Early work on evolution focused on natural selection’s key role in shaping the tree of life. In the 1960s, however, biologists started to appreciate the intricate patterns of genetic and ecological diversity that could emerge even without selective pressure. This “neutral theory” perspective has changed the way we see evolution, both figuratively and literally. I’ll illustrate some basic features of neutral theory using 1d voter models, which provide an evocative cartoon picture of genetic and ecological drift. We’ll see how questions about the persistence and spatial organization of lineages can be rephrased, in these models, as questions about random walks. By reducing geography to a neat grid, and letting color space stand in for the vast space of genetic variation, we’ll put the tree of life on a scale that our eyes and minds can grasp.

Gerhard Richter (born 1932) is considered one of the most important figures in contemporary art, with a remarkable heterogeneity of work, from figurative to abstract painting. Richter worked on grid paintings in the 1960s and 1970s, when he reproduced industrial colour charts as used by paint manufacturers. One of these paintings is '1024 Farben' from 1973. Richter developed a system for selecting 1024 different colour shades starting from the three primaries plus grey, and applying "subdivision through equal gradation”. The arrangement of the colours selected for the 32x32 element grid was done by a random process. In the text for an exhibition catalogue, Gerard Richter observes that "if I had painted all the possible permutation, light would have taken more than 400 billion years to travel from the first painting to the last". In fact, the time required would be much longer. In the extremely large population of alternative configurations to the original painting, there are certainly many interesting arrangements, which could have been generated by the random process. A system was developed to find the 1024-permutation that best matches any given base image, using optimisation techniques and colour distances as a measure of colour similarity. The results indicate that it is usually possible to recognise the base image content in the 1024-permutation, even for complex images.

Gerhard Richter (born 1932) is considered one of the most important figures in contemporary art. He worked on grid painting Colour Charts since the 1960s, initially attracted by the typical Pop Art aestheticism. The first colour charts were unsystematic, based directly on commercial colour samples. Later Richter became more interested in the neutral and systematic categorization of the colours chosen arbitrarily and drawn by chance. A colour distance provides a numeric representation of the similarity (or difference) between two colours. The representation of colour distances in a Cartesian coordinate system allows for an easy and direct connection of the perceived similarity / difference between colours and the corresponding numeric measurement. A set of 3 colours can be spatially represented in a 2D diagram as a triangle, and for 4 colours, as a pyramid in a 3D diagram. More than 4 colours can be represented in a higher dimensional space, or in a 2D diagram with some level of compromise (error). A method was developed to create 2D diagrams that present the perceived colour similarity / difference between adjacent elements in Colour Chart paintings. All relevant information (spatial structure and colours) is extracted automatically. The colour diagrams are created using an iterative process, which is optimized to minimize the representation (or diagram) error. The process proved effective for Colour Charts with a small and medium number of elements.