Gorillas may be the key to understanding human fatherhood


Contrary to the popular notion of the raging alpha male beast, a study on mountain gorillas shows that the best reproductive and evolutionary strategy is fatherhood.

It is not unusual for animals, such as lions, to dispose of the cubs of other animals should they knock the competition out of contention. However, a previous study in Rwanda revealed that mountain gorillas seem to share the quirk of caring for kids, even if those kids are not their own but are part of the same social sphere. What a recent study aimed to do was answer why a male gorilla would protect and become fatherly to children that are not his.

“Mountain gorillas and humans are the only great apes in which males regularly develop strong social bonds with kids, so learning about what mountain gorillas do and why helps us understand how human males may have started down the path to our more involved form of fatherhood,” said Stacy Rosenbaum, lead author of the study and a post-doctoral fellow in anthropology at Northwestern.

“We’ve known for a long time that male mountain gorillas compete with one another to gain access to females and mating opportunities, but these new data suggest that they may have a more diverse strategy,” Rosenbaum added.

“Even after multiple controls for dominance ranks, age and the number of reproductive chances they get, males who have these bonds with kids are much more successful.”

This seems to allude to a possible origin of humanity’s own fathering skills as well as an explanation of the popularity of polygamy — specifically polygyny, or having multiple wives — for humans in prehistoric times as well as in the rest of the animal kingdom.

Though monogamy is favored in most parts of the world these days, humanity has practiced polygyny for the majority of its existence as it made sense evolutionarily to do so. Additionally, it made sense evolutionarily to take care of kids in order to have a greater chance of spreading genes since the presentation of a father figure who can provide the most fatherly guidance and care to offspring attracts more females.

In human males, this trait is somewhat transferable, considering testosterone levels decrease after the birth of a child, presumably because the male is no longer on the hunt for reproduction and therefore does not need to produce as much facial hair, muscle or heat to attract a mate.

Additionally, the reduction of aggressiveness caused by the testosterone aids in the development of the newborn.

“In human males, testosterone declines as men become fathers, and this is believed to help focus their attention on the needs of the newborn,” said Christopher Kuzawa, a co-author of this study and a researcher who co-authored a study on the same topic in the journal Proceedings of the National Academy of Sciences in 2011.

“Might gorillas that are particularly engaged in infant interaction experience similar declines in testosterone? Because this would probably impede their ability to compete with other males, evidence that testosterone goes down would be a clear indication that they must be gaining some real benefit — such as attracting mates. Alternatively, if it does not go down, this suggests that high testosterone and caretaking behavior don’t have to be mutually exclusive in mountain gorillas.”

The researchers aim to answer these questions in depth in the coming months with the help of long-term knowledge of the way hormones function in response to life situations.