Cloning has been one of the biggest biological stories of the last 100 years. There haven't been any human clones yet, although human embryos have been cloned. But cows, dogs, cats, pigs, sheep have all had clones created. The technology has a long history. These are some of the landmark moments.
World famous German scientist Hans Spemann publishes Embryonic Development and Induction. The book contains the results of experiments he conducted on salamanders where he transferred the genetic material of a sixteen cell embryo into a single salamander cell with no nucleus. He also theorized that the process of cloning would be possible with differentiated cells.
The world's first ever successful animal cloning experiment. Robert Briggs and Thomas J. King successfully cloned tadpoles by nuclear transfer. The technology of cloning was making progress, as they transferred nuclei from embryonic cells into oocytes with their nucleus removed.
Crick and Watson publish their now world famous paper on the structure of DNA.
British scientist Sir John Gurdon clones a frog by nuclear transfer using differentiated adult cells. The experiments showed, for the first time, that the developmental pathway of an adult cell was reversible.
Dolly and Beyond
The big one. Ian Wilmut and Keith Campbell at the Roslin Institute in Scotland create Dolly the sheep - the world's first ever cloned mammal. They announce the birth the following year and the world's press beat a path to their door. The technology of cloning comes of age.
During this period several institutes around the world announce the successful cloning of many different animal species such as Snuppy the first cloned dog, horses, and cows.
At several times during this period Dr Severino Antinori, an Italian fertility specialist and Dr Panas Zavos announce together and separately various plans to clone humans. They made headlines, but possibly not babies. To date there are no reports of the birth of human clones.
South Korean scientists create several cloned human embryos which they only allowed to develop for a short while - just long enough to extract embryonic stem cells which could be used in the treatment of disease.