Everyone loves a good love story, scientists included. I often see news headlines and research articles published on various aspects of what we describe as “love” in the animal kingdom. The sweet story of Denmark’s “gay” King penguins adopting a penguin chick, mated Gibbons singing duets together, and the list continues… So in honor of St. Valentine’s Day, I thought it’d be a good time to highlight one of science’s “famous couples”. Move over Romeo & Juliet, goodbye Elizabeth Bennett and Mr. Darcy— you’ve been overshadowed by the Prairie Vole.
The prairie vole Microtus ochrogaster is a classic example for monogamous mating in the wild. This rodent exhibits long-term pair bonds and high levels of paternal behavior. This partner preference is a fairly unique situation. Remember that in order for a species to survive, they must procreate, and as a male, a great way to make sure that your genes are passed on to future generations is to maximize the number of offspring you produce. Selective affiliations with a single partner and high levels of male parental input have less obvious evolutionary benefits for rodents, compared to this “the more, the merrier” type of male behavior.
There is plenty of speculation on why some animals display monogamy. Its easy to anthropomorphize these situations, and romantic-minded individuals are often disappointed by the results of studies on the topic. In my opinion, its hard to examine what an animal is “feeling”, but you can try to identify some key neurotransmitters and pathways. A really interesting aspect of the research on prairie voles has been the detection of a neural mechanism behind the social attachment in mating pairs. In an article published in Nature in 1993, researchers linked a specific amino acid, vasopressin, to partner preference. Transmission of vasopressin in the male prairie vole brain is essential to forming a social attachment to a mate. They also identified that the distribution of vasopressin receptors in the monogamous prairie vole brain differ from that in polygamous species. Vasopressin is involved in all kinds of social memory and learning in other species, so it makes sense that it plays a key role in prairie vole pair bonding. Of course many caveats to this argument have been discussed, however, this work remains one of the first important findings for the neural basis of monogamous social organization. Its also a terrific Valentine’s Day tale for those less interested in poetry and greeting cards, and more interested in neuroscience research articles.