Sunday, May 08, 2005

Re: Language for Talking, and Thinking, About Evolution

A reply to a comment from Bevan on my last post:

>Some interesting thoughts here James, I've got some of my
>own opinions :-).
>In the first section (situation instead of environment) I
>would more carefully consider who is using the term
>environment when analysing the correctness of its usage. I
>certainly consider environment to be more than the physical
>landscape. My housemate for example is doing her PhD in
>ecological modeling. She (and people in similar fields) do
>use the term environment correctly. Factors such as
>biodiversity, population distribution and the presence of
>predators / prey are all important consideration for them
>when talking about environment. You are certainly not going
>to convince them to change their correct use of environment
>to situation because a portion of population use the term
>incorrectly. Isn't it a matter of educating / correcting
>people on the proper meaning the of term rather than consider
>it tainted and ditch it for a new one?

I don't want to imply that nobody uses it correctly, but I still think that in practice people -- even some experts -- think of the envrionment in a too narrow way (regarding my note of 'even some experts', I think, for example, that some such mistaken thinking by experts was cleared up by John Maynard-Smith's Evolutionarily Stable Strategies (except I don't think that article describes it very well, but it was the best link I could find) concept).

If this is the case then of course their notion of 'environment' needs correcting. But with respect to describing evolution, I think that even if with a proper understanding of 'environment', the notion of 'situation' is a more /appropriate/ (not more correct) term.

I should also make it clear that I'm not trying to change anyone else's vocabulary, I'm just trying to figure out what I think is the clearest way of thinking about these concepts.

>Regarding the use of increase and optimise - note the s not
>the z you seppo :-). I agree that changes due to natural
>selection is better expressed using "optimise" rather than
>increase. There are however cases where an organisms fitness
>does increase due to natural selection. If a change in the
>organism results in that organism being far more successful
>in its environment does this note denote a increase in the
>fitness with respect to that environment? Success can be

I don't have any problem with the concept of fitness as something that can be increased or decresed. I think that optimisation -- with an 's' just for you! :-) -- leads to increased fitness. I think that it can cause problems however, to characterise evolution as a process that "increases fitness".

I think that doing so paints a picture of fitness as something like a numerical quantity that can be increased or decreased, and where you can compare these numerical values across different environments and species. I think that talking of evolution optimising fitness helps avoid these problems. Any particular optimisation will lead to an increase of fitness. But there's no universal measure of fitness that is you are constantly bumping up.

I think it's easy to misunderstand this point, and think that it implies some sort of extreme "fitness relativism" where there's no means to make any comparison in terms of fitness or in terms of other concepts such as "sophistication" or "complexity" of design.

Fitness may be relative to situation, and no two situations may be /completely identical/, but situations can share a lot of similarities. After all, every situation in this universe is under the same laws of physics (or at least I don't think we have any reason to believe otherwise). And there are surely certain types of abstract problem solving abilities that have a very broad range of applicability, to give another example.

>measured in a number of ways of course: population density,
>height in the food chain, susceptibility to harsh
>environmental changes, etc. Take the example of a carnivore
>diversifying its diet to become an omnivore. This will likely
>come about due to changes in its environment, e.g. lack of
>prey. If by widening its diet it really begins to flourish
>could this not be called an increase in the fitness with
>respect to its environment?
>There is some really good reading about this: Carl Sagan's
>book Cosmos (first 50 pages for so I think) has a very good
>argument for natural selection and explanation of how it
>happens. Jared Diamond's books 'The Rise And Fall Of The
>Third Chimpanzee' and 'Guns, Germs And Steel : A Short
>History Of Everybody For The Last 13,000 Years'. For
>something easier and more entertaining I've got the David
>Attenborough's 'Life of Mammals' DVDs. They've got some
>interesting explanations about the evolution of mammals.

Ah, all books that I would like to read but haven't yet :-). "Guns, Germs and Steel" in particular.

>Good luck with the PhD...


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