The maths of life
FOR me, there is one scientist who stands out above all the rest. Forget Hawking or Sanger, Lovelace or Hodgkin. I give you a war hero, a pioneer of the computer age, a martyr of the LGBT community and the forerunner of a whole field of science: I give you Alan Turing.
Turing is probably bestknown for his pioneering codebreaking work during World War 2, featured in Hollywood blockbuster The Imitation Game. He made the first breakthroughs into the German naval Enigma code, which eased the passage of allied ships across the Atlantic. He was also instrumental in creating a machine called the Bombe, an early forerunner of modernday computers that could routinely crack Enigma. Turing’s war work, for which he was awarded the OBE, saved countless lives and is conjectured to have significantly shortened the war.
Astonishingly, this was perhaps not even Turing’s most influential contribution to modern civilisation, and was certainly not his first. When he was at Cambridge, in 1936, Turing tackled a famous, and unresolved, mathematics challenge known as the ‘‘decision problem’’. In resolving it, Turing proposed a universal machine that could decide whether any given mathematical problem was provable or not.
In the universal machine, Turing introduced the idea of the stored programme computer years before such machines existed. More than a decade later, electronic technology had become sufficiently advanced to allow Turing’s ideas to make the leap from his brilliant mind into the real world. Although no one person can claim to have invented the computer, the descendants of Turing’s theoretical machine sit in billions of offices, homes and pockets around the world.
During his short academic career, Turing made towering contributions to a diverse range of areas, from pure mathematics to the theory of artificial intelligence. In 1952, aged 40, he wrote a lesserknown paper in a new area, which was no less brilliant than his preceding work. In ‘‘The Chemical Basis of Morphogenesis’’, Turing proposed a mechanism by which patterns might form in the early embryo known as ‘‘diffusiondriven instability’’.
The same mechanism, he realised, might account for a multitude of patterns in nature, including those seen on animal coats, suggesting a mechanism for how the leopard got its spots. In particular, Turing’s theory predicts that animals can have spotty bodies and stripy tails, but not the other way around, a prediction that is borne out in many species of animals.
His idea of using mathematics to untangle the secrets of life was highly influential in the development of the relatively new field of ‘‘mathematical biology’’. At the heart of this rapidly growing subject is the attempt to represent biological systems of interest mathematically or computationally, using models.
Today, Turing’s legacy — the idea of taking a quantitative approach to biology — is helping to unravel some of life’s most enigmatic mysteries. Mathematical biologists are attempting to understand how things can go wrong during the development of an embryo and to suggest the best way to tackle outbreaks of deadly diseases such as Ebola.