Adult Content Interest May Be Evolutionary Product, Researchers Say

Conducted by faculty from Duke’s neurobiology department and sponsored by the National Institute of Mental Health, the study examined rhesus macaques and to what lengths they were willing to go to in order to acquire social information.

By using fruit juice as a form of currency and displaying a variety of pictures to the macaques that included images of high-ranking and low-ranking monkeys, as well as images of female monkey posteriors, the researchers found that macaques placed a high value on viewing images of high-ranking monkey faces or female monkey posteriors.

“Decades of studies of monkeys in the wild have indicated that they act as if they make judgments about dominance rankings and the importance of other individuals for their own reproductive success,” said neurobiologist Michael L. Platt. “What we now have with these monkeys is an excellent model for how social motivation for looking is processed in normal individuals.”

According to Platt, male monkeys would often forego a significant amount of physiological necessities such as drink in order to gain visual access to female genitalia, an act which Platt attributes to the monkeys’ need to gain visual social information in order to function properly in society.

While the study does not present definitive links between human and monkey behavior, Platt said that it opens the door for important conclusions regarding human motivations.

“At the moment, it’s only a tantalizing possibility, but we believe that similar processes are at work in these monkeys and in people,” Platt said. “After all, the same kinds of social conditions have been important in primate evolution for both nonhuman primates and humans. So, in further experiments, we also want to try to establish in the same way how people attribute value to acquiring visual information about other individuals.”

Platt also said that the study may include important information relating to how “social machinery” in the brain is affected by autism, which currently afflicts more than a million Americans and is considered the fastest growing developmental disorder.

“One of the main problems in people with autism is that they don’t find it very motivating to look at other individuals,” Platt said. “And even when they do, they can’t seem to assess information about that individual’s importance, intentions or expressions.

“[What we have now is] a model that we can use to explore the neurophysiological mechanism of those motivations in a way we can’t do in humans,” Platt said. “For example, we can use drugs that affect specific neural processes to explore whether we can mimic some of the deficits found in autism in these animals.”