DEVELOPMENT
OF
SOCIAL RELATIONS
Blue
monkey males and females have
very
different social lives. Females remain in their natal groups
for their entire lives. Males, however, leave the group in
which they were born at puberty to live alone or in
loose associations with other extragroup males; eventually these young
males may find a spot as resident male in a group, or they may compete
for many years as "bachelors". Regardless of where they end up,
however, males have a non-exclusive relationship to the group in which
they reside, and this apparent at all life stages. As juvenlles, they
play with male peers in neighboring groups, and they may visit such
groups for hours as middle to old juveniles; they are also less
involved than same-aged females in the aggressive territorial fights
that punctuate blue monkey group life. Males living in groups as adults
do not limit their
social
interactions to groupmates: while the females defend the group’s
territorial
boundaries, males are likely to use intergroup contests as
opportunities to mate
with
neighboring females (and they do sire neighboring offspring). A
male’s association with a
group
is thus a rather ephemeral and non-exclusive arrangement.
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, 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. Our paper in the American Journal of Primatology summarized the results as follows:
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.
Nicole Thompson is using direct measures of fitness in juveniles to investigate these (and related) ideas further.
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, 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. Our paper in the American Journal of Primatology summarized the results as follows:
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.
Nicole Thompson is using direct measures of fitness in juveniles to investigate these (and related) ideas further.