Scientists confirm Alan Turing's 60-year-old theory for why tigers have stripes

Alan Turing was a brilliant mathematician, cryptographer, and logician, plus the father of computer science and artificial intelligence. He also worked in biology, and now, 58 years after his tragic death, science has confirmed one of his old biological hypotheses.

Turing's idea was that biological patterns - such as a tiger's stripes or a leopard's spots - are formed by the interactions of a pair of morphogens, which are the signaling molecules that govern tissue development. The particular pair that Turing proposed was an activator and an inhibitor. Turing proposed that the activator would form something like a tiger's stripe, but then interaction with the inhibitor would shut down its expression, creating a blank space. Then the process would reverse, and the next stripe would form. The interaction of these two morphogens would combine to create the full stripe pattern.

This hypothesis has remained mostly just speculation until now, as researchers at King's College London have now tested the idea in the mouths of mice. The roofs of mice's mouths contain regularly spaced ridges, and the researchers discovered the precise two morphogens that were working as activator and inhibitor to create the pattern, just as Turing suggested. What's more, when the researchers tampered with one morphogen or the other to increase or decrease their activity, the pattern of the ridges changed just as Turing's initial equations predicted they would. Researcher Dr. Jeremy Green adds:

"Regularly spaced structures, from vertebrae and hair follicles to the stripes on a tiger or zebrafish, are a fundamental motif in biology. There are several theories about how patterns in nature are formed, but until now there was only circumstantial evidence for Turing's mechanism. 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. Although important in feeling and tasting food, ridges in the mouth are not of great medical significance. However, they have proven extremely valuable here in validating an old theory of the activator-inhibitor model first put forward by Alan Turing in the 50s."

Green also suggested that this first experimental confirmation of Turing's activator and inhibitor model could prove useful in regenerative medicine, where this knowledge could allow us to rebuild structure and patterns when using stem cells to replace damaged tissues. And, as Green pointed out, it's a nice way to ring in the 100th anniversary of Turing's birth by proving that his biological theory was, indeed, right all along.

Via Nature Genetics. Image by Dave Stokes on Flickr.