Dolly was history's first cloned mammal. In February of 1997 it was announced that the biotechnology firm PPL Therapeutics and the Roslin Institute of Edinburgh, Scotland had successfully cloned a sheep, under the direction of Dr. Ian Wilmut. Cells from the udder of a pregnant six year-old sheep were inserted into the uterus of another sheep to develop, and Dolly was born in July of 1996. (Her name was a sly nod to singer Dolly Parton.) Dolly had the DNA of her source, making her the first mammal successfully cloned using adult cells. Dolly was put to sleep in 2003 after doctors detected progressive lung disease, though she had only reached half the lifespan of a typical sheep.