  Age and gender are two important factors that play crucial roles in the way
organisms allocate their social effort. In this study, we analyse a large
mobile phone dataset to explore the way lifehistory influences human sociality
and the way social networks are structured. Our results indicate that these
aspects of human behaviour are strongly related to the age and gender such that
younger individuals have more contacts and, among them, males more than
females. However, the rate of decrease in the number of contacts with age
differs between males and females, such that there is a reversal in the number
of contacts around the late 30s. We suggest that this pattern can be attributed
to the difference in reproductive investments that are made by the two sexes.
We analyse the inequality in social investment patterns and suggest that the
age and gender-related differences that we find reflect the constraints imposed
by reproduction in a context where time (a form of social capital) is limited.
