Alan Turing

A 1952 paper by Turing on self-organizing chemical patterns is cited throughout this literature as the starting point for reaction-diffusion models of embryonic pattern, in which periodic patterns arise from an unstable uniform state¹⁴. Turing also gave a device-independent definition of a computer⁵. Levin treats these two interests as one question⁶.

Born: 23 June 1912
Died: 7 June 1954
Country: United Kingdom
Field: computer scientist, mathematician, university teacher
In the library: 0 works, named in 12 passages elsewhere
Facts from: Wikidata · Wikipedia

Reaction-diffusion patterning

Funk reports that Adams and Levin traced spatially periodic, stable patterns arising from the instability of a homogeneous steady state to Turing's 1952 paper, and offered this as a mechanism for embryonic development¹. Durant and colleagues describe Meinhardt and Gierer as inspired by Turing when they proposed chemical systems with local self-activation and long-range inhibition³. Funk also compares metabolic patterns, which vanish when electron flow is blocked, to the Turing-Gierer-Meinhardt model².

Excitation and voltage patterns

Baluska and Levin note that Rosen showed in 1968 that Rashevsky's two-factor model of neuronal excitation is formally equivalent to Turing's scheme for morphogenesis. Pietak and Levin cite Turing for the point that pattern can arise by symmetry breaking in a homogeneous medium. They then ask whether voltage pre-patterns could emerge the same way in tissue, and test this in a simulation with positive feedback among cells⁴.

Computation and cognition

Bongard and Levin credit Turing with a formal definition of a computer that does not depend on the device. By it, any system with an internal state that reads and updates information counts, including organisms⁵. They add that the tape of such a machine can be hard to find in living systems. Levin argues that Turing's interest in unconventional intelligence and in embryonic self-organization were the same question, about matter that supports reprogrammable information processing⁶.

SourcesEach quotation was checked word for word against the passage it opens.

spatially periodic, temporally stable patterns arise from the instability of a homogenous steady state (first mentioned in a classic paper of Turing, 1952)Funk RH, 2015 · Endogenous electric fields as guiding cue for cell migration · open at passage 27
patterns arise by metabolic activators and inhibitors (similar to Turing-Gierer-Meinhardt model) which disappear when the flow of electrons is inhibitedFunk RH, 2015 · Endogenous electric fields as guiding cue for cell migration · open at passage 28
Inspired by Turing's reaction−diffusion mechanisms of biological pattern formation (Turing 1952), Meinhardt and Gierer proposed dynamical chemical systemsDurant F, Lobo D, Hammelman J, Levin M, 2016 · Physiological controls of large-scale patterning in planarian regeneration: a… · open at passage 40
Turing and others (Turing, 1952; Cross and Hohenberg, 1993) showed that pattern can spontaneously self-organize from symmetry breaking in initially homogeneous media.Pietak A, Levin M, 2016 · Exploring Instructive Physiological Signaling with the Bioelectric Tissue… · open at passage 125
Turing, however, provided a formal definition for computers that is device-independent: in summary, a system is a computer if it has an internal state, if it can read information from the environmentBongard J, Levin M, 2023 · There's Plenty of Room Right Here: Biological Systems as Evolved, Overloaded… · open at passage 57
It is no coincidence that Alan Turing was interested in both the question of intelligence in radically unconventional embodiments [254], and the question of self-organization of biological form during embryogenesis [255].Levin M, 2023 · Darwin's agential materials: evolutionary implications of multiscale competency… · open at passage 68