New Study Sheds Light on Early Human Hair Evolution – UMass News and Media Relations

Among primates, including humans, hair is an important feature of diversity and evolution, serving functions tied to thermoregulation, protection, camouflage and signaling. However, the evolution of wild primate hair has remained relatively understudied until recently.

Now, University of Massachusetts evolutionary anthropologist Jason Kamilar and researchers from thePrimate Genomics Lab at the George Washington Universityhave examined what factors drive hair variation in a family of wild lemur populations known as Indriidae.

In a new study published in the American Journal of Biological Anthropology, the researchers specifically aimed to assess the impacts of climate, body size and color vision on hair evolution.

They found:

The reduced body hair that modern humans exhibit is unique among primates, says Kamilar, an associate professor of anthropology at UMass Amherst. Unfortunately, hair does not fossilize, so studying how human hair has evolved through time is very challenging, although we can study our primate relatives to give us insight into our deep-time ancestors.

Brenda Bradley, an associate professor of anthropology who directs GWs Primate Genomics Lab and is a co-author on the study, explains that our understanding of hair evolution and diversity in other primates helps us fill in the gaps of our own human evolutionary story.

Most people are intrigued by the diversity of hair on their own bodies, and the variety of hair types among people around the world, Bradley said. Understanding hair patterns in non-human primates, such as these lemurs, may provide a comparative context for understanding how variation arose in human hair.

We examined lemurs in Madagascar that live in a variety of habitats, but consistently exhibit an upright posture similar to human ancestors, and found that lemurs living in hot, dry environments had higher hair follicle density on the top of their head, Kamilar says. This may be related to greater UV exposure for this part of their body, which has been a hypothesis proposed to explain the presence of high human head hair density.

The researchers note future work should focus on samples across smaller geographic or phylogenetic (family-level, genus-level) scales and from diverse non-human and human populations.

The complete study, Hair phenotype diversity across Indriidae lemurs, is now available online from the American Journal of Biological Anthropology.

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New Study Sheds Light on Early Human Hair Evolution - UMass News and Media Relations