Researchers found that in chimpanzees the hormone oxytocin
is likely to play a key role in maintaining social relations with both kin and
non-kin cooperation partners
Animals which maintain cooperative relationships show gains
in longevity and offspring survival. However, little is known about the
cognitive or hormonal mechanisms involved in cooperation. Researchers of the
Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have
now found that cooperative relationships are facilitated by an endocrinological
mechanism involving the hormone oxytocin, even when these are between non-kin.
They collected urine samples of 33 chimpanzees from Budongo Forest, Uganda, and
measured their urinary oxytocin levels after single episodes of a specific
cooperative behaviour, mutual grooming. The result: Oxytocin levels were higher
after grooming with cooperation partners compared with non-cooperation partners
or after no grooming, regardless of genetic relatedness or sexual interest.
This suggests that in chimpanzees oxytocin, which acts directly on neural
reward and social memory systems, plays a key role maintaining social relations
beyond genetic ties and in keeping track of social interactions with multiple
individuals over time.