Co-migration of man and bacteria

By Ann Griswold • Published: May 2nd, 2007
Category: Health in a Heartbeat

Humans had a lot to worry about sixty-thousand years ago, between scavenging for food, shielding themselves from predators and gearing up for their migration out of Africa. While it might seem hard to relate to their trials and tribulations, scientists have discovered that we share at least one complaint with our early ancestors… we’re both infected with an ulcer-causing bacterium called Helicobacter pylori [HEEL-ih-coh-bak-ter pie-LOR-ee].

More than half of all modern-day humans harbor Helicobacter [HEEL-ih-coh-bak-ter in their stomachs. Most of us don’t realize we’re infected, since only seven percent of American adults develop ulcers. But the often-overlooked bacterium has recently entered the spotlight… scientists say Helicobacter is akin to microbial bread crumbs that have helped illuminate our original migration out of East Africa and around the globe.

A recent article in the journal Nature describes how scientists used bacterial samples from people around the world to track the route taken by Helicobacter out of Africa. Not surprisingly, the bacterium followed the same route known to have been followed by humans… through India and East Asia, before eventually arriving in Europe.

The scientists examined subtle genetic differences in Helicobacter samples taken from people in Europe, Asia, Africa, the Middle East and South America. All of the samples shared elements with the ancestral East African population. Fewer samples were similar to the East Asian population, the next stop on their route. Using similar reasoning, the scientists were able to track the synchronous journey of humans and bacteria across the globe.