Wanna know the difference between this kid and a chimpanzee? So do evolutionary biologists . . . And with the use of genetic studies, scientists recently have figured out two additional ways that we Homo Sapiens differ from our common primate chimp ancestors from six to eight million years ago. They have to do with fat and spit.
One recent study demonstrated that human saliva is more watery than other living primates, having proteins that can help us digest fat better. (Other primates chew their food for much longer than we.) The second study is about our body’s fat cells — we have a much harder time at turning unhealthy “white” fat cells into healthy “brown ” fat ccells.
Why these adaptions? First, human saliva has an ability to break apart starches — and that was good, considering their diet had a lot more fat. It means our bodies might be able to take in energy more efficiently– something that the invention of cooking also helped with. Second, an abundance of white fat cells has made us fatter than the ancestral forebearers of modern apes. This also is good for enabling us to access more energy than brown fat cells would.
Health experts today might lament the fact that we have so many white, versus brown, fat cells, but the extra energy would have been excellent for our large brains. When our ancestors split off from modern apes’, their brain size remained the same but ours grew. And brains take up a very disproportionate amount of energy — it is about 25% of our caloric needs.
Source(s): Science Daily, June 26, 2019, “What made humans the fat primate?” And op.cit., “A secret in saliva: food and germs helped humans evolve into unique member of great apes.” October 16, 2019.
