Dr. Grossi's Blog

Biology of Faithfullness?

Dr. Philip Grossi
Thursday, 02 September 2010

The genus Microtus contains a variety of species of voles who show an extraordinary range of social differences.  Male prairie voles form lifelong attachments, share duties in raising offspring and manifest high levels of social interest.  The closely related mountain voles do not bond with a mate, do not assist in caring for the offspring, and are socially indifferent.  The pattern of vasopressin 1a receptor (V1aR) in the brains of these animals is thought to be largely responsible.  The expression is the result of differences in the microsatellite regulatory region with the prosocial prairie vole manifesting several repeating blocks interspersed with non-repetitive blocks while the asocial montane vole has a short version.  This results in the brains of prairie voles making more vasopressin receptors than the montane voles do.  This connection was strengthened with their work last year in which they added microsatellites in the regulatory region avpr1a in the montane vole and this resulted in behavior more like the prairie vole.  This further strengthens the tie between male social behavior in the vole to vasopressin.

Hammock and Young went further in this paper.  They paired and then bred voles with long microsatellites and recorded the results, which included the finding that significant genotype difference resulted in significant increased grooming and pup licking in long-allele males when compared to short allele males but no difference in females relative to pup licking and grooming.  They also placed males in cages with females for 18 hours and found that those males with longer microsatellites spent more time with their partner than those with shorter microsatellites.

illustration to biology faithfulness blog

They also compared the microsatellite base length in chimpanzees, bonobos, and humans.  The chimps who are more aggressive than the bonobos had a base length that was 360 bases shorter than the bonobo who are more social and form social bonds similar to humans.  The bonobo microsatellite has a high homology with the human microsatellite.

Are we more patterned than we usually assume?