the ecosystems in our guts

Yesterday for ScienceNOW I wrote about a study of primate poop. (Heh.) Ok, the fact that it’s about poop is amusing, but it’s also interesting science. The researchers were interested in the makeup of the microbial community in primates; they had fecal samples from some gorillas (of both species), a handful of chimps from each of three subspecies, and two humans, for a total of 26. All of the animals lived in the wild.

The researchers took each poop sample and did some genetic magic to figure out what the different microbial communities looked like – like, what the relative abundance of different species are. Then they compared the communities from different individuals and used those comparisons to group the animals into trees. So, if I have 10 of species A and a million of species B, and you have 12 of species of A and a million of species B, but a gorilla has 10 million of species A and none of species B, you and I will be grouped together and the gorilla will be separate from us.

(I made up these numbers, and the real calculations are more complicated ’cause they involve way more than two species. But anyway.)

This magic produced a tree that looks kind of like a family tree but is a tree of microbial communities. But here’s the thing: It looks just like the primate family tree. Chimps look like each other, humans and chimps look more like each other than gorillas; same is true of our microbial communities.

This is kind of wacky, because there’s no particular reason to think that microbial communities should look similar in closely related species. I mean, we aren’t sharing a lot of bacteria with chimps in our daily lives, and we have pretty different diets. So, kinda funky. And it suggests that diet is less important as a determinant of the gut microbial community than people thought.

Read about it here.

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