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How man 'lost his penile spines'

Thanks to Ivan for the link.

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The study claims man lost the penile spines of other primates during evolution

Scientists believe men once had small spines on their genitalia such as those found in chimpanzees, cats and mice.

Analysis of the genomes of humans, chimpanzees and macaques indicates that a DNA sequence thought to play a role in the production of these spines have been deleted in humans, but has been preserved in other primates.

It suggests another genetic deletion may have led to the expansion of specific regions of the human brain.

The study is in the journal Nature.

The researchers at Stanford, Georgia and Pennsylvania State universities in the US wanted to trace evolutionary changes in human DNA.

They compared the human genome with those of the chimpanzee and macaque, and came up with 510 stretches of DNA that have been conserved in our primate relatives but deleted in humans.

Nearly all these DNA regions appear to play a regulatory role in the function of nearby genes.

The researchers then focused on two deletions, linking one to penile spines and another to the growth of specific areas of the brain.

They then tested the effects of the deleted sequences in human skin and neural tissue, and found further evidence to support their claims.

"We're trying to find the molecular basis of being human," said Professor David Kingsley of Stanford University, one of the authors of the study.

"That's a really ambitious goal; but we live at this unique time where we have the complete genome sequence of ourselves and our closest relatives, so you can systematically go through and find all the ways that we differ from other organisms."

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