Father's Age Impacts Rate of Evolution in Chimpanzees: High Number of Mutations

It turns out that mutation isn't the same for humans and chimps. Scientists have found that the offspring of chimpanzees inherit 90 percent of new mutations from their father, and a low 10 percent from their mother. The findings reveal the importance of a father's age when it comes to evolution.

In humans, each individual inherits about 70 new mutations from their parents. Yet this number is influenced by paternal age; each extra year of age actually results in two extra mutations. This mutation risk is linked to fathers because the sperm lineage in males keeps dividing, while females have all of the eggs they are ever going to produce present at birth.

In this case, the researchers focused on mutations in chimps. In the end, they found that the number of new mutations inherited by chimpanzees from their parents is very similar to that in humans. However, the effect of the father's age in chimps is much, much stronger. The findings suggest that sexual selection can actually influence the rate of evolution through its effect on male mutation rate.

"In humans, a father's age is known to affect how many new mutations he passed on to his children, and is also an established risk factor in a number of mental health disorders," said Gil McVean, one of the researchers, in a news release. "This study finds that in chimpanzees the father's age has a much stronger effect on mutation rate-about one and a half times that in humans. As a consequence, a greater fraction of new mutations enter the population through males, around 90 percent, compared to humans, where fathers account for 75 percent of new mutations."

So why the difference between chimps and humans? It's possible that the difference arises from the fact that a chimp produces far more sperm than a human, which increases the opportunity for new mutations to emerge. The findings reveal a bit more about mutations in chimps which could, in turn, shed light on mutations in humans.

The findings are published in the journal Science.