Communications of the ACM
Computer Scientists Reproduce the Evolution of Evolvability
Hod Lipson
Credit: Cornell University
Modular systems evolve more easily than non-modular systems, but the evolution of modularity is a key open question for biology. However, Cornell University researchers led by Hod Lipson think they have solved the problem.
"Modularity evolves not because it conveys evolvability, but as a byproduct from selection to reduce connection costs in a network," according to the researchers.
They say examples of connection costs include the cost of manufacturing connections and maintaining them, the energy required to transmit information along them, and the signal delays that occur, all of which increase with the number of connections and their length.
Lipson recently ran a simulation using two different criteria. The first was a measure of whether a network was better at recognizing the input pattern or not. The second took into account the cost of running the network, with more efficient networks being deemed more fit. Both fitness criteria produced networks capable of accurately identifying the input patterns after 25,000 generations, but the second criterion produced modular networks while the first did not. The researchers say that is evidence that modularity emerges when network costs are taken into account.
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