Research has shown that in conjunction with genetic factors, significant aspects of non-human primate development are influenced by the infant's physical and social environment. In addition to the direct impact of the environment on the infant, the infant's attachment relationship with the mother is seen as the primary mediating factor in shaping these influences. When the mother is able to cope with environmental demands, as a reflection of her responsivity to her infant's needs, she may prepare infants for periodic interuptions in her attention, ameliorate distress during disruptive periods and, most importantly, compensate for these disruptions with enhanced attention to her infant once they are ended. Our recent work shows that when the mother's survival requirements increase, and her coping capacities are exceeded, both short and long-term deleterious effects on her developing offspring may emerge. Particularly when confronted with an unpredictable environment, mothers are less able to maintain effective, stress-buffering, maternal-coping mechanisms which can preserve a stable attachment relationship and permit normal infant development. When these coping mechanisms are insufficient, infants may show manifest disturbances, such as depression, during development or reveal more latent disturbances, such as reduced sociability and timidity, when psychologically challenged, even as young adults. Evidence now suggests that these long-term effects may, at least in part, be the product of altered neurodevelopment of the serotonergic and noradrenergic systems.