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Christopher Wills' Evolutionary Facilitation

Allen Smith allens at yang.earlham.edu
Fri Apr 24 17:17:02 EST 1992

In article <1992Apr18.055346.21073 at gn.ecn.purdue.edu>, prasanth at gn.ecn.purdue.ed
   u (Ravi K. Prasanth) writes:
> I recently read "The Wisdom Of The Genes" by Christopher
> Wills where he claims that evolution is getting easier with
> time. I am trying to understand that from a mathematical
> point of view and would greatly appreciate any help in
> answering the questions I have.
> Suppose that we have a random process and a bag of operators
> with which the process can be modified. For convenience, let
> us assume that time is discrete. Define a fitness function.
> Let f(n) be the fitness value of the state of the random
> process at time n. Does "evolutionary facilitation" described
> by Wills mean that the probability of f(n+1) being better
> (bigger or smaller) than f(n) is greater than 1/2 for any
> n ?
> In this mathematical model of evolution, at every time step
> we pick a subset of random operators from the bag and modify
> the process. Wills states that evolutionary facilitation is
> brought about by new kinds of mutation, gene level organization
> etc. Does this mean that to model evolutionary facilitation we
> must appropriately modify the operators in the bag ? Where does
> the information needed to modify the operators come from ?

        I haven't read the book, but I can see a problem in that what
determines evolutionary fitness will be entirely dependent upon the
external and internal (genetic, etc.) environment. Being a whitish-grey
moth works fine- until pollution blackens the trees.

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