Evolutionary Behavioral Sciences

Relationship Foraging: Does time spent searching predict relationship length?
Cohen SE and Todd PM
Animals foraging for resources often need to alternate between searching for and benefiting from patches of those resources. Here we explore whether such patterns of behavior can usefully be applied to the human search for romantic relationships. Optimal foraging theory suggests that foragers should alter their time spent in patches based on how long they typically spend searching between patches. We test whether human relationship search can be described as a foraging task that fits this OFT prediction. By analyzing a large, demographically representative dataset on marriage and cohabitation timing using survival analysis, we find that the likelihood of a relationship ending per unit time goes down with increased duration of search before that relationship, in accord with the foraging prediction. We consider the possible applications and limits of a foraging perspective on mate search and suggest further directions for study.
The Effect of Paternal and Alloparental Support on the Interbirth Interval Among Contemporary North American Families
Szabó N, Dubas JS, Volling BL and van Aken MAG
The present study investigated whether the length of interbirth intervals between first and second-born children in a North-American middle-class sample could be explained by paternal and alloparental support and firstborn children's gender. The sample consisted of 225 families in which mothers were expecting their second child. Parents reported on paternal and alloparental support (maternal kin, paternal kin, and non-kin support). The results showed that higher maternal kin support and having a firstborn son was linked with shorter interbirth-intervals. Mothers' longer work hours during the pregnancy with the second born was related to longer interbirth intervals. These results highlight the importance of maternal kin support and children's characteristics in understanding the timing of birth when parents have a second child.