Susumu Tonegawa ( born 6 September 1939 ) is a Japanese scientist who won the Nobel Prize in Physiology or Medicine in 1987 . Susumu Tonegawa ( å æ å é Tonegawa Susumu , born September 6 , 1939 ) is a Japanese scientist who won the Nobel Prize for Physiology or Medicine in 1987 for his discovery of the genetic mechanism that produces antibody diversity .