Most wild Chimpanzees will expend effort to assist others without return, and also put within-group conflicts aside when they sense a threat, two simultaneously published papers reveal. One of the studies also shows kindness levels vary between chimpanzee groups.
Among our great ape cousins, chimpanzees often seem like the bad members of the family. Orangutans are peaceful introverts, bonobos are lovers not fighters and even gorillas are much gentler than their fearsome reputations might suggest. Chimpanzees, on the other hand, are capable of cruelty that reminds us of our own capacity for atrocities. However, new research shows chimps' also have better sides.
Dr Edwin van Leeuwen of the University of St Andrews installed a juice fountain at a chimpanzee sanctuary in Zambia, with a button to activate it at such a distance that the ape doing the pressing could not drink. When the fountain was fenced that no chimpanzee could reach it, some of the chimps pressed the button occasionally, perhaps out of curiosity. However, their activity increased dramatically when other chimps had access to the juice. Moreover, the apes spent more time pressing the button as the experiment went on, but only when others could benefit.
In Science Advances van Leeuwen and co-authors report major differences between three chimpanzee groups who got to participate in the experiment. Members of one group spent a lot of time in giving others the sweet refreshment, while another group contributed almost nothing to their pack-mates welfare, with the third in between. A fourth group never learned how to press the button at all, and were eliminated from the study for stupidity.
Although the smallest group helped each other the most, the largest one came second, undermining the idea animals are more likely to care for each other in smaller, more closely related, packs. Instead it seems kindness is a culturally transmitted feature possessed more by some chimpanzee populations than others.
Magic juice fountains aside, conditions at the sanctuary are closer to chimpanzees' natural habitat than a laboratory or zoo, so this should offer real insight into wild chimpanzees behavior.
The question of whether chimpanzees are “pro-social”, (will help each other without getting anything in return) has been greatly debated. There have been many reports of chimpanzees selflessly assisting each other, for example by passing on tools, and even aiding researchers. Nevertheless, studies on whether caged chimps will get food delivered to other cages led to the conclusion; “chimpanzees are indifferent to the welfare of others”.
The debate is considered important for shedding light on the origins of humanity's capacity for altruism.
In another study University of Kyoto masters student James Brooks found that playing chimpanzees the sounds of chimps outside their group produced signs of stress not seen when crow calls were played instead. Rather than taking this anxiety out on each other, however, Brooks reports in PLOS One, the apes moved to be physically closer and fought among themselves less, even when insufficient food was available. Those hearing the calls of strange chimpanzees also played more at feeding time and initially groomed each other more - perhaps indicating they knew that if it came to a fight, their family would need to stick together.
"Despite the importance of understanding how humans can be cooperative with their in-group and still carry out acts of extreme out-group aggression, there has so far been little study on whether the association between these behaviors holds in non-human primates,” Brooks said in a statement.
The researchers are now conducting similar studies on bonobos, who, unlike chimpanzees, have little to fear from non-troop members of their own species.