Human mutation rate has slowed recently

January 23, 2019 by Christina Troelsen, Aarhus University

Researchers from Aarhus University, Denmark, and Copenhagen Zoo have discovered that the human mutation rate is significantly slower than for our closest primate relatives. This new knowledge may be important for estimates of when the common ancestor for humans and chimpanzees lived—and for conservation of large primates in the wild.

Over the past million years or so, the human mutation rate has been slowing down so that significantly fewer new mutations now occur in humans per year than in our closest primate relatives. This is the conclusion of researchers from Aarhus University, Denmark, and Copenhagen Zoo in a new study in which they found new mutations in chimpanzees, gorillas and orangutans, and compared them with corresponding studies in humans.

Using whole-genome sequencing of families, it is possible to discover new mutations by finding genetic variants that are only present in the child and not in 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. Until now, however, there have not been any good estimates of mutation rates in our closest primate relatives," says Søren Besenbacher from Aarhus University.

The study looked at 10 families' fathers, mothers and offspring: seven chimpanzee families, two gorilla families and one orangutan family. In all the families, researchers found more mutations than would be expected on the basis of the number of mutations that would typically arise in human families with parents of similar age. This means that the annual mutation rate is now about one-third lower in humans than in apes.

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