A series of elegant experiments done on meadow voles versus prairie voles (promiscuous versus monogamous males) show that the different behaviors correlate with genetic variation in the gene for a vasopressin receptor (V1aR). Nonmonogamous meadow voles become more monogamous when V1aR density is increased in relevant brain areas by using viral vector gene transfer. As you might suspect, a similar genetic variation has now been shown by Walum et al.(open access) to correlate with pair-bonding behavior in human males. (I would be most curious to know whether I have the repeat polymorphism that would correlate with my wandering ways!) Here is their abstract:
Pair-bonding has been suggested to be a critical factor in the evolutionary development of the social brain. The brain neuropeptide arginine vasopressin (AVP) exerts an important influence on pair-bonding behavior in voles. There is a strong association between a polymorphic repeat sequence in the 5′ flanking region of the gene (avpr1a) encoding one of the AVP receptor subtypes (V1aR), and proneness for monogamous behavior in males of this species. It is not yet known whether similar mechanisms are important also for human pair-bonding. Here, we report an association between one of the human AVPR1A repeat polymorphisms (RS3) and traits reflecting pair-bonding behavior in men, including partner bonding, perceived marital problems, and marital status, and show that the RS3 genotype of the males also affects marital quality as perceived by their spouses. These results suggest an association between a single gene and pair-bonding behavior in humans, and indicate that the well characterized influence of AVP on pair-bonding in voles may be of relevance also for humans.