Description:

Speaker:

Michel Milinkovitch, Department of Genetics and Evolution, University of Geneva

Title:

A Living Cellular Automaton: when Charles Darwin meets John von Neumann & Alan Turing

Abstract:

In vertebrates, skin colour patterns emerge from non-linear dynamical microscopic systems of cell interactions. We have recently shown that skin colour in ocellated lizards contrasts with this framework as a quasi-hexagonal lattice of skin scales establishes a green and black labyrinthine pattern. We analysed lizard colour dynamics over four years of their development and demonstrated that the pattern is produced by a cellular automaton (CA) that dynamically computes the colour states of individual mesoscopic skin scales, hence the corresponding macroscopic colour pattern. Using numerical simulations and mathematical derivation, we identified how a discrete von Neumann CA emerges from a Turing continuous reaction-diffusion (RD) system: skin thickness variation generated by skin scale 3D morphogenesis causes the underlying RD dynamics to separate into microscopic and mesoscopic spatial scales, the latter generating a CA. Our study indicates that the fundamental concept of CAs, as abstract computational systems, is an actual process generated by biological evolution.

Speaker Bio:

Michel Milinkovitch (PhD Yale University - USA / Brussels University - Belgium) is Full Professor in the Department of Genetics & Evolution at the University of Geneva (Switzerland). He is also a Group leader of the Swiss Institute of Bioinformatics (SIB) since 2014. As an evolutionary geneticist, he contributed to quantitative analysis and modelling in Molecular Phylogenomics and Applied Evolutionary Genetics. He has developed concepts, analytical tools, and algorithms/models for multiple sequence alignments, phylogeny inference and haplotypic network building. However, his recent focus (since 2008) is on Evolutionary Developmental Genetics (Evo-Devo), especially its Physics of Biology aspects. He specialises on non-classical model species in reptiles and mammals and integrates data and analyses from comparative genomics, molecular developmental genetics, physics experiments, as well as computer modelling and numerical simulations. Professor Milinkovitch has published over 100 papers in international peer-reviewed journals (including Nature, Nature Communications, Science, Science Advances, and PNAS) and has given over 100 invited talks and over 60 contributed talks/posters all around the world.

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