Lessons from Daisyworld

Bardeen, Matthew D. “Lessons from Daisyworld.” (2009).


This thesis presents findings that suggest that the survival of the fittest is synonymous with the survival of the stable. Richard Dawkins laid out a compelling framework for looking evolution from the perspective of the gene. The Gaia hypothesis and niche construction point to the coevolution of gene and environment. Under the assumption that gene and environment co-evolve it is found that there is strong tendency for a system to seek stable solutions which may or may not optimise the organisms to the environment. It is argued that this thought should be the guiding principle when looking at the evolution of natural and man made systems. The thesis uses the framework of the Daisyworld model developed by Watson and Lovelock to demonstrate these ideas. To this end the original Daisyworld model is analysed and an analytical solution for the equations is provided. The analyses suggest a maximisation of growth rates in an system with evolving albedos. This behaviour is then compared to an two dimensional model of the Daisyworld and the differences are clearly enumerated. Following this an extension is made to the two dimensional model to allow the evolution of mutation rate. The model is then shown not to maximise growth rate, but instead stability. It also shows the evolution of levels of selection higher than the individual or gene and suggests that this is completely compatible with a gene level perspective. It is thus argued that the focus of evolution is not individuals or genes, but rather the systems of which they are a part.

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