Chimps are actually more evolved than humans

There is no doubt that humans are the more advanced species. But a comparison of 14,000 human and chimpanzee genes shows the forces of natural selection have had the greatest impact on our ape cousins.

The researchers' discovery challenges the common assumption that our large brains and high intelligence were the gifts of natural selection.

Humans and chimps followed different evolutionary paths from a common ape ancestor about 5million years ago.

Both underwent changes as the fittest survived to pass their genes on to future

tions. But the U.S. study shows that humans possess a 'substantially smaller' number of positively-selected genes than chimps.

This may be because the original human population was very small - which would have reduced the effectiveness of natural selection.

Instead, 'genetic drift' - the random survival of genetic mutations rather than their preservation by the laws of natural selection - was likely to have been more important in humans, according to the scientists, led by Dr Jianzhi Zhang from the University of Michigan at Ann Arbor.

"These observations refute the anthropocentric view that a grand enhancement in Darwinian-selection underlies human origins," they wrote in the journal Proceedings of the National Academy of Sciences.

The researchers also found that positive selection acted on different genes in humans and chimps, and the selected genes were involved in different processes.

Surprisingly, many positively-selected genes in humans were involved in inherited diseases.

This may be because we live in a very different environment from the one our ancestors inhabited, said the scientists.

Adaptive changes that were positive for early hominids may not be so beneficial, or may be even harmful, today.