With the New Year comes resolutions to eat better, make a career change or to just be a better friend. With a high volume of birthdays approaching in the coming months, the thought of getting something for your roommate or distant friend may cross your mind, especially since you are subliminally expecting something from them. People may deny such thoughts and claim that it is all out of the goodness of their heart but studies using primates as models say otherwise.
Adrian Jaeggi, a postdoctoral researcher in anthropology at UC Santa Barbara and a junior research fellow at the campus’ SAGE Center for the Study of the Mind, conducted a study to answer the question of reciprocity — resource exchange between individuals — using chimpanzees and bonobos as his subjects.
“Many primates exchange grooming, social support or even food sharing on a reciprocal basis. Most of this reciprocity happens in the long-term fashion … the evidence for immediate exchanges is much more limited,” Jaeggi said. “This suggests that single events are negligible, and primates balance exchange over longer time frames; they have ‘friendships.’ The function of friendships is to ultimately increase reproductive success by helping the individual to have more surviving offspring.”
The researchers gave food to certain individuals in the chimpanzee and bonobo groups and then observed the success rate of other individuals depending on whether they groomed that individual prior to receiving food as a gift. The chimp group demonstrated a lot of long-term exchange rather than immediate reciprocation. Chimps have long life spans and stable social groups, thus more lasting relationships form between individuals. Because of these friendships, chimps generally shared food with their partners and friends regardless of grooming. Bonobos, however, presented a different result. The bonobo monkeys were much more likely to groom before taking food.
Jaeggi said that bonobos participated in more grooming behavior because they sought the calming effects of the endorphins.
“And there we did see an effect of grooming on sharing,” Jaeggi said in the initial press release. “Chimps would go and take food pretty confidently, but bonobos were more reticent. They’d reach out and then groom. It seemed to be that they’d groom to release tension, and then there would be these short-term reciprocal exchanges.”
As far as what these findings say about humans, they reveal clues about the distant past and why favor exchange has evolved within our society.
“[This study] suggests that friendships are an evolutionarily old feature, going back at least to our last common ancestors with chimpanzees and bonobos … Food is shared between families in order to buffer the risk of coming home empty-handed,” Jaeggi said. “This research indicates that this precondition of reciprocal relationships was already present in our last common ancestor and might have facilitated the evolution of a hunting and gathering lifestyle.”
Chris Swanson, a fourth-year anthropology student at UC Davis, commented on how Native American tribes used gift exchange as a demonstration of wealth. The tradition, known as potlatch, was reciprocated in a grander fashion by the receiving tribe and the cycle started over again.
“The potlatch was a way for leaders to strengthen their social position,” Swanson said.
Studies done on reciprocity are also related to altruism in humans. Altruism, as defined by psychology, is a motivational state with the goal of benefiting someone else’s welfare — though there is a lot of debate among and within the fields concerned with human behavior about what the underlying motive actually is.
“[We] have shown that where monetary rewards are concerned, roughly 20 percent of college students behave altruistically,” said Edmund Fantino, a professor of psychology at UCSD. “[That is] being willing to give up resources in order to give a windfall to an unknown other.”
Whether or not you are fully aware of the subconscious reasoning for why you give gifts, looking at our gift-giving behavior in our closest ancestors has given us detailed insight into the psychology and evolutionary behavior of humans. The practice of giving a cup of sugar to your neighbor may yield more than just a cup of sugar in return.
NICOLE NOGA can be reached at science@theaggie.org.
