“In the early 1900s, scientists discovered that each person belonged to one of four blood types. Now they have discovered a new way to classify humanity: by bacteria. Each human being is host to thousands of different species of microbes. Yet a group of scientists now report <a href=”http://www.nytimes.com/2011/04/21/science/21gut.html”>just three distinct ecosystems in the guts of people they have studied</a>.
“The researchers, led by Peer Bork of the European Molecular Biology Laboratory in Heidelberg, Germany, found no link between what they called enterotypes and the ethnic background of the European, American and Japanese subjects they studied.
“Nor could they find a connection to sex, weight, health or age. They are now exploring other explanations. One possibility is that the guts, or intestines, of infants are randomly colonized by different pioneering species of microbes.
“The microbes alter the gut so that only certain species can follow them.
“The discovery of the blood types A, B, AB and O had a major effect on how doctors practice medicine. They could limit the chances that a patient’s body would reject a blood transfusion by making sure the donated blood was of a matching type. The discovery of enterotypes could someday lead to medical applications of its own, but they would be far down the road.
“‘Some things are pretty obvious already,’ Dr. Bork said. Doctors might be able to tailor diets or drug prescriptions to suit people’s enterotypes, for example.
“Or, he speculated, doctors might be able to use enterotypes to find alternatives to antibiotics, which are becoming increasingly ineffective. Instead of trying to wipe out disease-causing bacteria that have disrupted the ecological balance of the gut, they could try to provide reinforcements for the good bacteria. ‘You’d try to restore the type you had before,’ he said.”