From endophenotypes to evolution: social attachment, sexual fidelity and the avpr1a locus

Both medical and evolutionary genetics increasingly emphasize the importance of subtle, quantitative measures of phenotype. One such ‘endophenotype,’ the distribution of vasopressin 1a receptor (V1aR), is a recent focus for studies of social behavior. In animal studies, the neural distribution of V1aR has been linked to both social attachment and patterns of sexual fidelity. At a genetic level, a microsatellite in the cis-regulatory region of the avpr1a locus has been linked to variation in both brain and behavior. Both sets of data become more complex as the mechanistic and evolutionary details are examined more fully. I briefly summarize recent work from animal and human studies of avpr1a and highlight parallels between comparative and clinical approaches.