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PLoS Comput Biol. 2014 Dec 18;10(12):e1003966. doi: 10.1371/journal.pcbi.1003966. eCollection 2014 Dec.

Evolution of integrated causal structures in animats exposed to environments of increasing complexity.

Author information

1
Department of Psychiatry, University of Wisconsin, Madison, Wisconsin, United States of America.
2
Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan, United States of America.
3
Allen Institute for Brain Science, Seattle, Washington, United States of America.
4
Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan, United States of America; Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan, United States of America.

Abstract

Natural selection favors the evolution of brains that can capture fitness-relevant features of the environment's causal structure. We investigated the evolution of small, adaptive logic-gate networks ("animats") in task environments where falling blocks of different sizes have to be caught or avoided in a 'Tetris-like' game. Solving these tasks requires the integration of sensor inputs and memory. Evolved networks were evaluated using measures of information integration, including the number of evolved concepts and the total amount of integrated conceptual information. The results show that, over the course of the animats' adaptation, i) the number of concepts grows; ii) integrated conceptual information increases; iii) this increase depends on the complexity of the environment, especially on the requirement for sequential memory. These results suggest that the need to capture the causal structure of a rich environment, given limited sensors and internal mechanisms, is an important driving force for organisms to develop highly integrated networks ("brains") with many concepts, leading to an increase in their internal complexity.

PMID:
25521484
PMCID:
PMC4270440
DOI:
10.1371/journal.pcbi.1003966
[Indexed for MEDLINE]
Free PMC Article

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