Trillions of bacteria living in and on the human body play a vital role in preserving health. But C-section births, antibiotics and excessive hygiene have been disturbing our microbial balance and possibly contributing to intestinal ailments, obesity, allergies and autism.

Deep in the Amazon basin, where traditional hunter-gatherers still live, researchers gave the indigenous population a lesson in biology. They used posters to explain to the inhabitants of the rain forest that a human being is never alone. Invisible, tiny creatures known as bacteria live on and inside our bodies — and they can be quite useful.

The lesson was part of a project to research the bacteria of the local people. “When we asked them for samples of their feces, the people laughed,” said one of the participating biologists, Maria Gloria Dominguez-Bello, from the University of Puerto Rico. Researchers succeeded in winning their trust, and the inhabitants of 10 huts allowed them to take swab samples, not only from their stool, but also from their hands, feet, noses and mouths.

The search for microbes aims to shed light on the nature of mankind’s original bacterial flora. These indigenous test subjects have had almost no contact with outside civilization. Their bacteria are a virtually unadulterated product of evolution. Microorganisms help digest food, supply the body with vitamins, train the immune system and ward off harmful pathogens.

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