A team of researchers at the University of Pittsburgh and Brandeis University have provided the first experimental evidence that validates Alan Turing’s theory of morphogenesis, more than 60 years after his death. Turing is well known for his contributions to computer science, he set in motion the computer age and his World War II codebreaking helped turn the tide of the Second World War. Turing also developed theories in biology and chemistry. In his only paper in biology, Turing proposed a theory of morphogenesis, or how identical copies of a single cell differentiate, for example, into an organism with arms and legs, a head and tail.
A press release from the University of Pittsburgh has further details:
Turing, in 1952, was the first to offer an explanation of morphogenesis through chemistry. He theorized that identical biological cells differentiate and change shape through a process called intercellular reaction-diffusion. In this model, chemicals react with each other and diffuse across space—say between cells in an embryo. These chemical reactions are managed by the interaction of inhibitory and excitatory agents. When this interaction plays out across an embryo, it creates patterns of chemically different cells. Turing predicted six different patterns could arise from this model.
At Brandeis, Seth Fraden, professor of physics, and Irv Epstein, professor of chemistry, created rings of synthetic, cell-like structures with activating and inhibiting chemical reactions to test Turing’s model. Pitt’s G. Bard Ermentrout, University Professor of Computational Biology and professor of mathematics in the Kenneth P. Dietrich School of Arts and Sciences, undertook mathematical analysis of the experiments.
The researchers observed all six patterns plus a seventh unpredicted by Turing.
In addition, they noticed that, as Turing theorized in the 1950s, the once identical cell-like structures—now chemically different—also began to change in size due to osmosis. This may explain how some cells, further down the development assembly line, become large egg cells or tiny sperm cells.
The research “tells you how a zebra gets its stripes,” says Ermentrout. Turing’s theory underlies pattern formation in every biological area from pigmentation of seashells to the shapes of flowers and leaves and to the geometric structures seen in drug-induced hallucinations, he adds. Thus, validating Turing’s theory could have an impact on future research in fields ranging from embryology to neurology to cardiology. This research could impact not only the study of biological development but the study of materials science as well. For example, Turing’s model could help grow soft robots with certain patterns and shapes.
