Joshua Lederberg (lā´dərbûrg´), 1925–2008, American geneticist, b. Montclair, N.J., grad. Columbia, 1944, Ph.D. Yale, 1948. He is known for his studies of the genetic mechanisms of bacteria. He shared with G. W. Beadle and E. L. Tatum the 1958 Nobel Prize in Physiology or Medicine for establishing that sexual recombination occurs in bacteria. Lederberg showed that although bacteria reproduce only by dividing, they are able to effect sexual recombination by processes that result in exchange of genetic material between different bacteria. A pioneer in the fields of bacterial genetics, microbiology, and molecular biology, he taught at the Univ. of Wisconsin (1947–59) and Stanford Univ. (1959–78) and joined Rockefeller Univ. in 1978 as its president, serving until 1990.