Tracking Human Migration on a Micro Scale

A mummified iceman found thirty five years ago in the Italian Alps continues to talk to us from the dead. Dubbed 'Otzi' by scientists, the man lived five thousand years ago during the Copper Age and most likely died from an arrow wound.

Now scientists are examining the bacteria in his stomach to learn about the movement of ancient peoples. The bacterium is Heliobacter pylori, or H. pylori, and it's found in two-thirds of humans. By analyzing the genetic information of the bacteria, we gain insight into how people migrated and intermingled.

Scientists were able to isolate Otzi's H. Pylori DNA despite the challenge of separating it from all of his other DNA as well as the microbes that infiltrated as his body laid in the ice and dirt. Otzi's H. Pylori should have matched the strain found in today's Europeans, which is a combination of the African and Asian strains. But his was nearly purely Asian with just seven percent African. This suggests the two strains didn't come together in Europe until well after the Copper Age.

Though it's unclear who eventually carried the bacterium from Africa into Europe, it may have arrived through the Middle East with farmers who brought the agricultural revolution with them. That would be much later than the original estimate of nine thousand years ago.

Scientists will need to sequence many more ancient remains to confirm their hunches. We do know Otzi's H. pylori caused him an infection that can create stomach ulcers. Some of these ulcers can cause cancer and now we know this may have made ancient peoples sick.