Sex differences in intimate relationships

TL;DR

This study uses mobile phone data to reveal significant sex differences in relationship patterns over the lifespan, highlighting how reproductive investment strategies influence social dynamics.

Contribution

It provides novel insights into how gender-specific reproductive strategies shape relationship dynamics across the human lifespan using large-scale mobile phone data.

Findings

Women show shifting patterns of relationship investment over the lifespan.

Men's relationship patterns are less variable across age.

Reproductive investment influences social relationship preferences.

Abstract

Social networks have turned out to be of fundamental importance both for our understanding human sociality and for the design of digital communication technology. However, social networks are themselves based on dyadic relationships and we have little understanding of the dynamics of close relationships and how these change over time. Evolutionary theory suggests that, even in monogamous mating systems, the pattern of investment in close relationships should vary across the lifespan when post-weaning investment plays an important role in maximising fitness. Mobile phone data sets provide us with a unique window into the structure of relationships and the way these change across the lifespan. We here use data from a large national mobile phone dataset to demonstrate striking sex differences in the pattern in the gender-bias of preferred relationships that reflect the way the reproductive investment strategies of the two sexes change across the lifespan: these differences mainly reflect women's shifting patterns of investment in reproduction and parental care. These results suggest that human social strategies may have more complex dynamics than we have tended to assume and a life-history perspective may be crucial for understanding them.