For nine months, Jonathan Clayton, ’15 Ph.D., ’17 D.V.M., spent nearly 15 hours a day tracking red-shanked doucs, an endangered primate species, through Vietnam’s Son Tra Nature Reserve and collecting their ... poop.

Clayton was part of a team that studied doucs in the wild and in captivity to learn about their diet and its effect on their gut microbiota—the organisms that share their intestines. “Doucs do poorly in captivity,” Clayton says. “They develop GI distress and illness.”

His team documented doucs eating 57 plant species in the wild—a diet that’s difficult to replicate in captivity.

“We were trying to get at the question: How much do genetics vs. environment and diet influence the composition of the microbiome?” he says.

Using DNA sequencing to analyze stool samples, they discovered that doucs housed at zoos in Philadelphia and Singapore ate a more limited diet than those in the wild and had lost much of their native gut microbiota. 

“We found that captivity and loss of dietary fiber in primates are associated with loss of native gut microbiota and convergence toward the modern human microbiome,” says Clayton, a recipient of the Van Sloun Family Scholarship and the Walter H. Judd International Fellowship. A high-fat, low-fiber diet has been implicated with changing the human microbiome and promoting obesity and its related illnesses.