Freethought & Rationalism Archive

beausoleil · 06-04-2002, 05:32 PM

Quote:

Originally posted by joshack:
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Looks to me like you all are arguing functionalism vs. historicism (or Gould-ism if you will). The effect of chance vs. the power of selection. In a sense you are both right - genetic drift is basically the random flow of traits through a population. It is probably less unusal than many think, but natural selection MUST be a more powerful force (assuming environmental differences). Any trait that arises "randomly" that is beneficial or deleterious for an organism will cause natural selection to kick in. Most mutations are neutral it is true. But given a non-stationary environment, it is inevitable that mutations will eventually bring either advantages or disadvantages. This does not mean that ALL traits exist because they are adaptive, but it makes it likely that that is why they originally arose.

The only possibility of having drift outweight natural selection is if the environment is absolutely constant and mutations function in an entirely neutral manner.
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Not really what I'm arguing. Suppose a mutation occurs that, combined with a change in environment, gives the creatures that carry it a 99.9% chance of prevailing against the opposition and filling a niche. If the 0.1% route is the one that leads to intelligence, then the 0.1%, less competitive, route is what is preserved in our fossil record. That would be the weak formulation of 'anthropic evolution', albeit expressed very simple mindedly.
The corollary is that, if we look at steps in our planet's history that 'led' to our evolving, we can't assume they represent the prevailing of a mutation that conveyed an advantage.

A mischievously strong formulation would be that virtually every adaptation on our planet is necessary if we are to be having this discussion, and that the appearance of natural selection as the dominant force in our planet's past is an illusion. Would an advanced civilisation be possible on a planet where species weren't well adapted to a large variety of ecological niches? I mostly jest.

I'm not arguing the relative effects of chance and selection in the general case. I'm pointing out that the general case is not necessarily relevant to the particular case of a planet with intelligence since that is clearly a self-selecting special case. However, insofar as ideas about the relative strengths of chance and natural selection rest on observation of the Earth's history their extension to the general case would be questionable.

Gar · 06-06-2002, 05:17 PM

Hmmm, ever think of proving you own argument, rather than attacking someone else's that you don't understand?

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06-06-2002, 05:17 PM	#42
Gar Regular Member Join Date: Apr 2002 Location: Boston, Mass Posts: 347	Hmmm, ever think of proving you own argument, rather than attacking someone else's that you don't understand?

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