Experts estimate the Hadzabe people have lived in the same area of northern Tanzania for more than 40,000 years. They are one of the world's last hunter-gatherer tribes, and they are fighting for survival. Since the 1960s, they've lost 90 percent of their land. But now, the Hadzabe have turned to a decidedly modern invention, the global carbon trading market, to help them preserve the forests they call home. For VOA, Willy Lowry has the story from the Yaeda Valley.