Genetic aspects of mother-offspring conflict in rhesus macaques

This study investigated the occurrence of mother-offspring conflict in rhesus macaques and possible genetic correlations between maternal and offspring conflict-related behavior, using a cross-fostering procedure and a developmental approach. Ten female infants were cross-fostered at birth and observed with their foster mothers during their 1st year of life. Data on the infants' biological mothers were also available. In the 1st 3 months of infant life, there was little or no mother-infant conflict over time spent in contact. Correlations between infant behavior and the behavior of foster mothers in this period likely resulted from individual differences in infant activity levels and maternal concerns for safety or maternal attempts to encourage infant independence. During the mating season, when infants were 7-9 months old, conflict over time spent in contact became apparent. Infant conflict-related behavior was not predicted by their foster mothers' behavior but by the behavior of their biological mothers. These findings concur with those of recent studies in other animal taxa in suggesting that conflict-related behavioral traits may be genetically correlated in mothers and offspring and that the latter may be engaged in a runaway selection process that would result in the escalation of conflict.