The politics of chimpanzee societies is a complex affair. From waging warfare against other communities to climbing the social ladder, there is a constant battle to keep on top. But while it obviously pays to be the alpha male in a group, a new study has found that it is also beneficial to have friends in high places.
The dominant male in a community will have first choice of the females in that group, but this monopoly of mates is difficult to keep hold of, as the alpha has to juggle keeping other males away as they come into heat, particularly when multiple females are doing so at the same time. This results in a situation where not all the offspring born within a community are sired by the alpha male, as subordinates will constantly try and sneak off with females, or go on ‘safari’ with them.
Yet a new study, published in the Proceedings of the Royal Society B, looked into the detailed recordings of social interactions and mating between chimpanzees at Gombe National Park in Tanzania spanning 36 years and eight alpha male tenures. The researchers found that it wasn’t quite as simple as the lower ranked males getting in on the action when the dominant chimps' heads were turned. Instead, they found that the subordinate males would befriend the top ranking males, who would then allow them to mate with females in his presence.
“Alpha males may concede matings to subordinates in exchange for social favors, such as support in fights against other males,” explained University of Arizona’s Joel Bray, who led the study. This makes sense to the chimp at the top, as while the lower male may benefit in the short term by having offspring and spreading his genes, it is most likely that the male at the top will benefit in the long term as they can stay in power for longer by having the backing of the subordinate males.
This finding backs up other short-term exchanges that have found that alpha males will tolerate lower ranking males mating with females if the subordinate has just groomed the dominant, but it will be interesting to see how it relates to other dominance hierarchies in chimp societies.
“In the future, we also want to look at whether alpha males vary in the degree to which they concede matings,” said Ian Gilby, who co-authored the paper. “Large males that are firmly in control may have little to gain, whereas smaller alphas with a more tenuous hold on their dominance position may benefit by offering favors to subordinates to placate them or earn their support in fights.”
So it seems that even for chimps, it pays to have friends in high places.
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