I quote the other interesting comment on Slave Species of God here as well :
"Michael Tellinger has started a monthly newsletter where he sends out information of the latest discoveries regarding the topics he talks about in his book. I found a few articles this week myself on Google news that slowly makes the puzzle of our murky past seems like it is not so far fetched after all?? I strongly suggest that you go to the Slave Species website and subscribe.
I include the article from the Washington post to wet your appetite. Keep exploring.
HUMAN ANCESTORS MAY HAVE INTERBRED WITH CHIMPANZEES
When Nick Patterson of MIT and his colleagues at the Broad Institute compared the genes of humans and chimps, they found that one of the chromosomes -- the female sex chromosome X -- was 1.2 million years younger than the others. It appeared the two species shared a common ancestor who gave them both their X chromosomes, and did so more recently than the ancestors who gave them all the other chromosomes.
The best explanation, the scientists think, is that ancient humans and chimps broke away from each other not once, but twice. The first time was more than 6.3 million years ago. The second time was at least a million years later. What probably happened was that some of the evolving human ancestors bred with the evolving chimps. This was perhaps not as strange as it seems, for although there were some physical differences between the two groups, "the early humans must have looked pretty much like chimpanzees," said Mallet, the London geneticist.
Males have only one X chromosome, which is necessary for reproduction. As is often the case with hybrids, the male offspring from these unions would probably have been infertile.
But the females, which have two X chromosomes, would have been fertile. If some of those hybrid females then bred with proto-chimp males, some of their male offspring would have received a working X from the chimp side of the family. They would have been fertile -- and with them the hybrid line would have been off and reproducing on its own.
The evolutionary clock indicates this happened no more than 6.3 million years ago, and perhaps as recently as 5.4 million years ago. In that case, the fossils of older species -- such as Toumai, or Sahelanthropus tchadensis, a proto-man from Chad that had a humanlike brow and probably walked on two feet -- must have belonged to descendants of the first human-chimp divergence.
That line must have died out. If it had not, modern man's X chromosome would look as old (or nearly as old) as the other chromosomes.
"I think the most interesting thing [is] this idea that long, extended gene flow seems to have occurred and that this might be a creative mode of evolution," said David Reich, a geneticist at Harvard Medical School. He is one of the authors of the study, which appears in today's issue of the journal Nature.
The idea that new species emerge in a slow and stuttering fashion was favored by Charles Darwin, Mallet said. But in the early part of the 20th century, biologists came to favor the idea of clean breaks, with the "pure" lines of emerging species being stronger and fitter than hybrids.
In fact, Mallet said, about 10 percent of animal species are capable of interbreeding with related species, even though the number that do so in any population is very small.
By David Brown Washington Post Staff Writer - Thursday, May 18, 2006"