A Friendlier "Kinda" Social System: Male Kinda Baboons Invest in Long-Term Social Bonds With Females

Certain group-living mammals-including many primates-exhibit affiliative relationships between sexes that persist past copulation. Relationships between females and males in baboons (Papio sp.) are particularly well-characterized. These relationships tend to revolve around the female reproductive cycle and are generally female-initiated and female-maintained. Kinda baboons (P. kindae) appear to diverge phylogenetically and behaviorally from other baboons. Here, we assess how Kinda baboons differ socially by characterizing female-male relationships using 9 years of data on a population in Kasanka National Park, Zambia.

We used generalized linear mixed models to assess grooming rates and directionality for individuals and among female/male dyads, patterns of between-sex proximity, and rates of agonistic behavior. We examined these patterns across female reproductive states and evaluated the degree to which dyadic affiliations persisted over time.

We find that female-male relationships in Kinda baboons are characterized by a high degree of male investment with low aggression that persists across female reproductive states and years. We find that females have strong affiliations with a single male while males have strong affiliations with multiple females at a time. Males are largely responsible for initiation, grooming, and proximity in affiliative relationships with females, and dyads often persist across years.

Our results suggest that Kinda baboons represent a mosaic of baboon social features and, paired with recent genomic evidence about their population history, may resemble the ancestral baboon phenotype. This expands our understanding of the "baboon model" for comparative socioecology and emphasizes the high variability and evolvability of social phenotypes.