Social Chimpanzees Have More Varied Guts

Chimpanzees that are more social have richer and more diverse gut microbiomes than those who are socially isolated, according to research published in the journal Science Advances.

Researchers from the University of Texas at Austin and Duke University analyzed the bacterial DNA found in 40 chimpanzees’ fecal matter between 2000 and 2008 to demonstrate that their interactions propagate microbial diversity in the gut microbiome both within and between the host generations.

The chimpanzees in the study ranged from infants to seniors.

Once the researchers identified the various bacteria living in the animals’ guts, they combined the microbial data with the animals’ dietary records and social patterns.

Many of the gut bacteria the researchers identified were also found in human guts, such as Olsenella and Prevotella.

The researchers noted that the chimps spent more time together during the wet season and spent more time independently during the dry season. This translated to the chimpanzees carrying roughly 20 to 25% more bacterial species during the wet season compared to the dry season.

The gut microbial makeup varied between each particular animal, but the study authors believed the bacteria traveled between the chimpanzees during grooming, mating, or other physical contact periods. Sometimes, the researchers said, bacteria could be spread if the chimpanzees stepped in another chimp’s poop.

The chimpanzees’ diets impacted their gut microbial makeup, but not significantly. The researchers said that some gut bacterial changes were due to seasonal changes in fruit, leaves and insects in their diet, but the social aspects were the most important.

The investigators also learned that the gut bacterial makeup in the chimpanzees boasted similarities regardless of whether or not the chimps were related. They said this finding was particularly surprising, as infants’ first exposures to microbiomes are as they are being born. The researchers suggested that social interactions are just as important as the primary exposure from the mother.

“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 of the University of Texas at Austin said in a press release. “It’s really an amazing and previously underexploited resource.”