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Author | Topic: The Human Genome and Evolution | |||||||||||||||||||||||||||
Tranquility Base Inactive Member |
But what is this invisible boundary that delimits the human 'kind'. Read my post to sfs. For the purposes of this discussion I'm happy to concede that I can't prove a 'kind' difference here.
For example, to persue your argument from an evolutionary perspective, we might use chimps as an outgroup and test sequence homology between humans chimps and Neanderthals and find the latter closer to humans than the former. So we have: Humans __________________________(common ancestor)Neanderthals_______/..................../ Chimps______________________/ Agreed.
Presumably, you deny common ancestry between humans and ANY other animal, so the human lineage has to be essentially unbranched beyond the level of human 'kind'. Yes, but it's just a postulate.
And yet the existence of Neanderthals shows that it HAS branched *below* the level of kind. Hold on. I include Neandethal (and Erectus) as part of the human kind.
So I ask, yet again, what is it that somehow prevents branching *above* the level of 'kind' ? Can you clarify your use of above and below before I contine.
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Tranquility Base Inactive Member |
Mick
The links work presently. Maybe ICR was down? They just reveamped their site a month ago and I know they are still reorganizing stuff. But the links work now.
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Tranquility Base Inactive Member |
EZ
Well I just assumed that at some point the 3 must have shared as common ancestor. Starting with the lineage that ultimately led to humans, I am simply assuming that Neanderthals diverged from this lineage later than chimps did, given they are obviously closer to humans. I am not an expert on hominid phylogeny either, I was just trying to make the point that once you accept branching lineages, you may as well accept that more and more branches occur all the way back. There is no known mechanism that could ensure the eternal integrity of a 'kind', however defined, because this would imply no branching had ever occurred above this level. I'm still trying to understand what you're saying. I'll try and paraphrase what you're saying: because trees include kind members AND kinds themsleves therefore kinds are invalidated as a concept. Is that what you're saying?
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hitchy Member (Idle past 5117 days) Posts: 215 From: Southern Maryland via Pittsburgh Joined: |
Sounds to me like he is saying what the scientific community has been saying all along about "kinds"--it is a useless term when used to classify organisms. There would be no branching resulting in a new "kind" if they were individually created to begin with. If one "kind" branched off into another "kind", then at what levels are these "created kinds"? At what point is the "weasel kind" differentiated from the "otter kind" and the "ermine kind" and the "fisher kind" and the "ferret kind"? Or all these all "kind members" of the "mustelid kind"? Or "kind members" of the "carnivore kind"? Where does the classification "kind" end?
Also, if I can be indulged to literally look at the Holy Bible (sorry, but the NRSV version is the only one I have on hand), it seems that the "creator" (or creators, if you look at Gen 1:26--Let us make humankind in our image, according to our likeness) set things a little ambiguously with the whole "living creatures of every kind". Why are we splitting hairs trying to delimit an openly ambiguous term such as "kind"? Another tidbit, apparently the only plant "kinds" the "creator" created were the seed plants. What about the Bryophytes and the seedless vascular plants? Of what "kind" are they? They are significantly different enough from the "seed bearing kind" to merit a "kind" of their own worth mentioning. Same for the bacteria, archaebacteria, and protists that aren't specifically mentioned!?! With what we can gather from the Holy Bible, wouldn't it make more sense to say that whoever wrote this section only had a limited knowledge of the flora and fauna constricted to the immediate surroundings of the authors' locale? So, the record here is incomplete, and although I applaud the time and effort, wouldn't it make more sense to follow the apparent evidence and not try to restrict what we see in nature to such a narrow view? Take care.
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Wounded King Member Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
Agreed. Whjen I say 'fly' I'm including all flies, not just drosophila. Well unless you have secretly sequenced the genomes of all 'fly' species you are making this statement based upon a very small sample, pretty much just Drosophila really. So your fly/mosquito specific genes are really only A. gambiae/D. melanogaster specific, to the best of our knowledge so far.
