There is growing evidence that the number and quality of social relationships have substantial impacts on health, well-being, and longevity, and, at least in animals, on reproductive fitness. Although it is widely recognized that these outcomes are mediated by a number of neuropeptides, the roles these play remain debated. We suggest that an overemphasis on one neuropeptide (oxytocin), combined with a failure to distinguish between different social domains, has obscured the complexity involved. We use variation in 33 SNPs for the receptor genes for six well-known social neuropeptides in relation to three separate domains of sociality (social disposition, dyadic relationships, and social networks) to show that three neuropeptides (β-endorphin, oxytocin, and dopamine) play particularly important roles, with each being associated predominantly with a different social domain. However, endorphins and dopamine have a much wider compass than oxytocin (whose effects are confined to romantic/reproductive relationships and often do not survive control for other neuropeptides). In contrast, vasopressin, serotonin, and testosterone play only limited roles.
Keywords: empathy; genetics; romantic relationships; social networks; social neuropeptides.