A neat new study provides another example of the link between genes and behaviour, and takes the vole oxytocin-vasopressin story (pp. 48-50) a step further. Walum et al (2008) showed that human males with a particular allele of a vasopressin receptor gene (which is expressed in the brain) were less likely to be married, more likely to have a marital crisis, and had marriages which their spouses rated as less satisfactory, than men with no copies of this allele. The researchers didn’t ask whether men with the allele were more likely to be unfaithful, but it’s an obvious follow up. Thus, not only are there genetic effects on pair-bonding behaviour in humans, but they even involve the same proximate mechanisms as they do in that other pair-bonding mammal, the vole. This is what is known as a ‘deep homology’, where the same proximate mechanism gets used for a similar task in phylogenetically quite distant species.

Walum, H. et al. (2008). Genetic variation in the vasopressin receptor 1a gene (AVPR1A) associates with pair-bonding behaviour in humans. Proceedings of the National Academy of Sciences of the USA [DOI: 10.1073/pnas.0803081105]