Chimps and humans are 99% alike when it comes to DNA. Researchers think what makes us different are "lifestyle" changes that occurred 6 million years ago, when we both separated from a common ancestor. These have to do with how we smell and hear things and what we eat.
Evolutionary geneticist Andrew G. Clark says, "What are the genes that make us human? Or rather, what genes were selected by natural selection to result in differences between humans and chimps?" He found evidence of positive selection in the genes involved in the ability to sense and process odors. These genes are also involved in digestion of protein, in long-bone growth, hairiness and hearing. While chimps eat a little protein, in the form of insects, only human primates are hunters?which affected the way our bodies developed. Early humans started eating more meat about 2 million years ago, in response to climate change.
"This study also gives tantalizing clues to an even more complex difference?the ability to speak and understand language," Clark says. "Perhaps some of the genes that enable humans to understand speech work not only in the brain, but also are involved in hearing." One of the difficulties with trying to train chimps to understand language may be that their hearing is selective enough to distinguish subtle differences in sounds.
There's hunting and then there's?hunting.
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