2010 Vol 101.pdf (1.63mb) - Primate Society of Great Britain

integration as a promoter of social success (support), measured by level of
integration in the group and level of stress exhibited. Female capuchins (n =
6) are members of two separate (East and West) but environmentally similar
groups of captive female capuchin monkeys (Cebus apella) housed at the
Living Links to Human Evolution research centre at Edinburgh Zoo.
Behaviour such as grooming (given and received), time spent alone or with
group members, dominance and scratching (as a measure of stress) were
documented by both scan and focal methods. Social integration was
calculated by mean time spent alone or with others. Statistical analysis
revealed significance between level of integration and the percentage of
time spent grooming others. All other analyses were non-significant;
however, mean amounts of scratching were lower when percentage of time
spent grooming was higher; also level of social integration illustrated some
relevance to rank position and amount of time spent grooming. To
conclude, this suggests that grooming is a commodity traded for a central
position in the group, to reduce stress, as well as to maintain rank position.
Bonobos (Pan paniscus) use copulation calls as a social signal
Z. Clay and K. Zuberbühler
Department of Psychology, University of St Andrews
Females of many primate species produce distinct vocalisations known as
‘copulation calls’ during mating events. Typically, copulation calls are
produced during heterosexual matings and thus their adaptive significance
is considered to be for promoting reproductive success. However, in
bonobos (Pan paniscus), females regularly engage in homosexual as well as
heterosexual matings and produce copulation calls in both contexts. The
way in which copulation calls have become detached from their biological
function in bonobos challenges theories explaining these calls as purely
reproductive strategies. In the current study, we examined bonobo
copulation calling behaviour to investigate how females use these
vocalisations as tools to pursue certain social and reproductive goals. We
recorded copulation calls produced by mature females at Lola Ya Bonobo
Sanctuary, DRC, during both homosexual and heterosexual interactions.
Acoustic analyses revealed considerable similarity in the acoustic structure
of copulation calls produced in both contexts. Furthermore, whilst females
called more during heterosexual copulations, we found that copulation calls
were used similarly in both contexts. For both homo- and heterosexual
copulation calls, we observed strong effects of relative dominance rank,
with low-rank females calling more with higher-ranked partners. In
homosexual matings, the identity of the initiator also predicted calling. Our
results suggest that bonobos use copulation calls as social signals to express
social status and to advertise bonding relationships. Thus, rather than being
restricted to purely reproductive contexts, copulation calls in bonobos
appear to have assumed a greater social significance.
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