Happy birthday to you, Happy birthday to you, Happy birthday dear Dolly the Sheep, Happy birthday to you!
After 277 attempts, Dolly - the world's first cloned mammal, was born on the 5th July 1996 at the Roslin Institute in Edinburgh, thanks to the work of Ian Wilmut, Keith Campbell and their talented colleagues. However, her existence wasn't revealed to the world's media until several months later, in February 1997. Living until seven years of age before succumbing to lung disease and producing six normal lambs of her own in the usual biological way, Dolly was living proof of the power of reproductive cloning - taking the DNA of an adult cell, in this case from a mammary gland of an adult female sheep, and putting it into a sheep's egg cell from which the DNA had been removed.
Arguably the most famous sheep in the world, Dolly's creation sparked huge scientific and sociological discussions, with some people accusing scientists of 'playing God' and riding down a slippery slope to human cloning, while others saw potential advances for biomedical and agricultural research, as well as opening a door onto understanding how the unique environment of the egg can wind back the biological clock of an adult cell, and turn it back into an embryonic one. Since then, we've seen an entire menagerie of cloned animals appearing, from cloned cattle, camels and cats to dogs, mules and even monkeys. But - as yet - no cloned humans, due to an international moratorium on the practice.
We'll be bringing you a special edition of the Naked Genetics podcast from a symposium being held at the Roslin Institute in September, looking in detail at Dolly's scientific legacy, but for now - happy 20th birthday, Dolly.