Social relationships between chimpanzee sons and mothers endure but change during adolescence and adulthood.


Mothers provide indispensable care for infants in many mammalian species. In some long-lived species, the maternal-offspring bond persists after infancy with mothers continuing to provide resources and social support to their adult progeny. Maternal presence is associated with fitness benefits through adolescence for male chimpanzees despite the fact that mature males dominate females and form their strongest bonds with other males. How mothers support grown sons is unknown, because few studies have examined developmental shifts in mother-son relationships during adolescence and adulthood. We investigated social interactions between 29 adolescent (9-15 years) and young adult male (16-20 years) chimpanzees and their mothers at Ngogo in Kibale National Park, Uganda over 3 years. All males under 12 years old had their mother as their top grooming and proximity partner, as did one-third of the young adult males. As males grew older, the amount of time they associated with, maintained proximity to, groomed with, and kept track of their mothers while traveling decreased. When males were together in the same party as their mothers, however, young adult males affiliated with their mothers as frequently as did adolescent males, with sons initiating the majority of these interactions. In contrast to adult sons, however, adolescent sons became distressed when separated from mothers and relied on their mothers for agonistic support and reassurance after conflicts. These findings indicate that the chimpanzee maternal – offspring bond continues but changes through adolescence and adulthood, with mothers remaining occasional social companions for most adult sons and frequent companions for some.

Last updated on 11/26/2020