“This talk will focus on how humans acquired bipedalism via changes in the development of their pelves. At the crux of human bipedalism and childbirth is the ilium, which evolved to be shorter, broader, and parasagittally curved, compared to cranio-caudally tall, coronally-oriented ilia of other apes. The evolutionary genetic mechanisms that generated this unique iliac form remain unknown. Here, using histological, morphological, comparative genomic and functional genomic approaches on ethically collected human samples and museum-collected prenatal primates, we reveal that underlying this human iliac shape are two key developmental shifts. First, the human iliac growth plate underwent a spatial shift in orientation, residing perpendicular to that present in all other primate and mouse ilia. Using molecular methods, we discovered human accelerated sequence changes in numerous molecular pathways, permitting undifferentiated iliac skeletal cells to shift the direction of their outgrowth. Second, the human ilium experienced a timing shift in bone ossification unlike that observed for human long-bones, or in non-human primate ilia and long-bones. Human iliac ossification initiates at the posterior border, then radiates anteriorly, but remains external with external cells contributing initially to the production of bone. Compared to chimpanzees and other primates, humans delayed internal ossification of the ilium compared to other long bones. Underlying this shift are regulatory changes in other molecular pathways. The consequence of these shifts is a human pelvis that can grow, permit proper muscle orientation and function, all-the-while retaining its complex unique human shape for walking and birthing functions later in life.”

Terence D. Capellini is a Professor of Human Evolutionary Biology at Harvard University. His undergraduate education was at Binghamton University, where he was an Anthropology major focusing on human skeleton evolution. This was followed by his Masters Degree research at Kent State University, where he studied archaeological assemblage formation, and human skeletal evolution. He acquired his MPhil and Ph.D from the New York Consortium in Evolutionary Primatology (C.U.N.Y) working in the laboratory of Licia Selleri (Weill Cornell Medicine) on the development of the skeleton, and then performed his post-doctoral research in the laboratory of David Kingsley (Stanford University) on the genetics of skeletal evolution. His interdisciplinary lab at Harvard bridges functional genomics and genetics, developmental biology, medical genetics, and paleoanthropology. His lab is currently focusing on how gene regulation shapes different bones of the human skeleton, how interbreeding with Neandertals facilitated human skeletal adaptations, and how alterations to gene regulation during human evolution have not only facilitated skeletal adaptations but influenced the modern world-wide risk of bone diseases, such as joint-specific osteoarthritis.