Chimps and gorillas can be friends

Interspecific interactions between sympatric apes https://t.co/B69OqvG4U6

— Bill Benzon, BAM! Bootstrapping Artificial Minds (@bbenzon) October 12, 2022

Abstract from article linked above:

Highlights

• First evidence of social relationships between chimpanzees and gorillas is reported
• Social ties between chimpanzees and gorillas persisted over years and across contexts
• Ape species engaged in a wide range of interactions, from play to aggression
• Coexisting great apes may inform us about interactions between some early hominins

Summary

Gorillas reside in sympatry with chimpanzees over the majority of their range. Compiling all known reports of overlap between apes and augmenting these with observations made over twenty years in the Ndoki Forest, we examine the potential predation-related, foraging, and social contexts of interspecific associations between gorillas and chimpanzees. We reveal a greater diversity of interactions than previously recognized, which range from play to lethal aggression. Furthermore, there are indications that interactions between ape species may serve multiple functions. Interactions between gorillas and chimpanzees were most common during foraging activities, but they also overlapped in several other contexts. From a social perspective, we provide evidence of consistent relationships between particular chimpanzee-gorilla dyads. In addition to providing new insights into extant primate community dynamics, the diversity of interactions between apes points to an entirely new field of study in early human origins as early hominins also likely had opportunities to associate. 

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Here's the story as reported in the NYTimes. From the article:

Social apes occasionally stepped on one another’s toes, and the team noted moments of friction. But aggressive interactions rarely got beyond yelled warnings, and never escalated to the kind of lethal interspecies attacks seen at sites in Gabon.

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“They’re not spending all of their time together, but they’re definitely coming together more consistently and regularly than we’d anticipated,” Dr. Sanz said. “These social ties are not what we’d have been expecting if these were just chance interactions in a foraging landscape.”

These sorts of groupings don’t seem to help ward off predation, Dr. Sanz and her colleagues found. Instead, maintaining friendly relationships seems to open up new feeding opportunities, with apes of different species sometimes alerting one another to fruits that are harder to spot. Co-feeding, in turn, gives apes a chance to make lasting relationships.

“Five or 10 years down the road, these individuals on the landscape know each other — they grew up together, they interacted every week or so at different types of food resources,” Dr. Sanz said.

It’s notable that these connections often start with play between two similar species, said Frans de Waal, a primatologist at Emory University who was not involved with the study. “It must be as much fun for them to play together as it is between us and, say, a dog or other companion animal. It expands how we look at primate social systems, which traditionally is entirely within species.”