04/13/2007 BY NOBUYUKI WATANABE, THE ASAHI SHIMBUN Humans may have trekked up a mountain 35,000 years ago in what is now Tochigi Prefecture to dig up raw obsidian ore to process into stone tools, archaeologists say. Trapezoid stone tools unearthed on Mount Takaharayama in the prefecture will shed light on early human history in Japan, they added. The tools indicate human beings at the start of the Upper Paleolithic Era (roughly 35,000 years ago) were already "mining" raw stones to produce tools, not just picking them up off the ground, the researchers said. Previous finds had led experts to believe...