The Nobel Prize in Physiology or MedicineAffiliations: John B. Gurdon, born in 1933, is at the Gurdon Institute, part of Cambridge University. Shinya Yamanaka, born in 1962, is a professor at Kyoto University and is affiliated with the Gladstone Institutes in San Francisco.

In Their Research: Mr. Gurdon discovered in 1962 that the specialization of cells is reversible. More than 40 years later, Mr. Yamanaka discovered how intactmature cells in mice could be reprogrammed to become immature stem cells.

In the Real World: Without this discovery, known as cellular reprogramming, Dolly the sheep and later cloning experiments would not have been possible. It also allows scientists to create human embryonic stem cells without destroying human embryos, sidestepping an approach long been fraught with ethical controversies.