Evolutionary Relationships Hold, Even in Our Guts - ScienceNOW
The human body is coated with bacterial cells. They live on our skin and between our teeth. They particularly like our warm, nutrient-filled gut, where they help digest food, make vitamins, and produce some seriously smelly gas. But when it comes to these gut bacteria, we are not what we eat. A new analysis of feces from humans and several other primates finds that evolutionary history, not diet, determines the makeup of our intestinal bugs.
Babies are born sterile, then they start picking up bacteria from their mothers. These microbes multiply and fill the intestines; one adult's gut can hold a thousand species. But it's not clear what exactly influences the makeup of that community—that is, what particular species of bacteria, in what quantities, hang out in our guts. It could depend mainly on what we get from our mothers, on what we eat, or on some other factor. Scientists have started using new genetic techniques to work out whether different species of animals have different communities; some studies in recent years have concluded that animals with similar diets have similar microbial communities.