Sure. But my point is if we don't find the 1000-odd mosquito-specific genes anywhere else then it means these appeared just for the mosquito very early (given amber fossils). This doesn't neccessarily follow. The 1000 'specific' genes need not be directly related to the gross morphological/ anatomical characteristics preserved in Amber. TTFN, WK
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EZscience Member (Idle past 5153 days) Posts: 961 From: A wheatfield in Kansas Joined: |
TB writes: I'm happy to concede that I can't prove a 'kind' difference here. Then there is no point in arguing for retention of the term or discussing the matter further.It is just providing you biblical gratification without providing us with any scientific utility. TB writes: For the purposes of this discussion, I am quite happy to conceded that I can't prove genetically that mankind didn't evolve from other primates. So what happened to your precious human ‘kind’ created in God’s image ?
TB writes: It's very consistent with the idea that God created a series of genomes that have since diverged primarily though gene loss. But there is plenty of evidence for information *gain* in genomes, like for example in the article I cited back in message 56 of this thread. Plenty of other examples too. If divergence occurs primarily due to loss of information (genes), then why is it that we see organisms becoming more complex over time in the fossil record, rather than less? There is simply no evidence that some hypothetical initial ‘set’ of genomes were created. How, in your slippery view of the world, would we distinguish a ‘created’ genome from one that evolved ? When I asked if you deny branching of the human lineage, you said:
TB writes: Yes, but it's just a postulate. Sorry, that’s not good enough. Without some sort of testability, postulates are just pipe dreams. The preponderance of the evidence points in the other direction, namely that the human lineage is one branch of the primate branch of the mammal branch which, itself, is only one branch of many others on a much larger tree. The idea of a 'kind' has absolutely no utility in this conceptualization.
TB writes: Hold on. I include Neandethal (and Erectus) as part of the human kind. Fine. But the basic morphological differences between Neanderthals and modern humans (and other lines of evidence, I suspect) strongly suggest they would have been genetically incompatible. But I guess this distinction doesn’t matter to your definition of ‘kind’. Speciation is of no real consequence to your view of evolution because your imaginary immutable 'kinds' continue their evolution in parallel and can never be traced back to a common ancestor. So I ask you, yet again, once you have separate gene pools what can possibly limit the degree of divergence of one organism from another ? Answer: nothing. So there is nothing that can possibly maintain the integrity of your 'kind' within any of the implied limits.
TB writes: Can you clarify your use of above and below before I contine. I meant that if the human lineage branched into Neanderthals 'below' the point where it became recognizably 'human' (which it did, despite your insistence in considering them the same ‘kind’), then what prevents the human lineage from being one branch diverging from another lineage (above the level of human ‘kind’)? But now, from the above quotes, it seems you have conceded (1) you cannot provide a functional definition of how a ‘kind’ is delineated and held immutable and (2) you accept that you cannot disprove genetic evolution of humans from primates. So what earthly (scientific) use is your nebulous, biblically-derived concept of 'human kind'?I think I can rest my entire case at this point.
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mick Member (Idle past 4986 days) Posts: 913 Joined: |
EZ writes: TB writes: It's very consistent with the idea that God created a series of genomes that have since diverged primarily though gene loss. But there is plenty of evidence for information *gain* in genomes
Just to give some details for TB, here is gene number for a variety of species. Gene number appears to increase rather than decrease with time. Genome complexity appears to increase rather than decrease with time (measured by gene density, inverse of amount of non-coding sequence per genome) species, number of genes, gene densityHomo sapiens, ~30,000 genes, 1 gene per 100,000 bp Rattus norvegicus, ~30,000 genes, 1 gene per 100,000 bp Mus musculus, ~30,000 genes, 1 gene per 100,000 bp Drosophila, 13,600 genes, 1 gene per 9,000 bp a plant, 25,500 genes, 1 gene per 4000 bp roundworm, 19,100 genes, 1 gene per 5000 bp baker's yeast, 6300 genes, 1 gene per 2000 bp a bacterium, 3200 genes, 1 gene per 1400 bp
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Wounded King Member Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
That doesn't seem to show any increases with time, in fact I can't see anything indicative of time anywhere in that data.
