The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


Developing the brain: A potential role for the placenta in hominin brain evolution

JULIENNE N. RUTHERFORD1,2,3, ELIZABETH T. ABRAMS3 and SANA J. SAID3.

1Department of Oral Biology, University of Chicago at Illinois, 2Comparative Primate Biology Laboratory, University of Chicago at Illinois, 3Department of Anthropology, University of Chicago at Illinois

Friday 4:45-5:00, Galleria North Add to calendar

Of all primates, humans produce the largest, fattest, most encephalized neonates, relative to maternal size. Possessing this unique suite of characteristics at birth suggests that the intrauterine supply of nutrients available to the developing fetus has increased or been made more efficiently available in hominids compared to other primates. We discuss three interrelated phenomena to explain how the prenatal environment changed for the hominins and how these changes created the required nutritional reservoir to grow big-brained babies, forming the developmental foundation for the encephalization that is the hallmark of human evolution. First, we examine postulated changes in body size and diet in the hominin lineage that changed gestational energetics. Next, we address the impact that significant locomotor changes might have had on gestation. This leads to a discussion of the role the placenta plays in supplying the fetus (and the fetal brain) with maternally derived nutrients and how changes in hominin placentation might have been a key underpinning of increases in brain size. We posit that the schema of hominin placentation coupled with dietary changes increased the intrauterine transport of nutrients and was necessary to build the developmental foundation for significant increases in brain mass during the last two million years of human evolution.

Funding was provided by Wenner-Gren (Abrams) and a Building Interdisciplinary Research Careers in Women’s Health (BIRCWH) faculty scholarship (Rutherford) from the National Institute of Child Health and Human Development and the National Institutes of Health Office of Research on Women’s Health (K12HD055892).

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