According to research recently published in Nature Ecology and Evolution, humans today are mutating at a slower pace than our ancestors – and other species of primates. Not only does this mean we're unlikely to develop any X-men-style superpowers anytime soon, it straightens out a few inconsistencies in the evolutionary timeline.
Science has a fairly good understanding of human mutation rates but research into mutation rates in other primates has been lacking. And so experts at Aarhus University, Denmark, and Copenhagen Zoo have attempted to rectify the situation by whole-genome sequencing ape families – seven chimp families, two gorilla families, and one orangutan family.
"Over the past six years, several large studies have done this for humans, so we have extensive knowledge about the number of new mutations that occur in humans every year," Søren Besenbacher from Aarhus University said in a statement.
"Until now, however, there have not been any good estimates of mutation rates in our closest primate relatives."
The result – the human annual mutation rate is about one-third lower than the mutation rates of other apes. The researchers are not entirely sure what caused this slowdown but suspect it could have something to do with changes in our environment or that it may relate to our later puberty and longer generational timespans.
Whatever the reason, it has important implications when it comes to our evolutionary timeline, specifically when we split away from the other great apes.
In the past, estimates based on mutation rates have been inconsistent with the fossil record. For example, based on human mutation rates alone, scientists put the point of divergence between humans and orangutans at 35 million years ago. The physical evidence, however, suggests this split occurred 20 million years ago at the very earliest.
But apply these new mutation rates and the team at Aarhus estimate the divergence between humans and orangutans materialized approximately 15.9 million years ago, while the divergence between humans and gorillas happened some 9.1 million years ago. They also estimate the separation between humans and chimpanzees took place roughly 6.6 million years ago, rather than the 10 million years you end up with if you apply human mutation rates only.
The more ape genomes are sequenced, the surer we can be of the predictions. Still, in summary, the research pushes all speciation rates closer to the present. And that doesn't only apply to living primates but to our extinct hominid relatives, like the Neanderthals, too.
"The times of speciation we can now calculate on the basis of the new rate fit in much better with the speciation times we would expect from the dated fossils of human ancestors that we know of," Mikkel Heide Schierup from Aarhus University added.
There are also practical implications. Experts at Copenhagen Zoo say it could help conservation efforts directed at the great apes.
"All species of great apes are endangered in the wild," said Christina Hvilsom, who works in research and conservation at Copenhagen Zoo.
"With more accurate dating of how populations have changed in relation to climate over time, we can get a picture of how species could cope with future climate change."