Check out this rather nifty Java Applet:

The Weasel Applet

The program was never intended to model evolution accurately, but only to demonstrate the power of cumulative selection as compared to random selection.

Weasel's 81-character alphabet:
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ 0123456789,.?;:'@!£$&%+-*/><

1.) Type a Goal Phrase using any of the characters listed above. The default Goal Phrase is SETI@Home will find ET

2.) Choose a population size, minimum is 2 (Population Size refers to the number of guesses per generation)

3.) Choose how frequently to update the display, after every n generations

4.) Start by clicking on Evolve A Solution, let it run until it completes, otherwise click on Stop Breeding! to stop

A non-technical description of Weasel

This exhibit, which was inspired by a description of a program in Richard Dawkins's excellent book The Blind Watchmaker , demonstrates the ability of evolutionary techniques to solve enormous problems rapidly.

The applet works like this:

A) You provide a phrase to one part of the program, the Scorer, and another part of the program (the Breeder) tries to make the Scorer happy by breeding possible solutions until it matches the supplied phrase.

B) The Breeder starts by making lots of random guesses and presenting each to the Scorer. The highest-scoring guess is then bred with other guesses (by combining parts of each guess) and some of the guesses are randomly mutated. The Breeder continues to breed and mutate guesses until it finds your original phrase.

C) Along the way, the Scorer only tells the Breeder how close each guess is to the target phrase, not what the target phrase is. The Scorer doesn't even tell the Breeder which parts of its guess are right or wrong. This is vaguely like trying to find a random spot in the galaxy, being told only how "hot" or "cold" you are after each step.

There are many possible phrases of the same length as the phrase "Methinks it is like a weasel" (that's well over 2 million billion billion billion billion billion phrases). An exhaustive search -- systematically trying all possible guesses -- would virtually never complete; the universe would run down first. But even the simple-minded evolutionary programming techniques used in this applet typically find a solution after examining only about sixty thousand alternatives.

More info here: Weasel program

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Sometimes I think we are alone in the universe, and sometimes I think we are not. In either case the idea is quite staggering.

Attempting to match `SETI@Home will find ET'


Population Size = 1024

Generation 0
Tries <= 1024
Best Critter .Dt4hc2mXND!hH8f-id4Ei
Score (0 is best) 18
.
.
.
.
Generation 139
Tries <= 36608
Best Critter SETI@Home will find ET
Score (0 is best) 0

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Join TeamACC

Sometimes I think we are alone in the universe, and sometimes I think we are not. In either case the idea is quite staggering.