It’s often said that the bacteria in our bodies outnumber us 10 to one. Better calculations in recent years have reined in that conclusion, but today’s estimates are hardly less astounding: the real ratio seems to be about one to one. Fifty percent of the cells that make up the entity you call “you” are, in fact, microbial.
Granted, they are minuscule compared with human eukaryotic cells. They total perhaps a pound, meaning we can still claim the bulk of our weight. And these shifting guesses don’t really have implications for our wellbeing or, well, anything at all. “It’s more a catchy thing,” says Ruth Ley, director of microbiome science at the Max Planck Institute for Developmental Biology.
But they do highlight the remarkable fact that, in one sense, fully half of what we believe to be “ourselves” does not take the form we typically imagine. It’s a collection of ...
