Human mutation rate slowing behind that of primate relatives, study finds | Science & Tech News

New research has discovered that the human mutation rate is slowing significantly behind that of our closest primate relatives.

Genomic mutations play a key part in evolution, but new work by researchers from Aarhus University and Copenhagen Zoo in Denmark have found that humanity’s genome is not changing very much at all.

The scientists found that over the past million years, humanity’s genome has been lagging behind that of chimpanzees, gorillas and orangutans.

By sequencing the entire genome of families, researchers attempted to identify new mutations by spotting genetic variations which were only present in the children and not the parents.

“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,” said Spren Besenbacher of Aarhus University.

“Until now, however, there have not been any good estimates of mutation rates in our closest primate relatives.”

The study examined 10 families’ parents and offspring: seven chimpanzee families, two gorilla families and one orangutan family.

A chimpanzee smiling
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Humans could have separated from chimpanzees more recently than thought

Researchers found more mutations in all of the families than expected compared to existing studies of human genomic variations – meaning human’s annual mutation rate is roughly a third lower than that of apes.

This has significant repercussions on the length of time previously thought to have passed since the most recent common ancestor of both humans and chimpanzees – because the genetic differences between the two species will have accumulated over a shorter period.

Applying the higher mutation rate for apes, scientists estimate that humans and chimpanzees separated roughly 6.6 million years ago – compared to 10 million years ago going by the mutation rate for humans.

“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,” explained Mikkel Heide Schierup from Aarhus University.

This reduction in the human mutation and thus evolution rate could also mean that humans and Neanderthals could have split more recently than currently estimated.

Christina Hvilsom from Copenhagen Zoo added that the findings could have major repercussions on great ape conservation projects.

“All species of great apes are endangered in the wild,” she said.

“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.”

The study, “Direct estimation of mutations in great apes reconciles phylogenetic dating”, has been published in Nature Ecology and Evolution.

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