Monogamy and the Prairie Vole; Battle of the Sexes; Exclusive Online Issues; by C. Sue Carter and Lowell L. Getz; 6 Page(s)

Observation of the mating and pup-rearing habits of nondescript, brown rodents that live under weeds and grasses might not seem an obvious way to improve knowledge of monogamy. After all, most humans can attest to the complexity of male-female relationships. Yet studies of the prairie vole (Microtus ochrogaster), a common pest throughout the midwestern U.S., have led us on a fascinating scientific journey from our starting point in ecology to the exploration of the neuroendocrinology of social bonds. Unlike most rodents, prairie voles form long-lasting pair bonds, and both parents share in raising their young. Our studies have provided a new understanding of the importance of two hormones, oxytocin and vasopressin, which are well known for their respective roles in reproduction and body water regulation. Work with voles now suggests that these hormones are involved in the development of monogamy.

The chief criterion that defines monogamy is a lifelong association between a male and a female. Within this broad definition lie several characteristics that are easily observed. Males and females of monogamous species tend to be about the same in size and appearance. Mated pairs will defend the nest and territory from intruders, and both parents care for the young. Monogamous mammals may form complex social groups that include an extended family and offspring of various ages. Incest is avoided within these families; adult young usually do not reproduce as long as they live with related family members. Finally, we should point out that although common in birds, monogamy is rare in mammals. In an exhaustive survey, Devra G. Kleiman of the National Zoological Park in Washington, D.C., found that only about 3 percent of mammals are monogamous.