A new study suggests it takes only 20 seconds of observation to detect whether a total stranger is genetically wired to display prosocial behavior consistent with empathy, compassion and trustworthiness. The study appears in the 14 November issue of the Proceedings of the National Academy of Sciences (PNAS).

When you go on courses in counselling skills, one of the first things you learn is how to display empathy: how to sit facing the person you are helping in an open position, how to use gestures like nodding and eye contact to signal acknowledgement and understanding, and also how to make reassuring sounds without interrupting the flow of their talk. You can learn to do this: but now it seems scientists have discovered a gene that indicates which people are naturally predisposed to displaying these behaviors.

For the study, lead author Aleksandr Kogan, now a postdoctoral student at the University of Toronto at Mississauga in Canada, and colleagues, filmed 23 romantic couples in one-to-one conversations with one another. In each film, one of the pair was describing to the other a time of suffering in their lives. The other, the "listener", was the subject of observation.

Among other things, the researchers were interested in assessing how "prosocial" the listeners were: they defined prosocial as ability to behave in a way that benefits another person.

116 strangers, unknown to the couples, were then invited to view the video films and rate each "listener" on traits such as how kind, trustworthy and caring they thought they were. The observation lasted only 20 seconds with no sound, so all that could be observed were the subjects' body language and facial expressions as they listened to their partner talking about their suffering.

Before taking part in the filming, the subjects had given blood samples that allowed the scientists to determine their genotype as GG, AG or AA for the oxytocin receptor. A genotype of GG means a person has two copies of G version of the gene (one from the biological mother and one from the biological father).

Widely known as the "cuddle" or "love" hormone, oxytocin is a peptide produced by the hypothalamus in the brain and secreted into the bloodstream. It has targets or receptors all over the body and also within the brain and plays a key role in female reproduction. It has also been linked to trust, love, bonding, reducing the impact of negative responses, and social recognition.

A previous study, carried out at the University of California (UC) Berkeley, where Kogan was based while working on the current study, had looked at these three combinations of the oxytocin receptors and found that people who were most able to interpret others' emotions, who showed the most empathic ability, had the GG combination, while those with AA and AG combinations were less able to put themselves in the shoes of others and also were more likely to become stressed under pressure.

That study was conducted by Sarina Rodrigues Saturn, an assistant professor of psychology at Oregon State University. Saturn is the senior author of the current study.

In the current study, Kogan, Saturn and colleagues found that listeners carrying GG versions of the oxytocin receptor gene were rated as more prosocial than those carrying AG or AA versions.

"People can't see genes, so there has to be something going on that is signaling these genetic differences to the strangers," Kogan told the press. "What we found is that the people who had two copies of the G version displayed more trustworthy behaviors - more head nods, more eye contact, more smiling, more open body posture. And it was these behaviors that signaled kindness to the strangers."

Kogan was keen to point out that having the AA or AG instead of the GG genotype does not mark a person as unsympathetic.

"What ultimately makes us kind and cooperative is a mixture of numerous genetic and non-genetic factors. No one gene is doing the trick. Instead, each of these many forces is a thread pulling a person in one direction or another, and the oxytocin receptor gene is one of these threads," said Kogan.

In other words, some might have these behaviors built in, while others can acquire them. But perhaps we all need awareness of our strengths and limitations and be receptive to feedback in order to deploy the skills we have, whether pre-wired or acquired, to best effect.

Written by Catharine Paddock PhD