Shyness May Be in the Genes

Rodent study suggests 'junk DNA' influences behavior

THURSDAY, June 9, 2005 (HealthDay News) -- Shy? Uncomfortable at parties? Short "junk" DNA may be to blame.

A new animal study suggests differences in the length of seemingly nonfunctional DNA -- known as microsatellite, or junk, DNA -- may explain why some people are outgoing and others tend to be wallflowers. The findings may also help scientists better understand human social behavior, including disorders such as autism.

The study, conducted by investigators at the Yerkes National Primate Research Center of Emory University and the Center for Behavioral Neuroscience (CBN) in Atlanta, appears in the current issue of the journal Science.

The researchers bred two groups of prairie voles -- a type of rodent -- with short and long versions of junk DNA and compared the male offspring after they matured. They found the length of junk DNA affected gene expression patterns in the brain.

Male prairie voles with long junk DNA had higher levels of vasopressin receptors in brain areas involved in social behavior and parental care. Previous research showed that the vasopressin receptor gene regulates social behavior in many species.

Males with long junk DNA approached strangers more quickly, spent more time investigating social odors, were more likely to form bonds with mates. They also spent more time nurturing their offspring than males with short junk DNA.

"This is the first study to demonstrate a link between microsatellite length, gene expression patterns in the brain and social behavior across several species," CBN researcher Larry J. Young said in a prepared statement.

Co-researcher Elizabeth Hammock, a former CBN graduate student, agreed that variance in microsatellite DNA may have a real impact on personality traits. "For example, it may help explain why some people are naturally gregarious while others are shy," she said in a prepared statement.

More information

The Ambulatory Pediatric Association explains social development in children.

SOURCE: Emory University Health Sciences Center, news release, June 9, 2005
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