AGE: 61
OCCUPATION: Professor at the Institute for Integrated Cell-Material Sciences at
Kyoto University
NUMBER OF TIME COVERS: 0
PREVIOUS APPEARANCES ON THE TIME 100: 0
PRO: First in mouse cells and then in human ones, Yamanaka (working with James Thomson of the University of Wisconsin) proved that stem cells needn't come from human embryos — adult skin cells can be reprogrammed to act like stem cells.
CON: These cells tend to turn cancerous, as cancer-causing retroviruses are used to insert the genes into the cell's chromosomes.