New study sheds light on early human hair evolution

Date:
March 9, 2022
Source:
George Washington University
Summary:
Researchers have examined what factors drive hair variation in a
wild population of lemurs known as Indriidae. Specifically, the
researchers aimed to assess the impacts of climate, body size and
color vision on hair evolution.



FULL STORY ==========================================================================
Hair is an important feature of primate -- including human -- diversity
and evolution, serving functions tied to thermoregulation, protection, camouflage and signaling. However, the evolution of wild primate hair
remained relatively understudied until recently.


========================================================================== Researchers in the Primate Genomics Lab at the George Washington
University examined what factors drive hair variation in a wild
population of lemurs known as Indriidae. Specifically, the researchers
aimed to assess the impacts of climate, body size and color vision on
hair evolution. They found:
* Sifaka lemurs, which are native to Madagascar, have denser hair
in dry,
open environments. The researchers believe that, like early humans,
the lemurs' hair helps protect against the strong rays of the sun.

* Lemurs in colder regions are more likely to have dark hair. This
is the
first evidence in mammals for a classic pattern in nature called
Bogert's Rule, which states that dark colors could aid with
thermoregulation as they help absorb heat from the sun's rays.

* Red hair in lemurs is associated with enhanced color
vision. According to
the researchers, populations that can see a larger range of colors
are more likely to have patches of red hair.

* Multiple evolutionary pressures may act on one trait and the
strength of
their influence may vary between species.

"Human hair evolution remains a mystery, largely because hair does
not fossilize," Elizabeth Tapanes, lead author on the paper and
a postdoctoral scholar at the University of San Diego, California,
said. (Tapanes conducted the study while a doctoral student at GW.) "The
lemurs we studied exhibit an upright posture like humans and live in
a variety of ecosystems like early humans, so our results provide a
unique window into human hair evolution." Brenda Bradley, an associate professor of anthropology who directs GW's Primate Genomics Lab and is
a co-author on the study, explained 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." 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.


========================================================================== Story Source: Materials provided by George_Washington_University. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Elizabeth Tapanes, Rachel L. Jacobs, Ian Harryman, Edward E. Louis,
Mitchell T. Irwin, Jason M. Kamilar, Brenda J. Bradley. Hair
phenotype diversity across Indriidae lemurs. American Journal of
Biological Anthropology, 2022; DOI: 10.1002/ajpa.24508 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220309104414.htm

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