Thursday, April 25, 2013
Who knew that Alan Turing was into biology.
Turing was of course the great computer theorist who helped crack the German Enigma code during the Second World War. In 1952, two years before his unfortunate and unnecessary death, he published a paper called "The Chemical Basis of Morphogenesis" that described how "two interacting chemicals diffusing through space could form interacting wave patterns that produce spots like a leopard's or stripes like a zebra's." (I quote from Science, 14 December.) After a long semi-eclipse, Turing's mathematical paper is now finding application in a number of areas of developmental biology, including the development of mouse paws.
I was struck by this illustration from Science of mouse paws formed by removing Hox genes from a developing mouse limb lacking the gene Gli3. The more Hox genes removed the more digits form, all apparently in conformity with Turing's equations. Paws to paddles.
When you come to think about it, cracking the German code may not be all that far removed from cracking the genetic code, which determines not only the number of mammalian digits but also (it seems) sexual orientation. I've told Turing's story here before, of how after the war he was found out to be a practicing homosexual and brought to trial. Convicted, he was offered the choice of imprisonment or chemical castration. He chose the latter, so that he might continue his theoretical work. He committed suicide at age 41.