Geographic variation of human gut microbes tied to obesity

Researchers know that obese people have a different balance of microbes in their guts: more Firmicutes, fewer Bacteroidetes. Now researchers have found that people living in northern latitudes have a greater proportion of the Firmicutes associated with obesity than do people living farther south, and a smaller proportion of Bacteroidetes. The implications are unclear, though microbes may evolve with people to better extract energy from food in colder climates.