Early in the movie “Planet of the Apes,” human astronaut George Taylor is shot in the throat by gorillas, but his life is saved by two chimpanzee doctors: Dr. Zira and Dr. Galen. That simple act reveals that the apes have crossed the traditional ‘line in the sand’ separating humans from animals – empathy … which they demonstrate by their prosocial occupations as doctors who voluntarily treat the ailments of others of their species. While apes and monkeys have shown actions that appear to demonstrate treating their own wounds or gastric ailments, they’ve never been seen attempting to heal others … until now.
"In 2019, I was following a female chimpanzee named Suzee, and watched as she tended to the injured foot of her adolescent son, Sia. I noticed that she appeared to have something between her lips that she then applied to the wound on Sia’s foot. Later that evening, I re-watched my videos and saw that Suzee had first reached out to catch something which she put between her lips and then directly onto the open wound on Sia’s foot.”
In a study published in the journal Current Biology, Alessandra Mascaro, a volunteer at the Ozouga Chimpanzee Project in Gabon, West Africa, describes the shocking scenario she witnessed of a mother chimp treating a wound on her adolescent son’s foot with a chewed insect. It’s fortunate she was able to record the event because her superiors have been watching this group of chimpanzees for 7 years and had never seen anything like this. In fact, no one has.
While they had observed many instances of self-medication with chewed insects, Simone Pika, a cognitive biologist at Osnabrück University and Mascaro’s supervisor, says this was the first example of prosocial behavior in chimps. Even more shocking – it was far from the only one. A week after Mascaro observed it, PhD student Lara Southern watch an adult male named Freddy do it again. Over the course of 15 months, they witnessed 22 events of chimps treating their own wound or on another individual with masticated bugs. Then Southern observed a new twist.
“An adult male, Littlegrey, had a deep open wound on his shin and Carol, an adult female, who had been grooming him, suddenly reached out to catch an insect. What struck me most was that she handed it to Littlegrey, he applied it to his wound and subsequently Carol and two other adult chimpanzees also touched the wound and moved the insect on it. The three unrelated chimpanzees seemed to perform these behaviours solely for the benefit of their group member.”
This was not just treatment -- this was nursing care, post-op and therapy by a group of chimps towards a non-related sick individual – it doesn’t get more prosocial or empathetic than that. Behavior like this has rarely been seen in non-humans and this group provides an on-going operating theater for humans to observe chimp medical treatments and recovery. While the psychologists will watch the chimps to track who gives and who receives the ‘treatments’ and how this knowledge and empathy is passed on to others, the biologists hope to sample the chewed insects to determine what gives them the healing power that so many chimps know about and use. Finally, they hope to branch out to other chimp groups to see if this is localized behavior or if empathy can now be ascribed to all chimps.
If chimps are prosocial, what about gorillas? Monkeys?
Have they crossed a line into the Planet of the Apes?