Talk:Evidence of evolution

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I'd like to know, once and for all, whether the peppered moth is considered evidence for evolution. If it's not evidence but "just an example", then what is it an example of?

Jon Wells says, "When asked to list the evidence for Darwinian evolution, most people--including most biologists" give the peppered moth as an example. I've asked at Wikipedia whether what this means. I hope my stalkers don't dismiss the question simply because I cross-posted it. If the moth's change in distribution of light and dark varieties is cited by scientists (or at lease educatiors) as evidence of evolution, then I will include it in CP's evidence of evolution article. If not, I won't; it's that simple. --Ed Poor Talk 13:45, 9 January 2009 (EST)

First I would like to point out that I really dislike the use of the peppered moth as an example. The question that has to be asked first is what do you define as evolution? If it is a phenotype change in a population then yes, the peppered moth is an example. If it is speciation then no, the peppered moth is not an example. Some creationists will accept the peppered moth as an example of microevolution. I personally would use the Nylon-eating bacteria as an example.--Able806 14:08, 9 January 2009 (EST)
Well, that's my point: Are evolution educators using a good example of evolution as "evidence for evolution" or not? I'm trying to settle the matter of whether the best known of the Icons of Evolution is a valid example of bias. I figure either:
No one uses the moth as "proof" of evolution - so Wells has no case here; or,
Only a few educators or scientists use the moth as proof of evolution - so Wells is making a mountain out of a molehill; or,
This is one of the ten most common "proofs" of evolution - so it matters whether the example is proving anything or not.
If both varieties existed before the soot pollution, then how is it an example of microevolution? I thought "evolution through natural selection" refers only to new forms of life being caused to come into existence.
(Or does "evolution" sometimes also mean "changes in distribution of existing organisms"? If so, why would anyone try to prove or disprove that?) --Ed Poor Talk 14:35, 9 January 2009 (EST)
Very good points. I often remember the fact that most high school biology teachers either minored in biology in college or they had a couple of bioclasses with their masters. In either case their exposure to evolutionary theory is very limited and I would not refer to them as evolution educators. I know for a fact that the Peppered Moth is not used as an example in most college bio-major classes, due to better and more current examples. The use of the Peppered Moth may just "date" the instructor, lol. I would say that Wells is making a mountain out of a mole hill.
As for your last question "does "evolution" sometimes also mean "changes in distribution of existing organisms"?" yes it does. This is one of the driving forces in evolution as population distribution directly effects gene dispersion. Both varieties of moth did exist before the soot pollution, if anything the peppered moth example shows population shift due to natural selection (moths easier to see).--Able806 14:54, 9 January 2009 (EST)

I'm confused (but don't worry: that's my normal state when I first start learning about something). Did you just say that "changes in distribution of existing organisms" are a cause of evolution? (I thought they are a result.)

More to the point, is a "population shift" the same as a change in the distribution of existing varieties of a species? If so, is this considered part of "the theory of evolution" or simply a general principle of ecology?

  • I have seen evolution defined as "any change in the frequency of alleles within a gene pool" [1]; but also as,
  • changes in populations that are ... inheritable via the genetic material from one generation to the next

If glaciers come down from the North Pole over a period of tens of thousands of years, this will change the distribution of varieties and species of plant and animal life. But when they melt later on (see interglacial), the same distribution pretty much comes back. Are any new varieties or species created during or because of this?

What I'm really getting at is a way of making the theory of evolution falsifiable. For it to be distinguished from pseudoscience, there has to be some aspect of it which (proponents admit?) which makes a testable prediction. Or which at least says, "If the theory is true, then we will see X in the fossil record."

Then if X is produced, we can say that evolution is consistent with reality. But if we can't produce X, we might be justified in doubting evolution.

One "X" we're all looking for is an modern example of evolution. If by "evolution" we mean the appearance of a new variety or species. If there were no dark varieties of the peppered moth 200 years ago, but soot pollution brought it into being, this might prove something (but see also breeding). --Ed Poor Talk 15:25, 9 January 2009 (EST)

Sorry about the delay in response, weekend:). "Changes in distribution of existing organisms" is not caused by evolution but is one of evolution's causes. You are correct a population shift is a change in the distribution of existing species. This would be a general principle of ecology that has an impact on evolution.
Now to answer the glacier question, very well put if I might add. If the returning species are not significantly genetically changed upon their return then they would be either a new variety or species. However, if the organisms do return with significant genetic changes to cause speciation then it could be evidence of evolution. The problem is a matter of time for the genetic changes to cause a shift in the population.
As for looking for "X". I know that often scientists propose the use of the fossil record for falsification of evolution, which many creationists say is faulty. I prefer another approach that is easier to understand, but requires a basic understanding of biochemistry. All living organisms have biochemical processes. Many lower life forms have the basic biochemical pathways found in every higher-level organism. Each species has different biochemical pathways that contribute to their uniqueness. Now most of these higher level pathways use the primitive pathways to function, like the foundation of a skyscraper. Many of these pathways need to be in a certain order to allow for the end biochemical pathway to function. See what I am getting at, like organisms share more similar biochemical pathways than unlike organisms. So a way to falsify evolution (the theory of common descent) all we would have to find is a similar if not same biochemical pathway found in one organism, but not found in any of its related organisms, and find the same or similar pathway in a totally non-related organism. For example, we find a pathway in Humans and a similar pathway in the raven, but not in any reptiles, birds, and we do not find this biochemical pathway in any other mammals. This would falsify evolution since in theory for Humans and birds to share a biochemical pathway it would have to develop in a common ancestor of both humans and birds or precursors found in the linage of humans and birds. Now there is a difference between a pathway and process, a biochemical pathway is a series of biochemical processes. I point this out since the chance of a new pathway coming into existence in two non-related organisms is pretty low (almost zero I would say) but a biochemical process is more common.
If what I described was unclear please let me know, I will try to make it clearer.--Able806 09:25, 12 January 2009 (EST)