Social environments and the genetics of aging: advancing knowledge of protective health mechanisms.

We selectively review the literature in behavioral and molecular genetics, including both laboratory and epidemiologic studies, with emphasis on how social environments, particularly emotion in significant social relationships, influence gene expression. Attention is given to cross-talk between human and animal studies. Environments are pivotal in understanding phenotypic outcomes, and this demands research on gene-environment interactions. Illustrative interactions, involving both behavioral and molecular genetics, are provided. Many people with susceptibility genes for diverse diseases never proceed to disease status. Substantial associational evidence implicates social environmental factors as protective agents. Mechanistic understanding of these linkages is quite advanced in some animal populations and suggests new lines of inquiry in human studies. Developing the interface between genetics, social environments, and health will require close collaboration between those well versed in molecular biology and biochemistry and persons with expertise in genetic epidemiology and social psychology. Particularly important is the identification of environmental influences that protect susceptible persons from disease incidence.