Everybody loves a good story about animals being friends. But there’s often a lot more to those heartwarming images than any of us would suspect. That’s certainly the case with chimpanzee buddies. In a paper published today in Science Advances, researchers say that friendly chimpanzees have healthier microbiomes.
The term “microbiome” refers to the microscopic ecosystem of bacteria, fungi, and archaea that live on your skin and in your mouth and gastrointestinal tract. Like any ecosystem, a microbiome is healthiest when it contains a wide range of species. Studies have shown that low microbial diversity is linked to a number of medical conditions. “The more diverse people’s microbiomes are, the more resistant they seem to be to opportunistic infections,” co-author Andrew Moeller said in a press release.
The contents of your microbiome come from a wide variety of sources, including your family, your diet, and the world around you. For social animals like humans and chimpanzees, that world includes a lot of contact with others.
Moeller and his colleagues wondered just how much of an effect socializing could have on the microbiome. To find out, they spent eight years studying wild chimpanzees in Tanzania’s Gombe National Park, collecting chimpanzee poop. The researchers followed 40 individuals, ranging in age from babies to seniors, picking up what the apes left behind while noting what the animals ate and how much time they spent with others.
The scientists then brought the chimpanzee poop back to the lab and sequenced the DNA of all the bacteria inside. They found that the chimps’ microbiomes were about 20 to 25 percent more diverse during the rainy season, a time when bugs, fruit, and leaves are in abundance.
But it wasn’t just the food that was causing those changes. The researchers noted that the chimps spent a lot more time together during the rainy season, mating and grooming one another. And where there were a lot of chimpanzees in close proximity, the odds of one individual accidentally stepping in another’s poop was increased. In short, there was a whole lot of bacterial transmission going on. The friendlier the chimp, the more diverse its gut bacteria.
The study results also showed that the specific bacteria species found in chimpanzee guts were just as likely to be similar between friends as they were between mothers and babies, a fact that suggests that social interactions are far more important than initially believed.
The microbiomes and chimpanzee friendships are especially interesting to scientists because they may offer clues to the evolution of human interactions.
“One of the main reasons that we started studying the microbiomes of chimpanzees was that it allowed us to do studies that have not or cannot be done in humans,” study co-author Howard Ochman said in the press release. “It’s really an amazing and previously underexploited resource.”
More research is needed to find out whether and how the diversity of gut bacteria affects chimpanzee health, and how the findings of this study might translate for humans.