February 22, 1997:
In Roslin, Scotland, scientists announce that they have successfully cloned an adult sheep they named Dolly. The cell used in the cloning came from an adult sheep’s mammary gland, hence the name Dolly. As in Parton. No joke. Or maybe it was.
After cloning was successfully demonstrated through the production of Dolly, many other large mammals have been cloned, including horses and bulls. The reprogramming process cells need to go through during cloning is not perfect and embryos produced by nuclear transfer often show abnormal development. Making cloned mammals is highly inefficient (Dolly was the only lamb that survived to adulthood from 277 attempts). Wilmut, who led the team that created Dolly, announced in 2007 that the nuclear transfer technique may never be sufficiently efficient for use in humans.
Cloning may have uses in preserving endangered species and may become a viable tool for reviving extinct species. In January 2009, scientists from the Centre of Food Technology and Research of Aragon, in Zaragoza, northern Spain announced the cloning of the Pyrenean ibex, a form of wild mountain goat, which was officially declared extinct in 2000.
Although the newborn ibex died shortly after birth due to physical defects in its lungs it is the first time an extinct animal has been cloned, and may open doors for saving endangered and newly extinct species by resurrecting them from frozen tissue. Cloning of domesticated animals could be important in the future production of transgenic livestock.