I know what you mean, but in terms of time, you've got nothing. In fact in the only really meaningful measure of evolutionary time, i.e. generations, you might argue that those species with the longest evolutionary history have the least genes. TTFN, WK
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Wounded King Member Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
Leaving aside the 'time' component, these data could only argue for increases in genomic content if both sides agreed that the starting point was a common ancestor. If TB is arguing that there were seperate ancestors for the Yeast Kind, bacteria kind, rodent kind etc..., then we don't have much counterargument based on this data. The difference in bacterial and human genomes only looks like the result of a process of increase if you accept that man evolved from something like a bacteria.
TTFN, WK This message has been edited by Wounded King, 07-11-2005 12:39 PM
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mick Member (Idle past 4986 days) Posts: 913 Joined: |
wk writes: I know what you mean, but in terms of time, you've got nothing. In fact in the only really meaningful measure of evolutionary time, i.e. generations, you might argue that those species with the longest evolutionary history have the least genes. I think I see what you're getting at. But to show an inverse relationship with time (i.e. gene loss) wouldn't it require humans, mice and rats to be older than bacteria and yeast? I may be mistaken here, but I think the general trend is clear. Mick added in edit:
wk writes: Leaving aside the 'time' component, these data could only argue for increases in genomic content if both sides agreed that the starting point was a common ancestor. Yes, the 'time' component necessitates us accepting that the species here appeared at different times, not simultaneously. If they all appeared at the same time, then there IS no time component. For this reason one cannot argue that genes are lost over time, while arguing for simultaneous origin. The hypothesis that gene number declines over time necessitates the belief that species arise from one another (otherwise, what does the decline mean?). Mick This message has been edited by mick, 07-11-2005 12:49 PM
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Wounded King Member Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
I think I see what you're getting at. I'm not sure that you do. Where is your time factor? In what way are the bacterial genomes that have been sequenced any 'younger' than the Human ones? Did you go back in your time machine to 1 billion years ago and scoop some up?
But to show an inverse relationship with time (i.e. gene loss) wouldn't it require humans, mice and rats to be older than bacteria and yeast? Nope, because bacteria and yeast have massively shorter generation spans compared to humans, mice etc.... Lets look at a hypothetical example. We have an ancestor of the man kind with 60,000 genes and an ancestor of the bacterial kind also, for reasons of equality, with 60,000 genes. We assume that the bacteria have a generation time of 3 hours and that humans have a generation time of about 12 years. If each kind loses genes at an equivalent rate, say 1 gene every 1000 generations, you can see that after 100 years you are going to have a bacterial 'kind' with a distinctly reduced genome compared to the human 'kind'. So even allowing all ancestral kinds to have been produced de novo at the same instant you could see such a pattern as the result of gene loss, at least logically if not biologically. TTFN, WK
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EZscience Member (Idle past 5153 days) Posts: 961 From: A wheatfield in Kansas Joined: |
I agree that generation time is the meaningful unit of time to be considered when thinking about relative rates of evolutionary change in various species, but surely if you accept the basic fossil record with its time line of geological stratification then this means that all the most complex organisms appeared relatively late, while simple ones were around the longest (e.g. the Archaebacteria). Despite their shorter generation times and consequently ample opportunity to evolve complexity, they have not. They simply happen to occupy niches that favor simple body plans and select against increases in complexity. I doubt you would be willing to argue that simple organisms have frequently evolved from more complex ones, which is the essence of what we would expect if god created a fixed number of 'kinds' which then diversified through speciation in parallel, but with an overall trend toward loss of genetic information, albeit occurring at different rates in different lineages. So Mick's point about gene density being greater in the more complex organisms does have an implicit time component when viewed in the context of other evidence that most of us, and I suspect you also, accept.
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Wounded King Member Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
Despite their shorter generation times and consequently ample opportunity to evolve complexity, they have not. So you aren't a fan of obscure notions such as common descent then? I didn't have you pegged as a special creationist.
