Genetic tests track origins of 'first Asians'
NEW YORK Century-old hair samples and new gene tests are finally resolving the riddle of the Andaman Islanders, "the most enigmatic people on our planet," scientists report.
The few remaining Andamanese 400 or 500 people in four tribes occupy a cluster of remote islands in the Bay of Bengal in the Indian Ocean, a spot rarely visited by outsiders. The Andamanese have been called Negritos, often likened to African Pygmies.
The surprise is that the Andamanese may actually represent the first Asians, an early wave of migrants from Africa who reached the area more than 40,000 years ago and have remained different from most of the other native peoples of Asia, the South Seas and Australia.
The new findings fit into a debate about how and when the hominids who evolved in Africa to become Homo Sapiens moved out into the Middle East, Asia and the rest of the world. One relatively new idea is that beaches exposed by low sea levels provided a useful pathway, and the oceans supplied reliable food, allowing these humans to migrate easily. As their population expanded, they spread from Africa to Asia and beyond.
"Our data indicate that the Andamanese have closer affinities to Asian than to African populations, and suggest that they are descendants of the early Paleolithic (Stone Age) colonizers of Southeast Asia," the researchers concluded in a study published in November in the journal Current Biology.
This work on genetics and ancestry "is the first molecular genetic evidence on the affinities of the Andaman Islanders, arguably the most enigmatic people on our planet," the researchers said.
The new results come from genetic studies of the people and old hair samples stored in a museum, as part of a project run by Erika Hagelberg at the University of Oslo and eight members of her international team.
The debate continues about how many migrations there might have been, which routes were followed, how fast people traveled and exactly when the art of boat-building began.
According to one team member, molecular geneticist Peter Underhill at Stanford University, "Humans left Africa 44,000 or 50,000 years ago, or even earlier." The new evidence suggests that small native populations such as the Andamanese "are living, breathing evidence" for one of the first migrations, he said.
Some genetically similar descendants of those first migrants are still found in small, isolated minority groups in Laos, Tibet and Japan, Underhill said. The genes carried on men's Y chromosomes tell part of that story.
Similar studies of Y chromosome evidence, Underhill said, suggest that the Aborigines of Australia, the tribes of New Guinea and the South Sea islanders represent a separate wave of migrants who originated in Africa. But, unlike the ancestors of the Andamanese, they expanded south to inhabit what is now Indonesia, other islands and Australia.
Today, the Andamanese "exhibit low genetic variability," a phenomenon that fits their small numbers and their isolation, the researchers said.
The Andamanese are in danger of disappearing, the scientists added. Historically, "the Andamanese earned a reputation for ferocity due to their violent resistance to foreign intrusions," the team said. "They remained fairly isolated from the outside world until establishment of a British penal settlement after the Indian mutiny of 1857." Now, the few hundred remaining are ruled by India.