Researchers trying to pin down how frequently mutations crop up in humans have come up with different estimates, writes Ewen Callaway at Nature News. He adds that these estimates also seem to indicate that the rate is variable and has slowed.
This slower rate, which was established by comparing the genome sequences of parents and children and is about half the older rate, helps bring genetic and archeological findings about human migrations and origins into alignment, but for older events, the slower rate stops making sense, Callaway says.
Researchers, he further reports, have met recently to hash out why there appear to be these differences in calculated mutation rates, whether mutations rates fluctuate and why, as well as how this affects fields ranging from evolutionary biology to medicine.
At the meeting, Harvard Medical School's David Reich suggested that, for now, researchers rely on the slower mutation rate until a better gauge comes along, warning against thinking of the rate as a constant, according to Callaway. "This is not the speed of light. This is not physics," Reich says.