In recent years, research has shown that what people commonly think of as “their” bodies contain roughly 10 microbial cells for each genetically human one. The microbial mass in and on a person may amount to just a few pounds, but in terms of genetic diversity these fellow travelers overwhelm their hosts, with 400 genes for every human one. And a decent share of the metabolites sluicing through human veins originates from some microbe. By these measures, humanity is microbial.
In Science News, Susan Milius examines the world of microbes and looks at how animals are really “composite beings.” Read more science stories on Longreads.
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