By Published: March 23, 2018

The microbiomes of non-human primates might have more flexibility than previously thought, according to a CU Boulder anthropologist

Social behaviors and microbiome diversity might be interconnected, according to new research by a University of Colorado Boulder anthropologist.

The research finds that lemurs who have more social interaction have less microbiome diversity—and tend to be under stress—while more solitary lemurs have greater diversity in microbiomes. Scientists are probing the question of whether microbiome diversity is generally beneficial.


Steven Leigh

These findings were recently published in the Journal of Animal Ecology.

“What was interesting was that it showed social influence impacting the microbiome directly,” says Steven R. Leigh, professor of anthropology and former dean of the College of Arts and Sciences.

Fecal samples of red-bellied lemurs were collected in Madagascar and analyzed by a transnational team of researchers from Oxford University and the University of Illinois Champaign-Urbana.

In Madagascar, lemurs branched off early in ancient evolutionary history and co-evolved with their environments.

“Primatologists have found that fecal samples are surprisingly informative, far more than we could have ever anticipated,” Leigh states, noting that collecting fecal samples disturbs the animals less than sampling methods involving direct contact. Samples tend to be abundant, and are easy to obtain, analyze, and archive. 

What was interesting was that it showed social influence impacting the microbiome directly."

Data gathered from red-bellied lemurs suggest that those subject to stress are more likely to cuddle and be groomed by their peers. Stress reduces microbiome diversity, and diverse gut bacteria and microbiomes directly impact lemur immune system capabilities.

This study is part of a larger project formed by Leigh analyzes multiple primate species and problem sets. “We have been trying to compare microbiomes across a large number of species.”

Leigh’s overarching project examined 40 to 50 other primate species’ microbiomes thus far, examining behavioral correlations to microbiome diversity and differences from humans.

“One of the really interesting things there is that human microbiomes are very flexible. We do not normally see that flexibility in non-human primates, although this study is showing flexibility based on social interaction.”

Previously microbiomes from human hunter-gatherer groups, non-hunter-gatherer groups and gorillas have been compared by Leigh’s team, consisting of Rob Knight and Katherine Amato, formerly at CU Boulder but now at the University of California San Diego and Northwestern University, respectively. Knight is known as a well-known microbiome researcher.

Comparing different species, Leigh’s work analyzes complex factors leading to microbiome diversity, including social relations, cuddling, grooming, seasonal dietary habits and region of body.

Leigh also notes that technological advancements in sequencing techniques just in the last few years have been remarkable, meaning samples are more productive and yield more data.

Lemurs’ bodies, just like humans, have more microbes than cells. “There are more bacteria, viruses, archaea in us than our own cells,” Leigh states. Bacteria and archaea are two of three major branches on the tree of life.

He adds, “You can’t really ignore a system that is that extensive.”