Ed Yong writes about an examination of the microbiomes of different monkey species in captivity versus wild populations: “Captivity Makes Monkey Microbiomes More Human-Like”.
In the wild, both monkeys host different and distinctive communities of gut microbes. But in captivity, these communities converge, so they become harder to tell apart. Even though doucs and howlers come from different continents and naturally eat different kinds of plants, and even though those specific captive individuals lived in three zoos across three different countries, their gut microbiomes ended up looking very similar. They were closer to each other than to their wild counterparts, and oddly similar to the microbiomes of humans.
Why the changes? Zoo animals often get antibiotics, but Clayton found that even untreated animals had different microbiomes from wild ones. Instead, these changes were most likely due to diet.
This is not too surprising but raises many interesting questions about microbiome evolution. Clearly there is a rapid shift in the microbiome based on dietary environment in primates. How much of this is caused by the colonization of the guts of these primates by microbes from humans (or other captive animals)? How much change can be attributed to selection within the microbiomes of these primates? And what does the pace of colonization by microbes of primate guts imply about the evolutionary dynamics of these microbiomes in wild populations?