Bugs hold clues to human origins

An unlikely source has provided the answer to a long-standing question over how the geographically isolated Pacific Islands became populated: bacteria. By analyzing both genetic variations in human gut bacteria and linguistic evidence, scientists found that people migrated to the Pacific Islands approximately 5,000 years ago from Taiwan, two papers in this week's Science report. "This is the first paper where bacteria were specifically used for human migration patterns," says Mark Achtman, a population geneticist at the University College Cork, in Ireland. Combined, the studies support the "pulse-pause" theory of Pacific migration, in which agricultural peoples from Taiwan rapidly spread southeast, settling at different locations and growing in size. With new technological and cultural innovations, some of these settlers pushed further, through modern-day Philippines, Borneo and New Guinea, and, the study shows, eventually reaching the farthest Polynesian islands. A competing theory proposed that people gradually spread to the distant...