I know this for certain

Today I was reading a story on MSNBC.com. With a title like "Did chimp and human ancestors interbreed?," who wouldn't want to read it? What struck me in the article was not the stupidity of their speculation, but the sheer quantity of speculation. Consider some of these sentences. How can this be considered seriously?


The earliest known ancestors of modern humans might have reproduced with early chimpanzees…

…a new genetic analysis suggests.

…the scientists believe the split between the human and chimpanzee lines occurred much more recently than previously thought

… no more than 6.3 million years ago and perhaps as recently as 5.4 million years ago.

…Human and chimpanzee ancestors began branching apart on the primate evolutionary tree about 9 million years ago, scientists say, but there are significant gaps in the fossil record.

The new analysis suggests…

…nearly 4 million years and might have occurred twice….

…Based on an estimated relative mutation rate,

… around 6.3 million years ago. From start to finish, complete speciation spanned a much longer time range than in any other modern apes.

There are regions of the genome that don't appear to be much more than 5 million years old, and there are regions that appear to be 4 million years older than that.

…This suggests that after the first speciation 6.3 million years ago,

…early human ancestors may have lived and reproduced with ancestral chimps to produce hybrid primates.

…This would help explain why divergence on X between humans and chimps is so low

…Mixing and matching genetic information from two species doesn't always work out well,

…Patterson explains one possibility for how this could have happened: The initial split occurred around 6.3 million years ago.

…Sometime after, the descendants of the earliest known human ancestor mated with ancestral chimps and created a hybrid species.

..In this scenario, the earliest known human ancestor, a biped known as "Toumai" that probably didn't look much different than chimpanzee ancestors, would have predated the hybridization. The Toumai fossil, which was unearthed in Chad, has been dated back to somewhere between 6.5 million and 7.5 million years ago.

…Scientists can't say how long the hybridization carried on, but the final speciation occurred around 5.3 million years ago, possibly because the two species' genetic codes were too different to mix, or because the animals were simply physically unappealing to each other.

…If that occurred, they might have been compatible enough on X that it would fix out to one species or another," Patterson said. "As it happened, it fixed to chimps, but it could have gone the other way.

…This is just one possible explanation for the gap in speciation time...