Our most powerful 21st-century technologies—robotics, genetic engineering, and nanotech—are threatening to make humans an endangered species. PHOTOGRAPHS: LEFT: PETER MENZEL; CENTER, TOP TO BOTTOM: GALLERIA DELLʼACADEMIA, FLORENCE/CANALI PHOTOBANK , MILAN/SUPERSTOCK ; TED SPIEGEL/CORBIS; ROGER RESSMEYER/CORBIS; ROGER RESSMEYER/CORBIS; S. MILLER/CUSTOM MEDICAL STOCK ; RIGHT: EVERETT COLLECTION From