Effects of early developmental stress on adult physiology and behavior

Events during early development can have long-term effects on physiology and behavior. While extreme developmental stress is known to be associated with a variety of behavioral problems, it is less well understood how milder stress may affect behavior, personality, and reproductive success. This research project assessed a variety of behavioral dimensions in a college age sample, while assessing early development using size at birth, fluctuating asymmetry, and retrospective surveys. Maternal stress during pregnancy was found to reduce adolescent growth spurts and adult handgrip strength in the offspring. In males, lower birth weights were associated with higher scores of impulsivity and inattention, and higher, more feminine, digit ratios. In females, higher scores of impulsivity and inattention were associated with an increased number of sexual partners. More impulsive women also had lower levels of fluctuating asymmetry. Men with large adult bodies and strong handgrips tended to score higher in schizotypy and report more sexual partners. A significant interaction was found between size and schizotypy in predicting number of sexual partners. Men with large bodies, big heads, and strong handgrips who also scored high in schizotypy tended to report a particularly high number of sexual partners. These results confirm that early development can significantly affect physiology and behavior even when levels of stress or under-nutrition are relatively mild. Adult sexual behaviors and attitudes can be affected by these early changes in ways that may enhance or hinder reproductive fitness. This study also identifies adult morphology as playing a critical role in the relationship between schizotypy and reproductive success in men.