Scientists look at genetic link for sociability

Recent studies conducted on voles by the Yerkes National Primate Research Center at Emory University and the Atlanta-based Center for Behavioral Neuroscience indicate that certain genetic material once thought to be relatively inert actually contributes to how the animals function as parents and in a social group.

The study centered around microsatellites, which are short, identical DNA sequences scattered throughout genomes (the genetic code of a species) and that can be repeated thousands of times. Earlier, scientists thought the microsatellites were simply filler, or "junk," in an animal's genome. The researchers, however, discovered that the more microsatellites a species has, the more likely it was to show empathy and care-giving behavior.

Humans, voles and bonobos (pygmy chimps known for strong social bonds) have fairly lengthy microsatellite regions, and the three species as a whole tend to be somewhat sociable. Chimpanzees, which are low on the empathy scale, don't have many microsatellites in their genome. (Genome studies focus on species, so it is possible to have individual chimps with longer microsatellites than normal.)

The differences in microsatellites, which can show up by mutation over only a few generations, appear to directly affect how, when and where the protein receptor for the hormone vasopressin presents itself in the brain, the researchers said. Vaspressin is known to aid in the formation of memories. Conceivably, random mutations of microsatellite regions may represent unique opportunities for the expression of genetic adaptations that lead to behavioral diversity in a species.