Chimpanzees inherit 90 percent of their new mutations from their fathers, a characteristic that can explain the difference between humans and the animal.
Chimpanzees are human's closest living relatives. A new study found answers to questions about the key differences between humans and the animal. Researchers of the study revealed that chimpanzees inherit 90 percent of their new mutations from their father and only 10 percent from their mother, something that is not seen in humans.
Human inherit about 70 percent of new mutations from their parents. This number is highly influenced by factors like the father's age. Previous studies have revealed that older fathers pass on more mutations to their offspring - two more mutations for every extra year of age. A father's age plays a bigger role in new mutations because while the sperm lineage in males keeps dividing, females are born with all the eggs they are ever going to produce. This also explains why paternal age is a major influencing factor in disorders like autism and schizophrenia.
"In humans, a father's age is known to affect how many new mutations he passes on to his children, and is also an established risk factor in a number of mental health disorders," Professor Gil McVean from the University of Oxford said in a press statement. "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 per cent, compared to humans, where fathers account for 75 per cent of new mutations."
Any change in the genetic sequence of an offspring that is not seen in either parent is considered to be a new mutation. For the study, researchers sequenced the genomes of nine western chimpanzees from a three generation family living at the biomedical primate research centre in the Netherlands.
Chimpanzees have testes that are over three times the relative size of a human, which enables them to produce more sperms. This increases the number of sperm production cycles, which in turn increases the chances of new mutation to emerge. This probably explains the new mutation inheritance difference between the animal and humans.
Study authors said that more research needs to be conducted on mating behavior to see how it affects mutation rates and male mutation bias. The current study was funded by the Wellcome Trust. Findings were published in the journal Science.
