lucaspa

double post

1. Because most biofilms involve only a single species. Symbiosis requires more than one species. 2. Many biofilms don't involve quorum sensing. The biofilm forms simply because there are a lot of bacteria producing what the single bacteria produces. 3. Even in cases where quorum sensing triggers more than one species to make the biofilm, each species does just fine without the other when they are not in the biofilm. Symbiosis means that the species require each other. Must be some other Paul Lucas Some species do. Humans, for example. Notice that species that do exhibit such behavior also have adaptations in the individual for detecting cheating. Individuals that always help but never get help in return aren't going to last very long. OTOH individuals with the variations to detect cheating will do better. I'm not aware of reciprocal altruism going beyond species boundaries. That is, an individual of one species engaging in reciprocal altruism with a member of another species. There may be a few, but I haven't run across examples yet.

Part of the answer was in the Wiki article: "Many species within the Axolotl's genus are either entirely neotenic or have neotenic populations. In the axolotl, metamorphic failure is caused by a lack of thyroid stimulating hormone, which is used to induce the thyroid to produce thyroxine in transforming salamanders." If you want more details: http://www.ijdb.ehu.es/web/contents.php?vol=40&issue=4&doi=8877439 J. Huxley. 1920. Metamorphosis of axolotl caused by thyroid feeding Nature 104: 436. http://bio.research.ucsc.edu/~barrylab/classes/evolution/DEVO_EVO.HTM "Some salamanders remain in the larval form and this is due to an inactivation of the thyroxine cascade. Different species of salamaders have thyroxine mediated metamorphosis interrupted at various points in the cascade. In the axolotl, a neotenic salamander that breeds as an adult, you can simply feed it tissue with lots of throxine and it will transform to a terrestrial form."

As I read Geoguy, he was saying he didn't know much about shells but instead collected dino and mammalian teeth: "Here in Alberta I've collected Latest Cretaceous and Paleocene mammal teeth. ... I can 'find' the teeth, but after that defer to whomever." I'm not sure why he posted on this thread, since the post started with "I'll completely defer to you on primate evolution." and this thread has nothing to do with primate evolution. Perhaps he got the wrong thread and wanted your thread on the origin of primates?

ajb and swansont: we have two different constants being discussed. The OP was the cosmological constant or lambda. Immortal is talking about the fine structure, or alpha, constant. Alpha is NOT zero. Murphy eat all are claiming that their measurements of alpha exclude systematic errors that other people introduced because they did not use the internal checks Murphy et al. incorporated: "Other researchers have published results which suggest that alpha does not change. However Dr Murphy's work is the most detailed survey ever performed. He says that the internal checks in his method, which other research groups did not use, make this the most reliable measurement to date. " Ajb, lambda was originally introduced in the relativity equations by Einstein because gravity would collapse the universe. So lambda was originally arbitrarily set to a positive value that would counter gravity and keep the universe static. When it was found that the universe was expanding, lamba was no longer needed and was arbitrarily set to zero; it was never measured. The expansion was accounted for by the impetus from the Big Bang. The experiments looking at supernovae showed that the expansion of the universe was accelerating. The only part of the Einstein equations that could be used to account for this was lambda, which now had to be positive again to push the universe to expand.

Elas: I have spotted an elementary flaw in your analysis. You are misrepresenting Einstein. "The problem with Einstein's formula is that it gives the energy in the direction of movement (the energy on the compressed lead radial). If the speed is zero then E = m regardless of volume! " E=mc^2 does not give "energy in the direction of movement". It gives the relation of energy to mass. The formula is essentiall E=km where k = a constant. It turns out that the constant is c^2 (remember, the speed of light in a vacuum is constant in Relativity). Thus, the formula works if the particle is at rest. You start with a premise that is a mistaken notion of what the E = mc^2 equation is. Therefore, with a wrong premise, all your logic from that point is also going to be wrong. This is probably one reason that you can't get your paper published. BTW, there seems to be 2 "new theories" here, with 2 different web pages. I have confused the two upon occasion.

How do you know classical terms require a sponsor? Have you tried? If so, can we see the e-mail telling you that you must have a sponsor? You are still not looking at this the same way I am. You are looking for a sponsor to give validity to your paper. I'm having you look for a sponsor to get qualified review of your paper. There is no guarantee that anyone you approach is going to agree to sponsor your paper. The point is to get feedback as to why they won't sponsor your paper. IOW, a critique by a physicist. You can then either decide that your ideas are totally wrong or modify the paper to address the criticisms. Please walk us thru how the CLF model gave you the equation B1-(A2*B1) and also how CLF gave you the constant such that "a constant is used to reduce the scale to that of the wavelength (diameter) table so that the observations can be matched to the wavelength table without further adjustment. (The observations will only match in one position)." Without the constant it appears that the scale is way above that of the wavelength.

This gets back to basic physics and its influence on design by natural selection. Gravity is going to influence the possibilities of design. If you want to see such speculation, I suggest the science fiction of Poul Anderson; he was very good at creating different worlds and the evolution of plants and animals to inhabit them. Much lower gravity is going to mean that flight is easier and that more massive creatures will be able to fly. Higher gravity is going to impose restrictions on the size of creatures relying on exoskeletons and require more massive bones (and muscles) for endoskeletal land dwellers. Also, creatures are more likely to be low to the ground so that falls will be less likely to result in broken bones. It's fairly easy to speculate on generalities: simply look at the constraints and consequences of the physics. The particulars get messy because you then have to deal with the contingencies of evolution.

