The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Evolvability and integration in human and non-human primate limbs


Department of Anthropology, University of Tennessee Knoxville

Friday 1:45-2:00, 200ABC Add to calendar

Limb length proportions (LPs) in humans and other primates are widely assumed to be highly genetically controlled traits that change only in response to long-term selection. For instance, the global pattern of variation in human LPs correlates with latitudinal variation in the Old World, a pattern explained as a specialized adaptation that developed over hundreds of thousands of years for the efficient regulation of heat loss. The clinal differences seen in modern human LPs are therefore largely due to genetic variance among groups; however, the way in which this genetic variance evolved is unclear. A better understanding of the genetic variation and integration of these complex traits is needed to fully understand the modern pattern of human phenotypic variation.

Using four large, pedigreed primate samples (tamarins, two samples of baboons, and humans), this project seeks to explore the 1) evolvability, or the expected proportional change in a trait per unit of a mean-standardized selection gradient, and 2) integration, or covariation, of primate limb segments. Non-human primate samples were used as models for humans and to see if patterns of variation and integration are consistent across primates. Preliminary results indicate that while evolvabilities of limb segments are comparable across species, patterns of integration in some samples do not follow previously reported patterns. These results show that phenotypic variance alone cannot predict how limb elements will respond to selection pressures. Furthermore, these results will help model expected change in LPs, which may then be compared with observed clinal patterns reported among humans.

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