A blackened, broken leg bone from Earth’s prehistoric past may hold the answer to when early humans diverged from apes and started their own evolutionary path.The fossilized find, first uncovered two decades ago, suggests that early humans regularly walked on two feet some seven million years ago... Since many consider bipedalism the major milestone that put our own lineage on a different evolutionary path than the apes, Sahelanthropus could be the very oldest known hominin—the group consisting of modern humans, extinct human species and all of our immediate ancestors.The species could even be our oldest non-ape ancestor, if its lineage...