selection is implicated, identify the targets of selection. The directional selection gradient is an effective tool for investigating evolutionary process, because it can relate form (size and shape) differences between taxa to the variation and covariation found within taxa.

Changes in human skull morphology across the agricultural transition are consistent with softer diets in preindustrial farming groups.

Agricultural foods and technologies are thought to have eased the mechanical demands of diet-how often or how hard one had to chew-in human populations worldwide. Some evidence suggests correspondingly worldwide changes in skull shape and form across the agricultural transition, although these changes have proved difficult to characterize at a global scale. Here, adapting a quantitative genetics mixed model for complex phenotypes, we quantify the influence of diet on global human skull shape and form.

Estimators for Q and coalescence times.

Comparisons of to can provide insights into the evolutionary processes that lead to differentiation, or lack thereof, among the phenotypes of different groups (e.g., populations, species), and these comparisons have been performed on a variety of taxa, including humans.

Neonatal postcrania from Mezmaiskaya, Russia, and Le Moustier, France, and the development of Neandertal body form.

Neandertal and modern human adults differ in skeletal features of the cranium and postcranium, and it is clear that many of the cranial differences-although not all of them-are already present at the time of birth. We know less, however, about the developmental origins of the postcranial differences. Here, we address this deficiency with morphometric analyses of the postcrania of the two most complete Neandertal neonates-Mezmaiskaya 1 (from Russia) and Le Moustier 2 (from France)-and a recent human sample.

Comparative perspective on antemortem tooth loss in Neandertals.

Neandertal specimens with severe antemortem (before death) tooth loss (AMTL) are sometimes interpreted as evidence for human-like behaviors in Neandertals, such as conspecific care or cooking, although it is uncertain whether AMTL frequencies in Neandertals are similar to those in modern humans and exceed those in non-human primates. This study characterizes AMTL (all tooth types) in Neandertals relative to recent human hunter-gatherers and several non-human primate taxa using binomial-normal regression models fit in a Bayesian framework to a sample of 25 Neandertals, 310 recent human hunter-gatherers, 61 chimpanzees, 38 orangutans, and 75 baboons. The probability that a tooth is lost antemortem is modeled to depend on tooth class, taxon, and estimated age at death.

A mixed model for the relationship between climate and human cranial form.

Objectives: We expand upon a multivariate mixed model from quantitative genetics in order to estimate the magnitude of climate effects in a global sample of recent human crania. In humans, genetic distances are correlated with distances based on cranial form, suggesting that population structure influences both genetic and quantitative trait variation. Studies controlling for this structure have demonstrated significant underlying associations of cranial distances with ecological distances derived from climate variables.

Unconstrained cranial evolution in Neandertals and modern humans compared to common chimpanzees.

A variety of lines of evidence support the idea that neutral evolutionary processes (genetic drift, mutation) have been important in generating cranial differences between Neandertals and modern humans. But how do Neandertals and modern humans compare with other species? And how do these comparisons illuminate the evolutionary processes underlying cranial diversification? To address these questions, we used 27 standard cranial measurements collected on 2524 recent modern humans, 20 Neandertals and 237 common chimpanzees to estimate split times between Neandertals and modern humans, and between Pan troglodytes verus and two other subspecies of common chimpanzee. Consistent with a neutral divergence, the Neandertal versus modern human split-time estimates based on cranial measurements are similar to those based on DNA sequences.

Variation and signatures of selection on the human face.

There has been much debate about why humans throughout the world differ in facial form. Previous studies of human skull morphology found levels of among-population differentiation that were comparable to those of neutral genetic markers, suggesting that genetic drift (neutral processes) played an important role in influencing facial differentiation. However, variation in soft-tissue morphology has not been studied in detail.

Brief Communication: Quantitative- and molecular-genetic differentiation in humans and chimpanzees: implications for the evolutionary processes underlying cranial diversification.

Estimates of the amount of genetic differentiation in humans among major geographic regions (e.g., Eastern Asia vs.

Did a discrete event 200,000-100,000 years ago produce modern humans?

Scenarios for modern human origins are often predicated on the assumption that modern humans arose 200,000-100,000 years ago in Africa. This assumption implies that something 'special' happened at this point in time in Africa, such as the speciation that produced Homo sapiens, a severe bottleneck in human population size, or a combination of the two. The common thread is that after the divergence of the modern human and Neandertal evolutionary lineages ∼400,000 years ago, there was another discrete event near in time to the Middle-Late Pleistocene boundary that produced modern humans.

Do modern humans and Neandertals have different patterns of cranial integration?

Studies of cranial differences between modern humans and Neandertals have identified several characteristics for which the two groups differ in their mean values, the proportional relationships with other traits, or both. However, the limited number of fairly complete Neandertals has hindered investigations into patterns of integration - covariance and correlation among traits - in this fossil group. Here, we use multiple approaches specifically designed to deal with fragmentary fossils to test if metric cranial traits in Neandertals fit modern human patterns of integration.