Blame Your Gut Bacteria

More evidence that our lives are controlled by the bacteria in our intestinal tracts:

Researchers led by Jeffrey Gordon, a biologist at Washington University in St. Louis, Missouri, set out to find direct evidence that gut bacteria have a role in obesity. The team took gut bacteria from four sets of human twins in which one of each pair was lean and one was obese, and introduced the microbes into mice bred to be germ-free. Mice given bacteria from a lean twin stayed slim, whereas those given bacteria from an obese twin quickly gained weight, even though all the mice ate about the same amount of food.

They found, alas, that if they fed the lean mice a really lousy diet -- i.e., what Americans typically eat -- they gained weight anyway.