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PDF 2.86 MB
Pages 294–301
First published 20 July 2015

Environmental bias forces parasitism in Tierra

Simon Hickinbotham and Susan Stepney


Tierra is an iconic ALife system. It has three innovative features: self-optimisation, parasitism, and an uncrashable execution environment. We have identified four sources of bias in the evolutionary dynamics of Tierra. We have run two sets of simulations: one with the original configuration of Tierra 6.02, and one with three of the biases removed. We find that the innovations observed in the original Tierra are preserved, and the debiased configuration is more amenable for future experiments with open-ended evolution.