Dating of the human ape splitting by a molecular clock

Yet, ages gleaned from the fossil record are often somewhat imprecise.

One way to directly pin down the rate of mutation in a species is to compare members of that species with their progeny.

"Our results indicate that human and chimp ancestors' genomes would diverge by about 0.1 percent every million years, so when we see divergence of 1.2 percent, we infer that it must have been about 12 million years — 13 million years is our actual estimate," Mc Vean told Live Science.

Dating of the human ape splitting by a molecular clock

But, calibrating how fast these molecular clocks actually tick can be challenging; the molecular clock of one species might conceivably tick faster or slower than that of another species, the scientists said.

Researchers usually try to overcome this challenge by comparing molecular clocks to the fossil record to see when species diverged.

The genes that children get from their parents may possess mutations caused by factors such as radiation, mutation-triggering chemicals or errors during cell division.

By counting the number of genetic changes that accumulate over generations, scientists can estimate the rate at which mutations occur in that species.

To see if chimpanzees have similar patterns of mutation, scientists analyzed nine related western chimpanzees () spanning three generations.