There are many ethnicities of man, but according to microbes, there are only three kinds of people:
Our gut contains trillions of bacteria, known collectively as the microbiome. Their cells outnumber our own by ten to one. We are, to the closest approximation, thriving communities of bacteria encased in a human shell. No two people have quite the same collection – we differ slightly in the species we contain, and there can be hundreds jostling for space.
But this variation isn’t infinite. Previous studies have shown that once people reach adulthood, their microbiomes become remarkably stable. Even after the communities are rocked by antibiotic assaults, they rebound to their old selves, recruiting members in the same proportions as before. Now, Manimozhiyan Arumugam and Jeroen Raes from the European Molecular Biology Laboratory (EMBL) have found that these constraints go even further. There seem to be just three preferred ways of building a community of gut bacteria.
Why is this useful? Because it can help doctors:
Enterotypes aren’t quite as well-defined as, say, blood groups, but they could have similar uses as medical markers. The microbiome helps us to digest our food and it affects our susceptibility to diseases; the enterotypes could reflect these roles. Each enterotype was dominated by a specific genus of bacteria, and varied in the proportions of the other members. They produce energy in subtly different ways, they’re particularly efficient at breaking down different nutrients, and they specialise at creating different vitamins.
Ed Yong of Not Exactly Rocket Science blog has the details: Link