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Comparing features of a 4.4-million-year-old fossil skeleton to those of human and chimpanzee skeletons sheds light on our evolutionary history.

That acoustic convergence suggests that an important element of language cognition may have been present 7 million to 13 million years ago, in the last common ancestor of chimpanzees and humans.

WASHINGTON - The National Institutes of Health is sending its last remaining research chimpanzees into retirement - as soon as a federal sanctuary has room for them. The government already had declared that the use of humans' closest relative as a test subject was coming to an end. In 2013, the NIH said it would retire most of the several hundred government-owned chimps still living at research laboratories. But it set aside 50 animals to be on standby just in case they still were needed for a public-health emergency or some other extreme situation. Wednesday, the agency said those chimps' lab days are over, too.

Humans may in part owe their big brains to a DNA "typo" in their genetic code, research suggests. The mutation was also present in our evolutionary "cousins" - the Neanderthals and Denisovans. However, it is not found in humans' closest living relatives, the chimpanzees. As early humans evolved, they developed larger and more complex brains, which can process and store a lot of information. Last year, scientists pinpointed a human gene that they think was behind the expansion of a key brain region known as the neocortex.

A Cornell study offers further proof that the divergence of humans from chimpanzees some 4 million to 6 million years ago was profoundly influenced by mutations to DNA sequences that play roles in turning genes on and off.

The researchers isolated different subpopulations of human brain stem cells and precisely identified, which genes are active in which cell type. In doing so, they noticed the gene ARHGAP11B: it is only found in humans and in our closest relatives, the Neanderthals and Denisova-Humans, but not in chimpanzees. This gene manages to trigger brain stem cells to form a bigger pool of stem cells. In that way, during brain development more neurons can arise and the cerebrum can expand. The cerebrum is responsible for cognitive functions like speaking and thinking.