Prior research indicates that being reared in stressful environments is associated with earlier onset of menarche in girls. In this research, we examined (a) whether these effects are driven by exposure to certain dimensions of stress (harshness or unpredictability) during the first 5 years of life and (b) whether the negative effects of stress on the timing of menarche are buffered by secure infant-mother attachment. Results revealed that (a) exposure to greater harshness (but not unpredictability) during the first 5 years of life predicted earlier menarche and (b) secure infant-mother attachment buffered girls from this effect of harsh environments. By connecting attachment research to its evolutionary foundations, these results illuminate how environmental stressors and relationships early in life jointly affect pubertal timing.

To illuminate which features of an unpredictable environment early in life best forecast adolescent and adult functioning, data from two longitudinal studies were examined. After decomposing a composite unpredictability construct found to predict later development, results of both studies revealed that paternal transitions predicted outcomes more consistently and strongly than did residential or occupational changes across the first 5 years of a child's life. These results derive from analyses of the NICHD Study of Early Child Care and Youth Development, which included diverse families from 10 different sites in the United States, and from the Minnesota Longitudinal Study of Risk and Adaptation, whose participants came from one site, were disproportionately economically disadvantaged, and were enrolled 15 years earlier than the NICHD Study sample. The finding that results from both studies are consistent with evolutionary, life history thinking regarding the importance of males in children's lives makes this general, cross-study replication noteworthy.