Human evolution accelerating?

A study led by Robert K. Moyzis of the University of California, Irvine, and Henry C. Harpending of the University of Utah reports that approximately 7 percent of human genes shows signs of having evolved via natural selection since the emergence of modern humans. What's interesting is that the rate of genetic change in humans has apparently been accelerating over the last 50,000 years, producing such things as populations more resistant to certain diseases. The reason, apparently, is that people have exploded in numbers and pushed into more environments. Other researchers are cautious about the findings, noting that alternative explanations are possible and that the test for determining which genes have evolved may be faulty.