Some Microbes Have Been With Us Since Before We Existed

Jul 25, 2016

By Ed Yong

Around 10 million years ago, a population of African apes diverged down two paths. One lineage gave rise to gorillas. The other eventually split again, producing one branch that led to humans and another that forked into chimpanzees and bonobos. This is the story of our recent evolutionary past. It’s also the story of some of the microbes in our guts.

We have tens of trillions of bacteria and other microbes in our guts—at least one for each of our own human cells. Some species within this microbiome are passers-by, which we pick up from our food and our environments. But others are much older companions.

Andrew Moeller from the University of California, Berkeley, has found that there are a few groups of human gut bacteria whose history pre-dates humanity. Their ancestors lived in the guts of ancestral apes, and as those ancient animals diverged into modern species, the microbes did, too. In technical terms, they co-speciated. In simpler ones, if you drew out their family tree, you’d get ours for free; you could reconstruct the evolution of apes simply by comparing the right bacteria in their bowels.

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