Meat is a rare and highly prized resource for wild Guinea baboons (Papio papio). Yet, contrary to long-standing assumptions based on human hunter-gatherer societies, a new study by the German Primate Center – Leibniz-Institute for Primate Research (DPZ) now reveals that female Guinea baboons do not preferentially choose males who are more skilled at acquiring meat as their mates. The research team led by William J. O’Hearn (DPZ & University of Exeter, UK) additionally shows that female Guinea baboons are less dependent on their primary male for access to meat than previously thought after documenting the first-ever case of female-initiated prey capture. The results, now published in the American Journal of Biological Anthropology, throw new light on the evolutionary origins of meat provisioning as a male quality signal in primates.

The practice of catching and sharing prey as a signal of male quality has both deep evolutionary roots and a pertinence to human’s evolutionary trajectory. In human hunter-gatherer societies catching prey can signal a male’s quality as a provider, and sharing the spoils of the hunt can broadcast that signal throughout the community. Guinea baboons offer a valuable analogy to the evolution of human food sharing practices through their parallel evolution with early human ancestors. Additionally, they exhibit multi-level social organization that parallels the nested social levels of human societies, in which the lowest level (baboon: unit; human: core family) consists of one primary male, one to several associated females, and their offspring.

A previous DPZ study also led by O’Hearn revealed how Guinea baboons share meat inside these social organizations: more frequent sharing occurs at the level of the closet social unit, akin to human hunter-gatherers first sharing their hunted prey within their direct family members. The current study now investigated whether meat-acquisition success and consequent meat-sharing acts as male quality signal in Guinea baboons, also resembling patterns found in human hunter-gatherer societies.

Female baboons are less dependent on their primary male than expected

To answer this question, researchers from the Cognitive Ethology Laboratory at the DPZ used observations made over nine years at the DPZ field station Simenti in Senegal. They combined annotated recordings of 109 specific meat-eating events with demographic and behavioral data from 465 individually identified baboons. In 11 percent of these events the prey was caught by a female – the first-ever observations of this behavior for Guinea baboons – and 41 percent of the meat eaten by females originated from sources other than their primary male.

In the previous study on Guinea baboon meat-sharing, male baboons transferred up to 40 percent of their caught prey to the females in their unit. While these results suggested that female baboons may depend on their males for access to meat, the new findings reveal that this dependency is not as pronounced as previously assumed. Still, a large share of the meat female baboons accessed originated from their primary male.

No female preference for more skilled male prey catchers or meat sharers

Additionally, statistical models revealed no link between a male’s frequency of meat acquisition or transfer and either the number of females in his unit or the length of female‑male associations. “Despite what we predicted, we found no evidence that females preferred to join or remain longer in the units of males who acquired or shared meat more often. Instead, females seem to get a substantial portion of their meat from sources other than their unit male, including simply catching the prey themselves,” says lead author William J. O’Hearn.

The largest factor for male mating success instead was age, with animals in their early- to mid-prime age having more associated females in their units than older males.

Other factors might influence female reproductive decisions

Taken together the results suggest that prey capturing and meat transfers are unlikely to be behaviorally relevant signals of male quality in Guinea baboons. This could in part be explained by the relative infrequency of meat-eating events in the life of wild-living baboons, which occur far less often than successful hunts among human hunter-gatherers. Instead, female reproductive decisions could be influenced by physical signals from the male baboon such as more strongly red tinted patches on their butts. Similar physical signals have been shown to signal male quality in other primates. Or, females could focus on behavioral or social signals such as a male’s tendency to care for its offspring or its behavior towards other females in the unit.

“Guinea baboons provide a particularly interesting evolutionary comparison to humans where similar ecological conditions and social systems have resulted in differences in the importance of meat sharing to female partner choice. Where females have many options for sourcing meat, it need not be a factor when choosing a mate,” says William J. O’Hearn.