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microbiome, the greater the feeling of general well-being. Studies have shown that children who grow up on a farm and have a lot of contact with various animals and many kinds of food are less susceptible to disease and allergies. And researchers have found that a well-tuned intestinal biotope is populated by a large number of competing bacterial species and is important for our health. But that internal equilibrium is increasingly impaired by an unbalanced diet and the many antibiotics that are either prescribed for us or ingested with our food after being used to fatten up the animals we eat. Microbiologists warn of dire consequences for the human gut—the situation is comparable to the destruction of species happening in the Amazon rain forest, where many species are becoming extinct before they can even be discovered and identified. The human intestinal tract is home to fewer and fewer organisms all the time, and some of the ones that remain are dangerous.

WHAT DOES MY GUT KNOW ABOUT ME?

Our intestinal microbiome reveals our lifestyle. Bioinformatician Peer Bork says: “Give me a stool sample, and I’ll tell you who you are.” This is true even in infants, whose stool indicates the state of their mother’s gut health, particularly if the baby is breast-fed. That is one of the findings to come out of a Canadian cohort study of 1,249 mother-baby pairs. “The results suggest breast milk may serve as an incubator that enriches, protects, and transports certain bacteria to a baby’s intestinal tract,” says microbiologist B. Brett Finlay, who co-authored the study. “This may give us clues about which bacteria are good probiotics.” Meanwhile, a number of American researchers have found evidence that the bacteria in our food can greatly influence our actions and feelings. Intrigued by the prospect, researchers at Weill Cornell Medicine