I doubt you would be willing to argue that simple organisms have frequently evolved from more complex ones I think there are a number of obligate parasites, not to mention endosymbionts, from which a case might be made but I would certainly agree that it is the exception rather than the rule.
which is the essence of what we would expect if god created a fixed number of 'kinds' which then diversified through speciation in parallel, but with an overall trend toward loss of genetic information, albeit occurring at different rates in different lineages. Well now you are making the same mistake that TB did a couple of posts ago and that Mick seemd to be making. A consistent morphology doesn't have to mean a consistent genotype. I would certainly expect a high degree of conservation in large number of developmental genes important in establishing morphology, but that still leaves the potential for a whole lot of genome for god to go hiding in, especially if it has all been handily lost beyond recall. Just consider the many possibilities inherent in having a large panel of genes whose only job is to repress the function of genes which are reqired for later morphological developments of a lineage rather than an individual. Genetic complexity need not be reflected in morphological complexity, although there certainly seems to be a correlation in those species that we find extant nowadays. I'm perfectly happy to assume that this trend holds good going back in evolutionary time, but I suspect that a number of creationists might not be.
So Mick's point about gene density being greater in the more complex organisms does have an implicit time component when viewed in the context of other evidence that most of us, and I suspect you also, accept. That is why I said I knew what he meant, but unfortunately he didn't say what he meant and a lot of the assumptions that inference is based on are going to be less than convincing to many creationists. TTFN, WK P.S. I'm not just trying to be difficult, honestly.
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EZscience Member (Idle past 5153 days) Posts: 961 From: A wheatfield in Kansas Joined: |
WK writes: So you aren't a fan of obscure notions such as common descent then? I didn't have you pegged as a special creationist. Point well taken. Some primitive Archaebacteria obviously did evolve complexity, while those remaining in the ancestral niches did not. (I should have stated that better). So you get some lineages evolving complexity while others do not, but you don't usually see decreasing complexity as an overall trend in any lineage.
WK writes: ...that still leaves the potential for a whole lot of genome for god to go hiding in But exactly how would he hide there and what on earth could possibly constitute evidence of 'genomic creation' as opposed to evolved sequences, whether they are coding or non-coding ? I argue against the concept of created kinds because there is no way to objectively distinguish one kind from another and no imaginable, let alone demonstrable, mechanism for preserving the boundaries. The same applies to created genomes, that are now apparently allowed to diversify and speciate within invisible boundaries that only god can recognize.
WK writes: Genetic complexity need not be reflected in morphological complexity, although there certainly seems to be a correlation in those species that we find extant nowadays. I'm perfectly happy to assume that this trend holds good going back in evolutionary time, but I suspect that a number of creationists might not be. So it falls upon creationists to come up with some kind of evidence for this apparent 'devolution' of living things they seem to be postulating.
WK writes: ...a lot of the assumptions that inference is based on are going to be less than convincing to many creationists. I have given up trying to 'convince' creationists. They will see god in a genome as fast as a Latin American will see the virgin Mary in a taco. I will settle for demonstrating they have no workable scientific mechanisms or testable theories, nor can any functional insights be derived from their musings.
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GDR Member Posts: 6202 From: Sidney, BC, Canada Joined: Member Rating: 1.9 |
EZScience writes: I have given up trying to 'convince' creationists. They will see god in a genome as fast as a Latin American will see the virgin Mary in a taco. I will settle for demonstrating they have no workable scientific mechanisms or testable theories, nor can any functional insights be derived from their musings. I'm not sure that is fair. It seems to me that science can only tell us how we evolved; it cannot tell us whether or not there is any metaphysical intervention or not. Isn't it just as much a matter of faith to say that there is only random selection, with no divine intervention, as it is to say that evolution is guided by a metaphysical intelligence? There is no empirical evidence for either conclusion, so our opinions on this are formed from philosophy, or theology, but not science. This message has been edited by GDR, 07-11-2005 03:16 PM
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