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Darwin’s Catch-22: Too much nothing or too much junk


Evolution News and Views

From Evolution News & Views:

#6 of Our Top Stories of 2015: Peer-Reviewed Paper Reveals Darwin’s Unavoidable Catch-22 Problem

A new peer-reviewed paper in the journal Complexity presents a computational model of evolution which shows that evolving new biological structures may be deterred by an unavoidable catch-22 problem.

The article by physicists David Snoke, Jeffery Cox, and Donald Petcher begins by observing that in order to produce a new system, evolution first needs to try lots of new things. It must generate many, many variations upon which natural selection can act in order to “find” something useful to retain. But that comes with a potentially fatal cost. In the scenario proposed by Darwinian theory, you’d end up with an organism full of suboptimal or useless parts. As the authors put it:

[T]here is an additional energy cost to increased complexity. … In real systems, building new systems is costly, and the cost of carrying along useless or redundant systems is one of the arguments for the efficiency of existing living systems, as excess baggage is dropped as too costly.

(David W. Snoke, Jeffrey Cox, and Donald Petcher, “Suboptimality and Complexity in Evolution,” Complexity, DOI: 10.1002/cplx.21566 (July 1, 2014).)

The problem can be circumvented but only by providing something like an incentive system, a reward for trying out new variations. But then the difficulty arises: If you don’t make the “reward” high enough, you never evolve anything new. On the other hand, if you set the reward too high, too many new things are tried, many of which don’t do anything useful, and the system tends to accumulate deleterious junk. They explain: … More.

Gotta be random. Right? Or else.


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