Hangman as analogy for Natural Selection

My concern is that this analogy makes it sound too much as though evolution has a preset goal that the traits are aiming at (which is an error that's already pretty pervasive).

So I would either explicitly address that problem when you're pulling out this analogy, or tweak it to make it sound less telos-y. (Maybe you're playing hangman in French, or some other language you're not fluent in and you're just trying to make any real word of that length? But the more letters you lock in, the fewer possible answers are available?)

I only have a layperson's knowledge of evolutionary biology, so my criticisms might miss some important subtlety, but it seems to that your analogy is significantly misleading in a couple of ways. It does convey the idea that random guesses with incremental feedback is a better search strategy than if the feedback were holistic (e.g. if you were guessing whole words and the only feedback were whether the guess is correct or not). In so far as someone's worry about natural selection is that they're mistaking it for the latter sort of search, the analogy may be helpful. But if you want to convey something more specific about how natural selection works, then I'm afraid the analogy isn't all that great.

One drawback of the analogy is in the nature of the environmental feedback. In Hangman, a letter gets fixed if (and only if) it is part of the correct answer. In genuine natural selection, though, a mutation doesn't get fixed because it is part of a complex set of mutations that collectively confer some phenotypic benefit. The environment isn't forward-looking like that; it doesn't say "This mutation is part of what is needed for optimality, so I'm going to hold onto it for that reason." Each individual mutation, in order to get fixed in the population, must confer some immediate reproductive benefit. Merely being one element of some complex group of mutations that is collectively beneficial is insufficient. The hangman analogy doesn't capture this aspect of natural selection.

This actually leads the analogy to kind of play into the hands of "irreducible complexity" critiques of natural selection. The proponents of such critiques presume that the individual parts of some complex adaptation only benefit the organism to the extent that they are part of that complex adaptation, and hence one cannot explain their selection without supposing that there is some forward-looking element to selection which holds onto those individual changes just because they will eventually contribute to a complex adaptation. This forward-looking aspect is then offered as evidence of intelligent design.

Another big drawback is that the analogy doesn't capture the competitive nature of natural selection. Natural selection occurs in populations, and requires both variation in traits among individuals in the population and competition for resources among those individuals. The Hangman analogy suggests that the environment already has a fixed template for the ideal phenotype and that it punishes organisms (or genes) individually for failing to approach this ideal and rewards them for getting closer to the ideal. If you have a population, and things worked in the Hangman way, there would be no correlation between rewards and punishments. But that's not how natural selection works. Genes are rewarded for contributing to their vehicles (organisms) being more reproductively successful than other organisms in the population. A reward just consists in reproducing more than your competitors, and a punishment just consists in reproducing less, so rewards and punishments are correlated. One allele can't get rewarded without another one getting punished.

On a similar subject, the boardgame Guess Who is a perfect illustration of the point in Burdensome Details. Each additional claim about Person X (do they wear glasses? are they blond?) leads you to knock down some possibilities.

I was also inspired by one of Dawkins' books suggesting something similar. It was some years ago but I believe Dawkins suggested writing a type of computer script which would mimic natural selection. I wrote a script and was quite surprised at the power it demonstrated.

As I remember the general idea is that you can type in any string of characters you like and then click the 'evolve' button. The computer program then:

1) generates and displays a string of random characters of the same length as the entered string.

2) compares the new string with the displayed string and retains all characters that are the same and in the same position.

3) generates random characters in the string where they did not match in 2 and displays the full string.

4) If the string in 3 matches the string entered by the computer the program stops otherwise it goes to step 2.

The rapidity with which this program converges on the one entered it quite surprising.

This simulation is somewhat different from natural selection especially in that the selection rules are hard coded but I think it does demonstrate the power of random changes to converge when there is strong selection pressure.

A fascinating aid in demonstrating natural selection was built by Darwin's cousin Francis Galton in 1877. A illustration and description can be found here. The amazing thing about this device is that, as described in the article, it has been re-discovered and re-purpose to illustrate the process of Bayesian inference.

I have come to consider this isomorphism between Bayesian inference and natural selection or Darwinian processes in general as a deep insight into the workings of nature. I view natural selection as a method of physically performing Bayesian inference, specifically as a method for inferring means for reproductive success. My paper on this subject may be found here

Related: rolling many dice and getting all sixes

http://www.creationtheory.org/Probability/Page03.xhtml