Partial skeletons may represent new hominid

Finds claimed to illuminate evolutionary roots of Homo genus

Nearly 2 million years ago, an adult and a child walking through the South African landscape somehow fell through openings in a partly eroded, underground cave and died. Today, that fatal plunge has led to their identification as representatives of a new hominid species — and a contentious debate among paleoanthropologists over the pair’s evolutionary relationship to modern humans.