Assumptions about the lack of fathering skills of male chimpanzees have been challenged, with the discovery that males spend time caring for their children, even when it doesn't increase their chances of sex with the mother.
Chimpanzees are a promiscuous species. Dominant males will father offspring with many females. Those lower down the pecking order have found creative ways of passing on their genes, with research published this week showing this includes making friends with the alphas.
Primatologists assumed male chimps didn't invest any effort in helping to raise their children. The most successful males would have too many to keep track of, went the logic, and anyway the young chimp's paternity was often uncertain.
However, the Jane Goodall Institute has created a phenomenal database of observations of the behavior of eastern chimpanzees (Pan troglodytes schweinfurthii) of the Gombe Stream National Park, Tanzania. Since 1989, this has included genetic cataloging of familial relationships. When Dr Carson Murray of George Washington University analyzed the interactions of 17 fathers and 49 mother-infant pairs she found that males would spend much more time grooming and protecting their children than with more distantly related young chimpanzees.
In some species, such behavior might lead to the fathers being rewarded by a chance to mate with the mothers again. This didn't seem to be the case in Gombe. Murray reported in Royal Society Open Science that the mothers were still nursing their babies and not ready for a new child, during the periods studied. By the time they could mate again, they didn't reward the fathers of their previous children. Fathers who spent time around nursing mothers were no more likely to father the next child than their rank in the hierarchy would suggest.
Moreover, Murray suspects the fathers paid a price for this behavior, missing out on chances to increase their status among the other males.
"As anthropologists, we want to understand what patterns could have existed early in human evolution that help explain how human behavior evolved," Murray said in a statement. The other great apes give us some insight into that question.
Early human societies may not have closely resembled those of chimpanzees, but Murray's work suggests, at the very least, that paternal recognition may go deeper in our ancestry than we realized.
Evolutionary psychologists have divided males into two groups, “Cads” and “Dads". The former try to have as much sex as possible to increase the chances of passing on their genes, but do nothing to support their offspring. The latter have fewer children, but take care of them to give them the best chance in life. However, this has been criticized as overly simplistic, and Murray's work may support those criticisms.
It's been a big week for research on chimpanzee behavior. The same edition of Royal Society Open Science includes a paper reporting that chimpanzee mothers use babysitters to encourage their children to become more independent. Those raised in this way consumed less milk from their mothers and were able to be weaned more quickly than where the mother had to manage on her own.