to the power struggles within Sonso society. Grooming, as we noted, goes up the
hierarchy: individual males use grooming to appease and to please their superiors.
Alliance partners, who stand to gain from co-operating with each other against one or
more third parties, groom each other while they are allies, confirming their trust in
one another. Their relationships are, however, ‘fickle’ (Newton-Fisher 1997), and when
it no longer suits two males to ally but instead one decides to dominate the other, their
grooming partnership falls apart.
We have used grooming as an indication of affiliation and this is indeed a good indi-
cator. However, grooming is not the only way in which affiliation can be expressed.
There is evidence from Taï that certain dyads of females had higher association indices
(based on time spent together) than any of those between males, and in these cases the
high rate of association was not accompanied by a high rate of grooming each other.
Three pairs of adult females spent respectively 66%, 71% and 79% of their time together
(Boesch and Boesch-Achermann 2000). The females were of similar age and therefore
not thought to be sisters. The authors describe them as ‘friends’; they shared food and
supported each other in conflict situations. One such friendship lasted for four years, the
other two lasted for five years each and all ended only when one of the partners died.
The authors suggest that these female–female friendships may have been associated
with high inter-female competition at Taï (p. 107); there were 25 adult females in this
community, and the female friendship pairs had high status and a high rate of success in
food competition, as well as in helping their sons rise in the male hierarchy. They had,
it seems, transcended the tendency for females to be less sociable than males in their
own, and their sons’, interests. Boesch and Boesch-Achermann propose that the status
of females, higher in Taï society than in other chimpanzee communities studied, is based
on ‘stronger intra-group competition, a highly biased sex ratio, and large party size’
(p. 263). This would fit with the Budongo situation where the food supply is plentiful
and feeding competition is apparently not great for much of the year (see Chapter 4).
Play
Play of many kinds is seen at Sonso, mostly between juveniles when they happen to be
together in a party. Juveniles like to climb lianas, one after the other, and dangle from
thin branches together, and can play-chase for long stretches of time in such simple
ways. A proper account of play is not included here, but a single recent example is worth
recounting, in which the play, rather unusually, involved water:
On 8th February 2004 during a focal follow of Janie, her daughter Janet (aged almost four and a
half years) was seen leaf sponging in the river Sonso. 5 mins later she was observed splashing with
one hand in the water, from the bank of the river. Janie crossed the river on a pole bridge and Janet
followed, but stopped on the bridge. Nora (a late stage juvenile aged eight years) joined her on
the bridge and they both put one hand in the water and splashed, moving the water towards one
another. Nora then left to play with Beti (a female aged seven and a half years). Janet followed her114 Social behaviour and relationships