While lawsuits demanding that captive chimpanzees have the same rights as “legal persons” have failed, recent research proves that chimpanzees share food in a meaningful way, just like humans do. Whether you’re a man or a male chimp, it seems that the way to any heart is through the stomach, and a good meal is going to create a bond with the female you share your meal with.
Just watch an episode of the British cooking-dating TV reality show, Dinner Date, where three individuals vie to win the heart of the same guest (a stranger) on different nights, and you will identify. As the authors of the new study on how chimpanzees share food state, humans have excellent skills in exchanging cooperatively with individuals who are unrelated to one another.
It’s a trait that is said to be fundamental to the ultimate success of the human species, they explain in the abstract to their paper published on The Royal Society’s Biological Studies website on January 15. There is little understanding about how this behavior evolved or how its mechanisms work. Nevertheless, recognizing that other “social mammals also build long-term cooperative relationships between non-kin,” this idea became the springboard for new research.
The resultant paper titled, “Food sharing is linked to urinary oxytocin levels and bonding in related and unrelated wild chimpanzees,” was written by Roman M. Wittig, Catherine Crockford and several other contributors from the Max Planck Institute for Evolutionary Anthropology that is situated in Leipzig in Germany. Both principal authors have previously written papers concerning chimpanzees and baboons.
The US National Institutes of Health (NIH) describes oxytocin as “a hormone produced by the hypothalamus and stored in the pituitary gland.” Without any doubt it is a very powerful hormone. When we kiss or hug people we love, our oxytocin levels surge. It is also known to act as “a neurotransmitter in the brain,” playing an enormously important role when it comes to two people (or two animals) bonding. It is known to be stimulated during sex, as well as during birth and breastfeeding.
Researchers measured the levels of oxytocin from urine gathered from a group of 26 chimpanzees living in the wild in Budongo Forest, Uganda, both before and after they had shared food together. They also measured the levels of oxytocin found in the urine before and after the chimps had eaten without sharing. In total, they analyzed 79 samples.
They found that “irrespective of previous social bond levels,” these levels were higher after “single food-sharing events” rather than “other types of social feeding.” Levels of urinary oxytocin were also higher after chimps had eaten together than after grooming, which is another very important form of cooperative behavior chimps participate in. In other words, when chimpanzees share food, they bond with other chimps more than when they are cleaning one another by grooming. This is just like human behavior in most parts of the world.
This showed the researchers that food sharing amongst chimps probably plays a key role when it comes to social bonding “under the influence of oxytocin.” Interestingly, it didn’t matter whether the chimps had actually been fed. The important factor was that two of them had been together during the food sharing process. This, it seems, is what makes them bond.
According to Wittig, the increase in the levels of urinary oxytocin had nothing to do with whether or not subjects received food, or gave food to another chimp. It also did not relate to whether they had shared with chimps that were family or those that weren’t. Nor did it matter if there was any type of established bond with the partner, or whether they were sharing meat or some other type of food type.
He believes that sharing food could be key to successful social bonding in chimpanzees, largely because it is of benefit to both the chimp giving the food and the chimp receiving it. It might, he says, even become a trigger and something that is able to predict cooperative relationships.
Another element explored by the researchers was the activation of neurobiological mechanisms known to play a vital role in the bonding between a mother and her child during lactation and breastfeeding.
According to Wittig, it probably produces a bond that continues way past the moment of weaning. It doesn’t stop there either. He believes it might have been “hitch-hiked” and as such is now able to promote the formation of a bond. It probably also plays an important role maintainng “non-kin” or non-family cooperative relationships.
In December three courts in New York rejected claims that chimpanzees had “the same rights as a ‘legal person’.” This was after the Nonhuman Rights Project had filed three suits relating to four chimps they maintained were being unfairly and inhumanely confined. Their aim was to allow the chimps to “live out their days with others of their kind in an environment as close to the wild as is possible in North America.”
While these four chimpanzees have not been the subject of research, they don’t have the opportunity to share food and bond with other chimps. But if it was possible that these chimpanzees could share food in this environment, it’s possible that their urinary oxytocin levels would rise and they’d be a whole lot happier. Ironically it isn’t known whether human oxytocin levels increase after meals have been shared, but certainly when humans share food, they often bond with the person they are sharing it with – just like chimpanzees bond with other chimps.
By Penny Swift