Researchers from the University of Chicago report that about 25 percent of genes mutate in advantageous ways.

"These papers directly conflict with the "neutral theory," which has dominated genetic research since the 1960s. According to the neutral theory, many small genetic changes randomly occur, but the vast majority simply don't matter. Fewer than one percent make enough of a difference that they are either embraced or expunged by natural selection.

By comparing variation within the human genome and divergence from our ape ancestors, the researchers determined that about 35 percent of the accumulated changes were "good."

It means one advantageous substitution has entered the human genome every two centuries since humans separated from monkeys 30 million years ago."

By my reckoning, this could also be a set of 50 mutations occuring at 10,000 year intervals.

Extra: Duplicate monkey DNA evolves