Female chacma baboons (Papio cynocephalus ursinus) in the Drakensberg mount
ains, experiencing neither predation nor within-group competition, structur
e their social relationships with other females in order to sustain recipro
cated grooming (Henzi et al., 1997b). To do so, they cap, where time constr
aints demand, the size of their grooming cliques. From this we have assumed
that the social orientation of mountain baboon females is primarily toward
s other females and that fission is a consequence of the increasing differe
ntiation of cliques, leading to one or a few females following a male 'frie
nd' when he departs. An alternative argument (Barton et nl., 1996) is that,
where predation or within-group competition do not occur, neither should f
emale-bonded groups. In this view, females under such conditions should be
'cross-bonded' to males, each group male associating with a few females in
the manner of hamadryas baboons (P. c. hamadryas). We test this prediction
of 'cross-bonding' at both troop and individual level and find no evidence
to support it. We then present data on fission events which argue for fissi
on in the Drakensberg being due to the departure of small one-male units. H
owever, the data do not support, unequivocally, the proposal that females l
eave with male 'friends'. They do, however, always leave with a male who ha
s fathered at least one of their non-adult offspring.