Have you seen this?

Bacterial Ecosystems Divide People Into 3 Groups, Scientists Say

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 just three distinct ecosystems in the guts of people they have studied.

That may change as they study more ethnic groups and people from non-industrialised nations. But it is intriguing. It's also fairly timely. I'm reading a book right now called Allies and Enemies: How the World Depends on Bacteria, by Anne Maczulak, which describes the importance of bacteria in our oecosystem. So often the pathogens are what people think of, and that germs are bad. But bacteria actually protect us from disease, break down our food, and even help bring rain. It's pretty interesting, and it's not some dry microbiology text. It's also free on the Kindle, as opposed to $25 in print. :O)