10% HUMAN

This state-of-the-science survey explores and explains what is known about the microbial community that lives within us and what we have yet to learn.

In a welcome antidote to the simplistic “boost your health with probiotics” books and articles posing as science (but serving mostly commerce), Collen dares to tell the messy truth about what science knows—and doesn’t know—about the microbes that live in us, live with us, and in some ways even become us. An evolutionary biologist with several degrees, the author is clearly an expert in the field. Happily for readers, she’s also an experienced science writer who is equally at ease offering firsthand tales from her rain-forest expeditions and parsing complex laboratory experiments. She balances these nicely, though her overall emphasis is on the science. What makes even a step-by-step explanation of experimental protocol fascinating here, though, is twofold. First, Collen always brings the story back to the human level, telling, for instance, the tale of a courageous mother who tracked down a possible bacterial precursor to autism. Second, she never stops at simply reporting the outcome of a given experiment or data set. For example, instead of jumping to the logical conclusion that higher worldwide fat and sugar consumption have led directly to the obesity crisis, she steps outside the box and asks whether the trouble is what we’re eating or what we’re not eating. If fat and sugar calories have displaced microbe-friendly foods like high-fiber vegetables, she notes, the body’s biome has likely also changed. What impact would that have on our collective weight? Collen never claims that she has uncovered the answers to modern health woes, but she points out the markers that may one day lead to such answers.

Everything you wanted to know about microbes but were afraid to ask.