Fossil DNA used to reset humanity’s clock

A painting in the Olduvai Gorge Museum, Ngorongoro Conservation Area, Tanzania.

Dongyi Liu

Some time in humanity’s past, a small group of Homo sapiens migrated out of Africa before spreading out to every possible corner of the Earth. All the women of that group carried DNA inherited from just one woman, commonly known as mitochondrial Eve, whose DNA was inherited by all humans alive today. But the exact timing of this migration is not clear, and it has sparked debate among geneticists. Now, new research published in Current Biology may help calm both sides.

Studies of evolutionary events often involve the use of molecular clocks based on changes in DNA that accumulate over time. To accurately calibrate a clock, it helps to have a measure of the rate of mutations.

In 2012, UK Researchers used a method of analysis that involves DNA from the nucleus of present day humans. Armed with data from parents and their offspring, they estimated a new, much lower rate of DNA mutation. Based on their results, it would seem that human DNA may change much more slowly than was previously thought. The slow mutation rate puts the date of human migration out of Africa at somewhere between 90,000 and 130,000 years ago.