Fossil Record
Paleoanthropologists at UC Davis are broadly interested in using the fossil record to understand human evolution. This research is currently being guided by specific research questions.
What is the meaning of Neandertal skeletal morphology? Neandertals and humans shared a recent common ancestor are similar in many ways, but there differences between the skeletons of these two groups. These differences could have been shaped across multiple generations by evolutionary processes such as genetic drift or natural selection, or they may be the result of the environmental stimuli experienced by individuals during their lifetimes. Members of Prof. Weaver’s lab address this question in a variety of ways. They use theory from evolutionary qualitative genetics to determine the relative roles of genetic drift and natural selection in producing cranial differences between Neandertals and humans. They use virtual reconstruction methods to investigate childbirth and the evolution of the pelvis in Neandertals. They study non-adult Neandertals to determine which adult Neandertal characteristics are present early in growth and development.
How did hybridization in human evolution affect skeletal morphology? After the origins of Homo sapiens in Africa, some humans spread into Eurasia, where they encountered and exchanged genes with Neandertals and Denisovans. The genomic consequences of these interactions have been extensively investigated, but much less known about how they affected morphology. Members of Prof. Weaver’s lab are studying the genome and skeletal morphology of a colony of crosses between Indian and Chinese rhesus macaques as a model for hybridization in human evolution (see also Extant Humans & Primates tab).
How did early hominins move around their environments? Members of Prof. Weaver’s lab address this question by studying aspects of the skeleton that provide information about locomotor behavior in humans and extant non-human primates and use this information to make inferences about the locomotor behavior of early hominins.
How do evolutionary processes shape craniofacial morphology in Plio-Pleistocene hominins? Members of Prof. Jung’s lab investigate how evolutionary processes have shaped craniofacial morphology in Plio-Pleistocene hominins. Using evolutionary quantitative genetics methods and skull measurements that are informative about feeding biomechanics, this research tests competing evolutionary models and evaluates adaptive hypotheses concerning hominin craniofacial evolution. By distinguishing patterns expected under directional selection from those consistent with neutral evolutionary processes, this research aims to elucidate the evolutionary mechanisms underlying craniofacial morphological diversity in Plio-Pleistocene hominins.
How does the morphology of the last common ancestor influence the evolutionary pathways of the early hominin skeleton? There is an ongoing debate in paleoanthropology over whether the last common ancestor (LCA) of humans and chimpanzees was more similar to extant apes or monkeys, largely because of the sparse fossil record around the time of the divergence of the two lineages. This debate is important because interpretations of how the skeletal morphologies of early hominins evolved from the LCA depend on the morphological characteristics attributed to the ancestor—for example, whether it possessed a more great ape-like or more large-bodied monkey-like morphology. For instance, estimates of the number of evolutionary reversals and steps required to evolve from the LCA to hominins, including modern humans, depend on the inferred ancestral state; a great ape-like LCA, for example, would imply more evolutionary reversals in the evolution of human lower-back morphology. Members of Prof. Jung’s lab seek to advance this debate by investigating skeletal morphological evolution through an integrative framework that combines the fossil record of hominoids and early hominins with evolutionary quantitative genetics, phylogenetic comparative methods, feeding and locomotor biomechanics, and computer simulations.