Prairie voles (Microtus ochrogaster) are social and monogamous in the wild, forming life-long pair bonds, a trait shared with only 5% of mammalian species (Young et al., 1998). Many of these behavioral characteristics can also be studied in the laboratory. In contrast to a promiscuous and asocial vole species, montane voles (Microtus montanus), when studied in triads of one male and two females in a laboratory, male prairie voles huddle with one female selectively after mating with her. The behaviors were shown not to be a function of mate availability or female receptivity, but seem to represent a high degree of affiliative behavior (Shapiro and Dewsbury, 1990). Much of this research has been devoted to defining the neuroendocrine correlates of pair bonding, which predominantly feature signaling differences in arginine vasopressin (especially in the vasopressin 1a receptor) and oxytocin systems (Insel, 2003). Interestingly, one recent study suggested that polymorphisms in the human AVPR1A receptor gene were associated with pair bonding in humans (Walum et al., 2008). Some studies have also examined paternal care, male other aspects of social behavior, and various aspects of agonistic behavior (Young et al., 1998).
