A nomadic tribe from the forests of Thailand and Laos is providing anthropologists with new evidence that hunter-gatherer communities are not merely relics of the Stone Age.
The Mlabri hunt and forage for wild foods. Based on the tribe's location, many scientists assumed that the Mlabri came from the ancient Southeast Asian Hoabinhian culture that predates agriculture. Traditionally, anthropologists thought that modern hunter-gatherer tribes like the Mlabri descended through the ages unchanged. But an analysis of the tribe led by Mark Stoneking of the Max Plank Institute for Evolutionary Anthropology in Leipzig, Germany, indicates that these communities are more complex than previously imagined.
Stoneking and his team compared Mlabri DNA with that from neighboring tribes. Astonishingly, all of the Mlabri mitochondrial DNA turned out to be identical--a total lack of variation that hasn't been found in any other human population. As hunter-gatherer societies are thought to have less genetic diversity, the lack of variation suggests that the Mlabri descended from a hunter-gatherer culture. However, unlike other hunter–gatherer groups, the Mlabri share genetic information with neighboring agricultural hill tribes as well as other agricultural groups in Southeast Asia.
Tribal myths also support an agricultural background for the Mlabri. According to the legends of the Tin Prai, the Mlabri's agricultural neighbors, ancient villagers banished two children by sending them down a river on a raft. The children were the first Mlabri. Based on population simulations, a scenario like the Tin Prai legend, and not hunter-gatherer roots, best accounts for the mysterious lack of genetic variation. Even if the mother culture was an agricultural society, say the authors, with too few hands to farm, the original group would have probably reverted to hunting and foraging.
The results, published this month in the journal Public Library of Science, Biology, demonstrate that "hunter-gatherers have changed and evolved, particularly in response to interactions with agricultural groups," says Stoneking.
The authors make a compelling case, says Diane Gifford-Gonzalez, an anthropologist at the University of California, Santa Cruz, and an expert on the origins of farming. "Such a transition from farming to foraging for wild foods may have been done or attempted many times since the origins of farming," she says.