Evolution (Introduction)

by xeno6696 , Sonoran Desert, Monday, July 27, 2009, 23:25 (5596 days ago) @ David Turell

One further discussion point is whether evolution is or is not purposeful (teleology).
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> Evolution certainly looks purposeful in the sense that it continuously changes toward the more complex. Complexity does not guarantee survivability, the key to natural selection. Gould in 'Full House' defends this by first pointing out that the only direction for random mutations is away from bacteria (one-celled animals or plants) to something more complex. (My feeling is why should bacteria became more complex; they have been successful as they are for 3.6 billion years? That supports the idea there is a drive to complexity in the evolutionary process.) For randomness Gould points out the 'drunkard's walk' and 'random walk' math to match random mutation. This certainly supports all the various banches of evolution in plants and animals. But the drunk has a purpose. He is trying to get home, and the odds are with him to a degree that he will get to his front door.
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> But if one looks at a diagram of random walk, the path can circle around, back up on itself. To me evolution doesn't seem to do that. How often are branches found that circle back to become less complex? 
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> So I am not sure that Gould has really clearly removed teleology from evolution.
> I hope our resident math expert, Matt, would comment. - Not sure what I can really offer here... I'm not that familiar with Gould's argument, and the random walks I'm used to are for things like maze solutions. I certainly haven't taken a course that does more than a few basic algorithms... - Taking a peek at some theorems that might shed some light, it looks like the "random walk hypothesis" from economics might shed the most light. Economics are often used in biological studies and evolutionary simulations usually are mathematically based on economics. (Especially consumption and any game-theory type competition.) - http://en.wikipedia.org/wiki/Random_Walk_Hypothesis - Using this as a rough analogy, I would assume that Turell would view the "random graph" as what he's talking about here, if complexity is charted on the y-axis and time on the x-axis, you would theoretically have instances where an organism would "de-evolve" as it were. But what exactly would "de-evolution" be? As the oceans acidify, coral will start to lose its skeletons. If an agressive form of coral manages to find a way to beat that, is that evolution or de-evolution? Bacterial evolution has been observed by deleting a gene (such as lactose edibility) and watching as a new gene (crafted from an older one) was created to metabolize lactose. I know selection has been working on North Atlantic Cod to make them small. Could this be de-evolution? I think the random walk thing would be in the tracing of a specific trait... and holy crap would that be complex if the trait was primarily biochemical in nature that was only active in certain conditions. - I'd need to know more about Gould's context because I certainly doubt he'd make an error that I'd pick up on. I need more problem info... - I would say that the trend towards complexity has a very simple answer: Since natural selection conserves traits necessary for survival it makes sense that a genome is primarily additive in nature. I'm sure Dr. Turell will lance this conjecture in the arse.

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