Human Evolution Accelerating?

Foxnews is reporting that researchers now believe that human evolution has accelerated in the recent past:

"If evolution had been proceeding steadily at the current rate since humans and chimps separated 6 million years ago, there should be 160 times more differences than the researchers found.

That indicates that human evolution had been slower in the distant past, Harpending explained.

"Rapid population growth has been coupled with vast changes in cultures and ecology, creating new opportunities for adaptation," the study says. "The past 10,000 years have seen rapid skeletal and dental evolution in human populations, as well as the appearance of many new genetic responses to diet and disease."

Well, the first problem is that humans and chimpanzees didn't split at 6 million years ago--not if the dates on Sahelanthropus and Orrorin are correct. It had to have been more like 8 million years ago. The second thing that strikes me is that one of the first things I learned in graduate school is that teeth have shrunk in size 11% since the neolithic. That seems like a striking change to me. I have not read the PNAS article yet, but the changes in culture and ecology can be largely attributed to increases in population. Anytime you get more people working on a problem independently, the problem gets solved faster.