Sorry for the delayed reply! The paper mentions that Santiago Ramón y Cajal already pointed out that evolution has created mostly short connections in animalMessage 1 of 2 , Feb 21View SourceSorry for the delayed reply!The paper mentions that Santiago Ramón y Cajal already pointed out that evolution has created mostly short connections in animal brains.
Minimization of connection costs should also encourage modularization, e.g., http://arxiv.org/abs/1210.0118 (2012).
But who first had such a wire length term in an objective function to be minimized by evolutionary computation or other machine learning methods?
I am aware of pioneering work by Legenstein and Maass:
R. A. Legenstein and W. Maass. Neural circuits for pattern recognition with small total wire length. Theoretical Computer Science, 287:239-249, 2002.
R. A. Legenstein and W. Maass. Wire length as a circuit complexity measure. Journal of Computer and System Sciences, 70:53-72, 2005.
Is there any earlier relevant work? Pointers will be appreciated.
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On Feb 6, 2013, at 7:48 PM, Jeff wrote:
I'm extremely pleased to announce a new paper on a subject that many--including myself--think is critical to making significant progress in our field: the evolution of modularity.
Jean-Baptiste Mouret, Hod Lipson and I have a new paper that
1) sheds light on why modularity may evolve in biological networks (e.g. neural, genetic, metabolic, protein-protein, etc.)
2) provides a simple technique for evolving neural networks that are modular and have increased evolvability, in that they adapt faster to new environments. The modules that formed solved subproblems in the domain.
Abstract: A central biological question is how natural organisms are so evolvable (capable of quickly adapting to new environments). A key driver of evolvability is the widespread modularity of biological networks—their organization as functional, sparsely connected subunits—but there is no consensus regarding why modularity itself evolved. Although most hypotheses assume indirect selection for evolvability, here we demonstrate that the ubiquitous, direct selection pressure to reduce the cost of connections between network nodes causes the emergence of modular networks. Computational evolution experiments with selection pressures to maximize network performance and minimize connection costs yield networks that are significantly more modular and more evolvable than control experiments that only select for performance. These results will catalyse research in numerous disciplines, such as neuroscience and genetics, and enhance our ability to harness evolution for engineering purposes.
There has been some nice coverage of this work in the popular press, in case you are interested:
National Geographic: http://phenomena.nationalgeographic.com/2013/01/30/the-parts-of-life/
Cornell Chronicle: http://www.news.cornell.edu/stories/Jan13/modNetwork.html
Please let me know what you think and if you have any questions.
University of Wyoming