DEVELOPMENT
OF
SOCIAL RELATIONS
 A nursing female is groomed by two juveniles |
Blue
monkey males and females have
very
different life histories. Females remain in their natal groups
for their entire lives. Males, however, leave the group in
which they were born just before puberty, and thereafter live alone, in
loose associations with other extragroup males, or they join one (or
maybe more) groups.
Even when they live in groups as adults, males do not limit their
social
interactions with groupmates: while females defend the group’s
territorial
boundaries, males are likely to be looking for opportunities to mate
with
females from the neighboring group. A male’s association with a
group
is thus a rather ephemeral and non-exclusive arrangement.
Interestingly,
differences in the
social lives of immatures seem to
predict these sex differences among adults. Steffen Foerster’s work showed that
during the first half year of life, mother-daughter grooming
increasingly exceeds mother-son grooming. As juveniles, females
have a more diverse set of social partners within their group, whereas
only males play with peers from neighboring groups. These
observations suggest that young females are already cementing bonds
with groupmates more than young males do. Indeed, Stefan Ekernas's work on dispersal-aged
individuals suggests that one reason males leave is that they are far
less socially connected than female peers.
Together
with Stefan Ekernas and Mike Sheehan (University of Michigan), we also
investigated how sex differences develop during the
early-middle part of the juvenile period, starting at the age of 3
yrs. We found marked similarities to adults within each sex.
In addition, in contrast to other cercopithecines living in more
hierarchically organized societies, we found little evidence that blue
monkey juveniles focus their social attention on others according to
their relative dominance rank. Here's a summary of our paper, to
appear shortly in the American Journal of Primatology:
Primates usually lead very different lives depending on their sex. In most Old World monkeys, males leave the group where they were born at puberty, while females stay in the same group their whole lives. Thus males leave behind most of their juvenile social partners, while female juveniles begin building social ties with other females that will last a lifetime. One would expect juvenile primates to choose social partners strategically, females socializing most with other females, males socializing most with male peers with whom they may emigrate later. Preferences should change as animals age, and both males and females should favor socializing with group-mates that provide the best rewards for the least risk. In species where dominance hierarchies play an important role in social dynamics, juveniles usually favor socializing with high-ranking individuals, who may facilitate access to food and provide better defense against aggressive group-mates. But what about species where dominance is unimportant? We studied blue monkeys – in which males leave their natal group, females stay their entire lives, and dominance hierarchies are muted – to see how juvenile social preferences vary with age and sex. Juvenile blue monkeys behaved strategically, favoring socializing with individuals that were likely to remain important partners later in life, avoiding risky partners that were least likely to tolerate them, and changing social preferences as they approached adulthood. Juveniles appear to balance preparing themselves for adult life with minimizing risks during a life stage when they are particularly vulnerable to both predators and members of their own species.
Primates usually lead very different lives depending on their sex. In most Old World monkeys, males leave the group where they were born at puberty, while females stay in the same group their whole lives. Thus males leave behind most of their juvenile social partners, while female juveniles begin building social ties with other females that will last a lifetime. One would expect juvenile primates to choose social partners strategically, females socializing most with other females, males socializing most with male peers with whom they may emigrate later. Preferences should change as animals age, and both males and females should favor socializing with group-mates that provide the best rewards for the least risk. In species where dominance hierarchies play an important role in social dynamics, juveniles usually favor socializing with high-ranking individuals, who may facilitate access to food and provide better defense against aggressive group-mates. But what about species where dominance is unimportant? We studied blue monkeys – in which males leave their natal group, females stay their entire lives, and dominance hierarchies are muted – to see how juvenile social preferences vary with age and sex. Juvenile blue monkeys behaved strategically, favoring socializing with individuals that were likely to remain important partners later in life, avoiding risky partners that were least likely to tolerate them, and changing social preferences as they approached adulthood. Juveniles appear to balance preparing themselves for adult life with minimizing risks during a life stage when they are particularly vulnerable to both predators and members of their own species.