Sorry about the delay; life intruded there for a bit.
"Okay, you've supplied a believable mechanism by which changes might occur." It is important to note that this is not just "might occur"——we see this happen in populations, our own and others.
Also, any hypothesis worth consideration makes testable predictions. This one, that chromosome count changes lead to species separation, predicts that organisms that reproduce asexually would have greater speciation, as they don't have to worry about matching them up again. Also, that the greatest genetic diversity would be self-fertilizing plants, as they would have both the male and female contribution from the same parent, and thus the same chromosome count. Both of these predictions match what we observe in nature.
In fact, humans have about three-billion base pairs in their DNA. There are species of amoeba with more than 600 billion. And within the human cultivation of plants on this planet, wheat has separated from etter grass; there was a chromosome duplication, and the two can no longer interbreed at all. But wheat and etter grass have greatly diverged since then; this has been in a relative eyeblink in history. We don't get much fossils of grassy plants, or in fact much fossils at all; but fortunately we could see this happening historically.
"And what about that pesky fossil record? You seem to imply that it really isn't much good for proving anything."
Well, the fossil record is sporadic at best, although there are literally billions of microfossils; these tend to preserve better, but are unsatisfying to laypersons. But, nevertheless, what we see is entirely consistent, with good predictability. For example, we had very early tetrapods, still aquatic, from 370 million years ago, then a gap, then a better, more land-capable tetrapod from about 330 million years ago, with many changes. We had nothing from that gap in the Devonian period of this creature type.
Just months ago, we found a critter from halfway between——350 mya——and it looks just like what one would predict from the ones before and after. Transitional.
"Lack of evidence does not prove any theory." True. And neither does evidence. Science doesn't work that way; one can never prove a theory. It simply works. It is possible to prove it wrong, or incomplete——and at this task creationist have labored for a hundred plus years without success. The theory of evolution (TofE)is refined at the edges, and scientists are motivated to make this refinements seem "revolutionary". But the core has remained stable, and all of modern biology and medical research is built on this core. By Christians, Hindu, atheists, and all sorts of different philosophies.
The results speak to all of these people. In spite of the vehement disagreements that people (especially scientists!) seem prone to, the scientists working in these fields are way over 99% agreement on the TofE.
You ask what the chances are. They are very small indeed. But only those (and neutral changes) get preserved, and nature has large amounts of population and time to play with.
The moth study was reported in an issue of Science a few weeks ago.
And mutations (the same mutation, anyway) don't generally occur simultaneously with a population; that's not necessary at all. Once you realize that, the "odds" change dramatically.
Do you accept that mankind and chimpanzee share the same ancestor?
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timeasmymeasure
no subject
Date: 2002-11-19 03:56 am (UTC)"Okay, you've supplied a believable mechanism by which changes might occur."
It is important to note that this is not just "might occur"——we see this happen in populations, our own and others.
Also, any hypothesis worth consideration makes testable predictions. This one, that chromosome count changes lead to species separation, predicts that organisms that reproduce asexually would have greater speciation, as they don't have to worry about matching them up again. Also, that the greatest genetic diversity would be self-fertilizing plants, as they would have both the male and female contribution from the same parent, and thus the same chromosome count. Both of these predictions match what we observe in nature.
In fact, humans have about three-billion base pairs in their DNA. There are species of amoeba with more than 600 billion. And within the human cultivation of plants on this planet, wheat has separated from etter grass; there was a chromosome duplication, and the two can no longer interbreed at all. But wheat and etter grass have greatly diverged since then; this has been in a relative eyeblink in history. We don't get much fossils of grassy plants, or in fact much fossils at all; but fortunately we could see this happening historically.
"And what about that pesky fossil record? You seem to imply that it really isn't much good for proving anything."
Well, the fossil record is sporadic at best, although there are literally billions of microfossils; these tend to preserve better, but are unsatisfying to laypersons. But, nevertheless, what we see is entirely consistent, with good predictability. For example, we had very early tetrapods, still aquatic, from 370 million years ago, then a gap, then a better, more land-capable tetrapod from about 330 million years ago, with many changes. We had nothing from that gap in the Devonian period of this creature type.
Just months ago, we found a critter from halfway between——350 mya——and it looks just like what one would predict from the ones before and after. Transitional.
"Lack of evidence does not prove any theory."
True. And neither does evidence. Science doesn't work that way; one can never prove a theory. It simply works. It is possible to prove it wrong, or incomplete——and at this task creationist have labored for a hundred plus years without success. The theory of evolution (TofE)is refined at the edges, and scientists are motivated to make this refinements seem "revolutionary". But the core has remained stable, and all of modern biology and medical research is built on this core. By Christians, Hindu, atheists, and all sorts of different philosophies.
The results speak to all of these people. In spite of the vehement disagreements that people (especially scientists!) seem prone to, the scientists working in these fields are way over 99% agreement on the TofE.
You ask what the chances are. They are very small indeed. But only those (and neutral changes) get preserved, and nature has large amounts of population and time to play with.
The moth study was reported in an issue of Science a few weeks ago.
And mutations (the same mutation, anyway) don't generally occur simultaneously with a population; that's not necessary at all. Once you realize that, the "odds" change dramatically.
Do you accept that mankind and chimpanzee share the same ancestor?
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