South Korean researcher Woo Suk Hwang caused a scandal in 2005 by falsifying data about his attempts to make the first embryonic stem cells from cloned human embryos. However, new research shows that Hwang's team accidentally made stem cells by another method that some scientists believe could be as important as cloning.
The stem cells produced in Hwang's lab came from an embryo that grew from an unfertilized egg, not a clone, according to a new genetic analysis of the cells.
Some species can reproduce without fertilization by triggering an egg cell to develop into an embryo on its own, a process called parthenogenesis. A human embryo made this way can't develop into a fetus, so some scientists and bioethicists believe that parthenogenesis could sidestep the moral issues involved in harvesting stem cells from viable embryos.