Genetic and environmental factors in the intergenerational transmission of maternal care in rhesus macaques: Preliminary findings.

Early life experiences reorganize the brain and behavior of the developing infant, often with lifelong consequences. There is perhaps no more potent developmental influence than the quality of parental care: it is an experience common to all mammals, and its effects have been observed across species. The effects of parental care can be particularly difficult to abolish, as levels of care are often perpetuated across generations. However, genetic relatedness between parents can obscure the true mechanism of transgenerational cycles of parental care, because in intact families, genes, and environment are confounded. We examined the transmission of maternal care quality in biologically reared (n = 21) and cross fostered (n = 6) female rhesus monkeys. Interactions between female infant subjects and their mothers were observed from subjects' birth to 12 weeks of age. Females were then observed 4-5 years later for the quality of care they displayed toward their own newborn offspring. Maternal protectiveness in the first and second generations were correlated in both biologically reared and cross-fostered females. However, other aspects of maternal care, such as aggressiveness and sensitivity, were transmitted differently depending on foster status. These data provide preliminary findings in a small sample that the intergenerational transmission of maternal care may arise from complex genetic and environmental mechanisms in rhesus monkeys.