Climate Changed the Size of Our Bodies – and Our Brains
upstart writes:
Climate Changed the Size of Our Bodies - And Our Brains:
An interdisciplinary team of researchers, led by the Universities of Cambridge and Tubingen, has gathered measurements of body and brain size for over 300 fossils from the genus Homo found across the globe. By combining this data with a reconstruction of the world's regional climates over the last million years, they have pinpointed the specific climate experienced by each fossil when it was a living human.
The study reveals that the average body size of humans has fluctuated significantly over the last million years, with larger bodies evolving in colder regions. Larger size is thought to act as a buffer against colder temperatures: less heat is lost from a body when its mass is large relative to its surface area.
[...] A defining trait of the evolution of our genus is a trend of increasing body and brain size; compared to earlier species such as Homo habilis, we are 50% heavier and our brains are three times larger. But the drivers behind such changes remain highly debated.
"Our study indicates that climate - particularly temperature - has been the main driver of changes in body size for the past million years," said Professor Andrea Manica, a researcher in the University of Cambridge's Department of Zoology who led the study.
He added: "We can see from people living today that those in warmer climates tend to be smaller, and those living in colder climates tend to be bigger. We now know that the same climatic influences have been at work for the last million years."
Journal Reference:
Manuel Will, Mario Krapp, Jay T. Stock, et al. Different environmental variables predict body and brain size evolution in Homo [open], Nature Communications (DOI: 10.1038/s41467-021-24290-7)
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