Study: Primates in captivity have lost native gut bacteria

University of Minnesota researchers studied monkeys from St. Paul, Singapore and Vietnam to understand captivity’s influence on gut bacteria.

Melissa Steinken

Studies of monkey fecal matter have recently shown that
captivity hurts the diversity of helpful gut bacteria in primates.

To better understand what captivity does to the gut bacteria
of monkeys, University of Minnesota researchers studied animals from St. Paul’s
Como Park Zoo, a Singaporean wildlife conservatory and wild animals from
Vietnam — using the same methods scientists use to research human diets.

Jonathan Clayton, a University College of Veterinary
Medicine PhD student, sampled the feces of two primate species for the project
— the red shanked douc and mantled howler monkey.

“This is a tool for monitoring that allows us to establish
if wild and captive populations are different,” Clayton said.

The tests showed monkeys in captivity lost most of their
wild gut microbes and acquired less diverse, human bacteria, he said.

These “microbiomes” of gut bacteria help digest food, train
the immune system and protect against pathogens.

Dan Knights, lead advisor on the project, said the microbiomes
may have been disrupted by monkeys eating less plant fiber in captivity.

A low fiber diet is the least alarming explanation, Knights
said, but the change could also be an effect of migration to the West.

“It makes me wonder if the bacteria we think are humans’ are
just really good at competing against the others and are just harder to
displace should we ever want to go back to a primitive setting,” he said.

Monkeys that live in zoos are fed food substitutes —
replacing plants found in their native climates — due to cost, said Dr. Micky
Trent, head veterinarian at Como Park Zoo.

“They don’t thrive well in captivity,” said Tim Johnson, advisor
on the project.

Trent said some vegetarian primates get processed food or
leaf biscuits in lieu of plants.

For his research, Clayton also collected samples from monkeys
at zoos across Southeast Asia, Central America and the U.S.

At Vietnam’s Endangered Primate Rescue Center,  which features semi-captive dwelling,
primates were fed three times a day with a higher level of native plants; the
mammals were left alone during lunch time, giving the red-shanked doucs time to
digest and rest, Clayton said. Doucs have a four-chamber stomach and only eat unripened
fruit, which takes time to digest.

Clayton said he was surprised to find that five of the nine
doucs in captivity died from gastrointestinal-related diseases within a year of
the sample collection.

Johnson said these less-diverse microbiomes could also cause
diseases in humans, like obesity and diabetes.

“It’s also clear in a number of studies we have been
co-evolving our gut bacteria throughout human evolution,” Knights said.

According to the study, results could provide a model for
further understanding effects of modernization and human migration on human diseases
linked to gut bacteria.

“I think just as the way it’s going in the human world, very
similar in the primate world,” Clayton said.

Now, University PhD student Pajau Vangay, is conducting a
study on immigrant populations from around the Twin Cities. She will join
University advisors and West Side Community Health Services to study the
microbiomes of the Hmong and Karen populations in the upcoming year.

 “The primate study
gives us a nonhuman way of looking at microbiomes,” Vangay said. “That gives us
preliminary support of why we’re even doing this immigration study.”