AMHERST, Mass. — An international team of scientists led by a recent doctoral graduate from the University of Massachusetts Amherst sheds new light on the social behaviors of Kinda baboons (Papio kindae), revealing a remarkably affiliative relationship between males and females. The study, conducted over nine years in Zambia's Kasanka National Park, highlights how male Kinda baboons cultivate long-term social bonds with females, a trait that sets them apart.
Unlike most baboon species, where female social bonds dominate and male-female relationships are often short-lived or revolve around mating, the research led by anthropologist Anna Weyher , founder of the Kasanka Baboon Project , shows that male Kinda baboons actively initiate and maintain strong, enduring friendships with multiple females. These relationships persist across female reproductive states, indicating that they serve a social function beyond reproduction. The findings are published in the American Journal of Biological Anthropology .
"In some ways it's not surprising that, behaviorally, Kindas are so different because, anatomically, they look a lot different than other baboons," says Jason Kamilar , professor of anthropology at UMass Amherst, who co-authored the study. "Kindas are the smallest baboons and they're also the least sexually dimorphic, so the difference in body size between males and females is the smallest — making them the best baboon species [for us] to understand humans."
Male Kindas were observed initiating most interactions, maintaining proximity and engaging in frequent grooming of females, a behavior typically associated with social bonding in primates. The study reveals that these male-female friendships often lasted for years, a rarity among baboons.
Another discovery was the notably low level of aggression among male Kindas. While in other baboon species, males engage in frequent dominance struggles and aggressive competition for mates, Kinda males displayed minimal aggression toward each other and their female counterparts.
"What we'll typically see is that a male from outside the group will enter the study group, but they do so without much fanfare," Kamilar explains. "The new male will have to slowly move his way up the social hierarchy. That's very different from yellow baboons, for instance, where you'll have an individual male come in as an alpha and basically take over the group."
Instead of competing aggressively, male Kinda baboons appear to invest in a "long-game" strategy of social bonding, which may yield benefits such as increased reproductive opportunities and social support. Females, in turn, appeared to benefit from these bonds through reduced harassment and increased protection.
The study's findings challenge the traditional classification of baboon social structures. Historically, baboons have been categorized into two main social models: the "savannah" type, where female bonds are central, and the "hamadryas" type, where males dominate social interactions. However, Kinda baboons exhibit a mosaic of behaviors, with male-driven social investment reminiscent of hamadryas baboons but within a more fluid and egalitarian group structure.
This discovery also has implications for understanding primate evolution, as Kinda baboons may represent an ancestral baboon phenotype. The study suggests that their unique social structure could offer insights into the evolutionary pressures that shaped primate social behaviors, including those of early humans.
The research was supported by The Fulbright Program, American Society of Primatologists, Lambda Alpha, PEO International, Idea Wild, the Center for Evolution and Medicine at Arizona State University, and the Leakey Foundation.
