Humanity's Strange FaceStone Age skull stokes debate over what it takes to be human Bruce Bower In June 2003, three cave researchers prepared for what they hoped would be a return to the Stone Age. The explorers strapped on scuba gear and plunged into a lake in Romania's Carpathian Mountains. These intrepid souls, led by Stefan Milota of Pro Acva Grup in Timisoara, Romania, swam one at a time into a rocky passage that snakes up into an adjacent limestone hillside. At the top of the 80-foot-long channel, they emerged into the musky air of a pitch-dark cave that most...