New mutations occur at increasing rates in the mitochondrial genomes of developing egg cells in aging rhesus monkeys, but the increases appear to plateau at a certain age and are not as large as those seen in non-reproductive cells, like muscle and liver. A new study using incredibly accurate DNA sequencing methodology suggests that there may be a protective mechanism that keeps the mutation rate in reproductive cells relatively lower compared to other tissues in primates, a fact that could be related to the primate—and therefore human—propensity to reproduce at later ages.
