Epigenetics and the Transgenerational Impact of the Social Environment
Frances Champagne, Columbia University, New York, USA
Development occurs within a social context. The critical role of the social environment in shaping our brain and behavior has long been inferred from the association between early social deprivation (in the form of infant neglect or abuse) and adverse neurodevelopmental outcomes associated with increased risk of psychiatric illness. A critical question raised by these findings is regarding the biological pathways through which environmental effects are achieved: What are the mechanisms through which social experiences lead to long-term individual differences in physiology, neurobiology, and behavior? Recent evidence from studies in rodents has implicated molecular pathways involved in the regulation of gene expression as one possible route through which these long-term outcomes are achieved. Factors that influence gene activity without modifying DNA sequence is a feature of the emerging field of epigenetics (meaning “over” or “above” genetics) and may provide insight into the dynamic interplay between genomes and the environment. Epigenetic effects, though not exclusive to social experiences, may be a mechanism through which the quality of the social environment becomes embedded at a biological level. Thus, there is evidence from a variety of experimental models suggesting that mother-infant interactions, social contact with peers, and adult social stress may lead to long-term epigenetic changes in the brain with consequences for stress responsivity, cognition, and social/reproductive behavior. Interestingly, epigenetic variation, much like genetic variation, can be heritable. There is increasing evidence for the transgenerational impact of early experiences mediated either through changes in social and reproductive behavior exhibited in adulthood or through germline epigenetic variation. The role of epigenetics in mediating developmental plasticity both within and across generations provides a novel framework for understanding the inheritance of individual variations in brain and behavior and the role of the environment in inducing heritable modifications. This research has lead to a revival of Lamarckian concepts of the inheritance of acquired traits and highlights the adaptive value of environmentally-induced changes in the activity of genes.
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