Scientists have demonstrated that organisms with greater complexity are more likely to evolve in complex environments, according to research published this week in PLOS Computational Biology. The researchers, based at École Polytechnique Fédérale de Lausanne and University of Vermont, created a programme that simulated the evolution of virtual creatures in a variety of landscapes.

Each virtual organism was made using a particular form of genetic encoding to create three-dimensional models and then simulated in a physically-realistic virtual world. Creatures that evolved in flat landscapes had a simple shape, but could not adequately navigate more complex environments. Later environments were designed with elevated "ice blocks". These obstacles were constructed so that each organism had to reach inside the gaps between the blocks to move forwards.

Overall, the researchers found that the investigated environments actively induced selection on the body plans and nervous systems of the simulated creatures. More complex landscapes led to more complex organisms than simpler environments due to the cost inherent in morphological complexity: evolution only produces complex body shapes in environments that demand them.

Study author Joshua Auerbach comments:

"Our work supports the idea that the morphological complexity of organisms is influenced by the complexity of the environments in which they evolve. While our work does not prove anything about biological complexity, it does provide a new methodology for investigating questions about the evolution of complexity in silico."

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Financial disclosure: This work was supported by National Science Foundation Grant PECASE-0953837 and DARPA M3 grant W911NF-1-11-0076. The authors also acknowledge the Vermont Advanced Computing Core which is supported by NASA (NNX 06AC88G) at the University of Vermont for providing High Performance Computing resources that have contributed to the research results reported within this paper. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Citation: Auerbach JE, Bongard JC (2014) Environmental Influence on the Evolution of Morphological Complexity in Machines. PLoS Comput Biol 10(1): e1003399. doi:10.1371/journal.pcbi.1003399

Please add this link to the freely available article in online versions of your report (the link will go live when the embargo ends): http://www. ploscompbiol. org/ article/ info:doi/ pcbi. 1003399

Contact:

Dr. Joshua Auerbach

École Polytechnique Fédérale de Lausanne

Laboratory of Intelligent Systems

Lausanne, Switzerland

+1 (802) 239-4955

joshua.auerbach@epfl.ch

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