Social grooming network in captive chimpanzees: does the wild or captive origin of group members affect sociality?
Résumé
Many chimpanzees throughout the world are
housed in captivity, and there is an increasing effort to
recreate social groups by mixing individuals with captive
origins with those with wild origins. Captive origins may
entail restricted rearing conditions during early infant life,
including, for example, no maternal rearing and a limited
social life. Early rearing conditions have been linked with
differences in tool-use behavior between captive- and
wild-born chimpanzees. If physical cognition can be
impaired by non-natural rearing, what might be the consequences
for social capacities? This study describes the
results of network analysis based on grooming interactions
in chimpanzees with wild and captive origins living
in the Kumamoto Sanctuary in Kumamoto, Japan.
Grooming is a complex social activity occupying up to
25 % of chimpanzees’ waking hours and plays a role in
the emergence and maintenance of social relationships.
We assessed whether the social centralities and roles of
chimpanzees might be affected by their origin (captive vs
wild). We found that captive- and wild-origin chimpanzees
did not differ in their grooming behavior, but that
theoretical removal of individuals from the network had
differing impacts depending on the origin of the individual.
Contrary to findings that non-natural early rearing
has long-term effects on physical cognition, living in
social groups seems to compensate for the negative
effects of non-natural early rearing. Social network analysis
(SNA) and, in particular, theoretical removal analysis,
were able to highlight differences between individuals
that would have been impossible to show using classical
methods. The social environment of captive animals is
important to their well-being, and we are only beginning
to understand how SNA might help to enhance animal
welfare.