Research from the University of Portsmouth suggests that appearing stressed may help people to avoid conflict. The experts found that monkeys often scratch as a stress behavior, and that this action noticeably reduces aggression from other animals.
The study, published in Scientific Reports, raises the question of whether human scratching and similar stress behaviors serve the same purpose.
“Observable stress behaviors could have evolved as a way of reducing aggression in socially complex species of primates,” explained lead author Jamie Whitehouse. “Showing others you are stressed could benefit both the scratcher and those watching, because both parties can then avoid conflict.”
On the 35-acre island of Cayo Santiago, Puerto Rico, the research team observed 45 rhesus macaques from a group of 200. The team monitored the animals’ social interactions for eight months.
The experts discovered that scratching often occurred in times of heightened stress for the monkeys, like when they were in close proximity to strangers or high-ranking individuals. The researchers also noted that the likelihood of a monkey being attacked was significantly lowered by scratching.
For example, the 75 percent chance that a higher ranking monkey would show aggression to a lower ranking monkey dropped to 50 percent if the lower monkey began scratching. The behavior of scratching also lowered the chances of aggression between monkeys that did not have a strong social bond.
“As scratching can be a sign of social stress, potential attackers might be avoiding attacking obviously stressed individuals because such individuals could behave unpredictably or be weakened by their stress, meaning an attack could be either risky or unnecessary,” said Whitehouse.
The researchers believe their work will lead to a better understanding of stress in both humans and animals. The study is the first to suggest that stress behaviors may be responded to by others and also that these behaviors may help to support social cohesion.
“By revealing stress to others, we are helping them predict what we might do, so the situation becomes more transparent,” explained Whitehouse. “Transparency ultimately reduces the need for conflict, which benefits everyone and promotes a more socially cohesive group.”
By Chrissy Sexton, Earth.com Staff Writer