Human Gut Microbes Took Root Before We Were Human

The relationship between humans and the bacteria in our guts extends far back into the past — to the time before modern humans even existed, a new study finds. Microbes in two bacterial families — Bacteroidaceae and Bifidobacteriaceae, which are present in humans and African apes — likely colonized the guts of a shared ancestor of both groups around 15 million years ago, the researchers discovered. The researchers' genetic data also tell a story of parallel evolution — in