A population of Amerindian hunter-gatherers, who until recently had lived in isolation in the remote Venezuelan Amazon, is yielding a trove of information for scientists at Mount Sinai who are studying their microbiome and finding the most diverse levels of bacteria and bacteria-encoded functions ever discovered in humans. The human microbiome—comprised of trillions of microorganisms that inhabit our bodies—is believed to play a critical role in the well-being of the host.
“This is like having a time machine and going back in time to explore what microbes we used to harbor,” before exposure to antibiotics or processed food, says Jose C. Clemente, PhD, Assistant Professor of Genetics and Genomics at Icahn School of Medicine at Mount Sinai. He is the first author of a collaborative study with researchers in Venezuela and at New York University School of Medicine, University of Colorado, and Washington University School of Medicine. Their paper, which appeared in the April 17, 2015, issue of Science Advances, is the first attempt to document the microbiome of people with no previous exposure to industrialization whose lifestyles are similar to those of our human ancestors.
The Yanomami Amerindians in the study are the seminomadic descendants of people who arrived in South America approximately 11,000 years ago. They live in a mountainous region that is a two-week walk through thick, uncharted jungle to the nearest outpost. Their diet consists of wild bananas, seasonal fruits, plantains, palm hearts, cassava, birds, small mammals, small fish, crabs, and frogs. Unlike Westerners, who eat three large meals daily, the Yanomami consume small amounts of food all day long.
At Mount Sinai, Dr. Clemente and his research team are examining and characterizing the tribe’s bacteria. They are also comparing them to that of westernized populations in the United States and to bacterial communities found among the Guahibo Amerindians in Venezuela and rural villagers in Malawi who maintain traditional lifestyles but have been exposed to antibiotics and processed foods. To date, the findings show that bacterial diversity gradually decreases with acculturation—with the Yanomami having the highest, followed by the semi-acculturated Guahibos and Malawians—and the most industrialized populations having the least diversity.
“Lack of exposure to a variety of microbes can result in the immune system not being properly trained and eventually lead to the triggering of several immune conditions,” says Dr. Clemente. “Our long-term goal is to understand which bacteria might have protective effects and how we can reintroduce them for therapeutic purposes.” Scientists believe that bacterial changes among industrialized populations may play a role in the increased incidence of diabetes, heart disease, and obesity around the world.
By working with the tribe’s bacteria—taken from the skin, mouth, and feces of up to 30 villagers between the ages of 4 and 50—the scientists have an unprecedented opportunity to learn about microorganisms that might have been already eradicated in other humans and determine whether they are advantageous or deleterious to human health. “We can view these bacteria as endangered species. There is an urgent need to understand what’s there before it disappears,” Dr. Clemente says.
The study expands upon previous results from the Human Microbiome Project, a five-year initiative established by the National Institutes of Health in 2008 to understand the role that microbes play in health and disease. Advances in DNA sequencing technologies and culture-independent methods have made it possible for scientists to examine microbial communities in a much more comprehensive manner than was possible in the past.