Can Chromosome Counts Change?

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Back to the question you couldn't answer - how would you tell the difference between two proteins from the same family and two from a different family?

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How? By analysing the given protein sequences. I imagine you could tell the difference by running a computer comparison of the protein sequences-such as Genome Analysis: Search for a Largest Protein FamilyThis would be the experimental/statistical method of determining whether they would be in the same family.

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How come you're still talking about "created kinds" when you couldn't even tell me what they are?

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Well... "kinds" could possibly be along the lines of, in the kingdom/phylum/class/order/family/genus/species as somewhere around the family or order level. Ie, zebras, horses, donkeys, etc. (Technically nowadays I think taxonomists have added 3 domains as a level above kingdom... but not that it matters)I'm going to be going on a holiday for a while so I won't be able to post until I come back [This message has been edited by blitz77, 01-10-2004]

That's not really an answer. What would you look for in your analysis? What features identify protiens that share or do not share descent? How would you tell the difference between protiens sufficiently removed from the same family and protiens from two different families, if they're equally different in both cases? But those are arbitrary, human-imposed classifications, not organizational levels found in nature. So they can't be "kinds". For the "kinds" argument to have merit it has to be based on something actually found in nature.

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That's not really an answer. What would you look for in your analysis? What features identify protiens that share or do not share descent? How would you tell the difference between protiens sufficiently removed from the same family and protiens from two different families, if they're equally different in both cases?

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That is what phylogeny and systematics is for. If they're equally different in both cases, well, which would evolutionary theory support? Such and such proteins were from a common ancestor, thus are in the same family... If they were equally different, then I'd say there's either something wrong with evolution or possibly horizontal gene transfer had something to do with it.

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But those are arbitrary, human-imposed classifications, not organizational levels found in nature. So they can't be "kinds". For the "kinds" argument to have merit it has to be based on something actually found in nature.

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That may be true, but taxonomists try to modify and use these classication systems to help conform with evolutionary relationships. Why else are there always so many arguments for such-and-such an organism to be defined as within or not within a given clade?

But of course the evolutionary view is that all protiens are ultimately from the same ancestor. The argument is because the classification systems are arbitrary. If they were an actual phenomenon of nature, there'd be no argument whatsoever.So what's a kind, again? How do I tell if two organisms are in the same "kind" or not?

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But of course the evolutionary view is that all protiens are ultimately from the same ancestor.

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But the evolutionary view is also that all hominids came from the same ancestor, zebras/horses/donkeys from the same ancestor, the cat family. But your point here is moot; evolutionary theory would still have to have only one possible "family" from which the protein evolved, not two. Of course, with evolutionary theory the two possible "families" were once together....

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The argument is because the classification systems are arbitrary. If they were an actual phenomenon of nature, there'd be no argument whatsoever.

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Could that possibly be because the proposed evolutionary lines are also arbitrary and being debated? Of course, it couldn't be....

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So what's a kind, again? How do I tell if two organisms are in the same "kind" or not?

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Well, one method is from the fossil record-paleontology. Horses, zebras, donkeys with a common ancestor. If they all descended from the same organism, then they're one "kind". If they happen to go further, to say, all mammals... then they'd still have with the creationist definition be a "kind", even if it went all the way to bacteria-so that would be one method of falsifying this theory. So if it went all the way to bacteria, or a common plant/animal ancestor as a "kind", this YEC theory would obviously be wrong.[This message has been edited by blitz77, 01-10-2004]

Arbitrary? Maybe you need to look that word up, maybe? The proposed evolutionary lines may be theoretical in some cases, but they're hardly arbitrary. They're based on evidence, on natural features and genetic similarities.I mean, is there anything arbitrary about you being descended from your parents? Hardly.If you think this is a substantial rebuttal to what I'm saying, then you clearly don't understand what I'm telling you. Yet, you're unfazed by the large-scale continuity found in the fossil record that proves exactly that?Again we reach the inescapable conclusion - if there is such a thing as a "kind", there's only one of them: life.Honestly your answer isn't very helpful at all. Let's try a more practical excercise. Take any two animals that you think belong to different kinds and explain to me, without recourse to arbitrary taxonomy, how you know that they're of two different kinds - that is to say, they share no common ancestor.

Could you elaborate a bit? Are horse, donkeys and zebras one kind as far as you are concerned?Are birds and reptiles? Reptiles and mammals?

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Common sense isn't[This message has been edited by NosyNed, 01-10-2004]

Hi Rrhain,
Please note what I said after that statement as well. However, I will wrack my brain to remember the reference. By the way, I hope you aren't implying that genotype always predisposes an organism to a specific phenotype?

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But... but... that begs the question-how did the first hox gene arrive?

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In both cases, I have off the top of my head provided examples where novel gene families arise from a precursor...precisely what you claimed does not happen. Your answer? Typical, you switch to claiming that because it does not demonstrate how the first gene arose it is a non-answer. Ironic that you bring up Tranquility Base...he had the same problem with logic. However, we can trace back original protein development as Taz suggested by searching for both sequence and functional homologs in single cell organisms which do not for example in the case of hox genes, need segment polarity determination, or in the case of endogenous retroviruses, by their relationships with other retroelements particularly exogenous retroviruses for exampleKim HS, Lee WH.
Human endogenous retrovirus HERV-W family: chromosomal localization, identification, and phylogeny.
AIDS Res Hum Retroviruses. 2001 May 1;17(7):643-8.in the case of homeotic gene regulation (not directly Hox gene origins but origins of their regulation) one can find homologs in yeastTamkun JW, Deuring R, Scott MP, Kissinger M, Pattatucci AM, Kaufman TC, Kennison JA.
brahma: a regulator of Drosophila homeotic genes structurally related to the yeast transcriptional activator SNF2/SWI2.
Cell. 1992 Feb 7;68(3):561-72.and wrt hemoglobinHardison R. Related Articles, Links
Hemoglobins from bacteria to man: evolution of different patterns of gene expression.
J Exp Biol. 1998 Apr;201 ( Pt 8):1099-117. Review.Particularly the last paper focuses on origin and evolution of hemoglobin from an ancient precursor into the mutlifunctional family present in bacteria to humans.So your first point that novel proteins or protein familes cannot evolve is patently wrong. And your second point about where specific proteins come from originally is also possible to address using methodological naturalism as opposed to undefined terms like "kinds" or appeals to god/god's/pink unicorns and other mythological constructs.

I think that perhaps a better, certainly an alternative, way of answering the question 'how did the first hox gene arrive?' is to look not at the higher level of regulatory signals such as Brahma but at its evolutionary precursors amongst the abundant homeobox containing proteins, especially as Brahma is only a drosophila relative of the SWI2/SNF2 containing proteins a family which itself covers an awful lot of ground.A homeotic gene is a very vague functional description, only saying what the gene does and nothing about what it is. The homeobox genes however have very specific structural features which allow their DNA binding activity and their role as transcriptional regulators involved in a huge variety of areas from the aforementioned polarity/ patterning to cell cyle regulation. The real question is possibly that of how particular domains, such as the various DNA binding and regulatory domains, first evolved, this is always going to be highly speculative however due to the huge tracts of evolutionary time since those initial genes/proteins were extant. As soon as a few of these domains appeared then the possibilities for combining and domain swapping and consequently varied function increased enormously.