Study links captivity and low dietary fiber in nonhuman primates with loss of microbial diversity.
Time spent in captivity causes primate gut microbe communities to begin to resemble those of humans, according to a new study published in the Proceedings of the National Academy of Sciences.
A group of researchers followed around endangered wild red-shanked doucs in the jungles of Vietnam and wild mantled howling monkeys in Costa Rica, collecting gut microbe-laden fecal samples whenever they were lucky enough to spot them. For comparison, stool samples were also obtained from the monkeys’ captive counterparts living in several zoos across three continents.
A diverse array of microbial species — identified through genetic sequencing — inhabited the guts of the wild monkeys. These microorganisms carry out a slew of key functions, including breaking down food and shaping the immune system.
But much of that microbial diversity had been lost from the monkeys confined to captivity, whose guts mainly contained two types of microbes — the same two, it turns out, that dominate the guts of humans.
After ruling out factors like geography, individual genetic makeup, and past use of antibiotics, the researchers pinpointed the most likely explanation for why the captive primate gut microbes were converging toward those of humans: they weren’t eating enough different types of plants.
Interestingly, when the researchers collected fecal samples from sanctuary-living red-shanked doucs, who are fed more plant types than zoo-living monkeys but fewer than the ones living in the wild, their gut microbe diversity fell right between the wild and captive guts. The researchers also found that stool from the wild primates contained significantly greater quantities of plant DNA than that of captive primates.
Sifting through the human data, it became clear that the way that captivity affected the primate gut microbiome paralleled the effects of Westernization on the human gut. The study authors conclude “loss of dietary fiber may be driving loss of core microbial biodiversity in humans and captive primates alike.”
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