How did the leopard get its spots? Codebreaker Alan Turing was right all along
He cracked the Nazi Enigma code, helped end the Second World War and is recognised as the father of computer science.
3:56PM GMT 20 Feb 2012
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But for his final challenge, Alan Turing turned his mathematical mind to one of the natural world’s most enduring riddles: how the leopard got its spots.
Now, 60 years on, scientists have discovered that Turing's theory for why repeated patterns occur in nature was absolutely correct.
In his 1952 paper The Chemical Basis of Morphogenesis, the code breaker proposed that animals’ stripes and spots are caused by the interaction of a pair of chemicals, dubbed ‘morphogens’.
One of the chemicals, he suggested, triggered cell activity, while the other hindered it. The way in which they interact would dictate where cells grow, creating familiar patterns on the fur of animals.
While scientists have been able to simulate Turing’s theory using computer models, for the first time scientists have identified the exact chemicals in action.
Researchers at King’s College London found the interaction between two morphogens named Fibroblast Growth Factor and Sonic Hedgehog dictated the ridge patterns in the mouths of mice, as predicted by Turing’s models.
The same theory applies to the stripes and spots of big cats, the number of bristles on a fruit fly, or the whorls on a leaf.
Dr Jeremy Green, a reader in Developmental Cell Biology, said the discovery could help progress the next generation of stem cell therapy by indicating how to build complex structures such as organs in a laboratory.
“There are several theories about how patterns in nature are formed, but until now there was only circumstantial evidence for Turing’s mechanism,” said Dr Green.
“Our study provides the first experimental identification of an activator-inhibitor system at work in the generation of stripes – in this case in the ridges of the mouth palate.”
While biological processes at work are highly complicated, the mathematics behind Turing’s theory was “ingeniously simple”, he said.
“He was a great British genius. He had the confidence to take a completely new field, biology, and ask, ‘What can I add to it?’”
The mathematician, who would have been 100 years old this June, was convicted of being a homosexual the month the paper was completed. He committed suicide two years later by eating an apple dipped in cyanide.
Dr Green is now studying precisely how the two chemicals react. “We know how the car performs. We now have to look underneath the bonnet,” he said.
The new study is published in the journal Nature Genetics.
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