Monkey business

Got your attention?

This just in:
Genetic evidence for complex speciation of humans and chimpanzees
Published in Nature, on the 29th of June. (You might not be able to see this article if you don't have a nature subscription...).

The authors looked at the genetic clocks in chimps and humans, which should be able to tell you when the two species diverged. However, they seemed to be ticking at different rates. Patterson et al. found that the least changes had happened along the X chromosome (the female chromosome). What did this mean? Well, they start of cloaking their suggestion in suitably modest terms:

"These unexpected features would be explained if the human and chimpanzee lineages initially diverged, then later exchanged genes before separating permanently."

Hmm, got it yet?

They later state:

"indicating an unusual history in the ancestral population at the time of speciation."

Unusual, hey? They concluded that:

"We suggest a provocative explanation for multiple features of these data: that the hominin and chimpanzee lineages initially separated but then exchanged genes before finally separating less than 6.3 Myr ago."

In case terse scientific prose is not your thing, here is a visual:

That's right, we're talking about monkey lurve...

Apparently, when humans first split from chimps, there was some monkey business going on for some time after. Its hard to picture, so here's another:

The authors tend to suggest that female chimp hybrids might have been fertile, and carried through the X-chromosome changes. That might be an easier to sell to a reputable journal than if it were the other way round. Although we do have some good evidence that humans are carrying chimp genes, and don't think anyone really needs any convincing: