Horvitz, H. Robert (1947-...), an American biologist, won the 2002 Nobel Prize in physiology or medicine for his research on how genes control the growth and development of organisms. The prize was also awarded to the South African-born British biologist Sydney Brenner and the British biologist John E. Sulston. The three scientists conducted research on the development, growth, and cell death of tiny roundworms called nematodes (see Nematode).