The first time artificial embryo twinning was successfully used was in 1885, performed by Hans Adolf Edward Dreisch. He showed that by shaking a two celled sea urchin embryo, you could separate the cells, which then developed into two separate sea urchins. Then, in 1952, the first successful nuclear transfer was performed by Robert Briggs and Thomas King. They moved the nucleus from an early tadpole embryo into a frog egg which had had its nucleus removed. The cell then grew into a tadpole. In 1984, the first mammal was created using nuclear transfer, by Steen Willadsen. He separated one cell from an 8-cell lamb embryo, and then was able to use a small electric shock to fuse it into an egg cell with no nucleus. This turned into an embryo, and days later they placed the embryo into a surrogate mother sheep, who had three baby lambs. In 1996, Dolly, was the first mammal created by somatic cell nuclear transfer. Ian Wilmut and Keith Campbell transferred the nucleus from an adult sheep udder cell into an unucleated egg to try and make a lamb. There were 277 attempts, but only one created an embryo, which was then placed into a surrogate mother. The result was a lamb named Dolly. Since Dolly there have been many other important cloning breakthroughs, such as the 1997 nuclear transfer from genetically engineered laboratory cells, 2001 the first endangered animals cloned by somatic cell nuclear transfer, and in 2013 human embryonic stem cells were created by somatic cell nuclear transfer.