This is where patience needs to be exercised. I note from the original websites that even Murphy is being cautious about the changing constant: "Murphy is careful not to claim that the case is closed, and he says that nobody can really say that alpha varies until another type of experiment has confirmed it." You don't have "another type of experiment" yet. All 3 of your original websites are different sources to the same (and single) study. Also, the change is not very large: " By comparing these fingerprints with those obtained in experiments on Earth, he concludes that alpha has changed by about one part in two-hundred-thousand during the last 10 billion years. " My "not very large" is an understatement. BTW, both quotes are from http://www.physorg.com/news3665.html Just be patient and let the physicists fight it out. If Murphy et al.'s work is sound, there will be other studies. In the meantime, I would advise you not be an advocate of preliminary data that is not your own.

It was rigth there in my quote of your post: "Here in Alberta I've collected Latest Cretaceous and Paleocene mammal teeth. " The OP is talking shells and you are talking teeth. Separate things with different types of mineral. That will work, but be advised that ANY acid will dissolve HA. What you are relying on is that the limestone will dissolve in weak acid MUCH faster than will the HA. However, some HA will also be dissolved. The typical way to demineralize bones and teeth is 0.6 N HCl. However, a slower but gentler (to the proteins in the organic matrix) is citric acid (or acetic acid) + EDTA. I'm not sure what you are trying to say here. The information I have seen does say that inarticular brachiopods have shells of calcium phosphate (not hydroxyapetite, yet a 3rd mineral) while all other brachiopods have shell of calcium carbonate. "All of the previously viewed brachiopods are called articulate brachiopods---that is, they open their shells with a system of teeth and sockets that serve as a hinge that is controlled by adductor and diductor muscles that close and open the valves when the need arose. Inarticulate brachiopods, however, have no teeth or sockets and open their shells by an entirely muscular and ligament process. Articulate brachiopods have calcium carbonate shells whereas inarticulate brachiopods have calcium phosphate shells. " http://csd.unl.edu/fossils/nebrinvertstull.asp It appears that the "teeth and sockets" of articulate brachiopod shells are also calcium carbonate. If you have different information I would, of course, be interested in hearing it.

The mineral in teeth (and bones) is hydroxyapetite. Ca10(PO4)6OH2. Very different from any form of calcium carbonate.

That doesn't work. For one thing, neoteny usually works by the suppression of later developmental pathways. Teeth are an example of "isoforms" where you have one form replaced by another, similar, form later in development. Another example is the replacement of fetal hemoglobin by adult hemoglobin. Here: go to the library and find this paper: 1: Science. 1983 Sep 2;221(4614):921-7. Molecular and cell isoforms during development. Caplan AI, Fiszman MY, Eppenberger HM. Development proceeds by way of a discrete yet overlapping series of biosynthetic and restructuring events that result in the continued molding of tissues and organs into highly restricted and specialized states required for adult function. Individual molecules and cells are replaced by molecular and cellular variants, called isoforms; these arise and function during embryonic development or later life. Isoforms, whether molecular or cellular, have been identified by their structural differences, which allow separation and characterization of each variant. These isoforms play a central and controlling role in the continued and dynamic remodeling that takes place during development. Descriptions of the individual phases of the orderly replacement of one isoform for another provides an experimental context in which the process of development can be better understood. PMID: 6348946 [PubMed - indexed for MEDLINE] Related Links Functional coupling of creatine kinases in muscles: species and tissue specificity. [Mol Cell Biochem. 1998] PMID:9746324 Expression of muscle genes in the mouse embryo. [symp Soc Exp Biol. 1992] PMID:1341037 Expression of various NCAM isoforms in human embryonic muscles: correlation with myosin heavy chain phenotypes. [J Neuropathol Exp Neurol. 1992] PMID:1740671

That would be something quite different from neoteny. That would be "homology" or perhaps "isoform". What you tried to do was make an apple into an orange.

Yes, we have. http://www.theharbinger.org/articles/rel_sci/fox.html 1) depends on how you define "chemistry of life on earth". There are hundreds of amino acids, for instance, but life on earth only uses 20 or so of them. Could life on another planet use different amino acids in their proteins? Maybe to some extent, but remember that the simple chemical reactions to form amino acids are going to make some of them (the common ones among the 20 used in earth life) in a lot greater quantities than others. 2) again, depends on how you define "chemistry of life". 3) No. we can see this in variations on the various metabolic pathways among living organisms. There could easily be different metabolic pathways using different chemicals. For instance, we can see among earth living organisms different sources of energy: sulfides, sugars, etc. But those "complex compounds" don't form polymers. Only carbon and silicon can form long chain polymers of binding C-C or Si-Si. Any hereditary chemical for complex cells is going to have to be a polymer -- to be long enough to have genes -- and that means either carbon or silicon based. You also have to consider the role of water in biochemistry. Water isn't a passive solvent that just happens to be around. The chemical properties of water -- its polarity -- is an essential part of life. Before you post any more incoherencies on this board, why don't you get a copy of Lehninger's Biochemistry and read it. Once you have a foundation on the chemistry of life as we find it on earth, THEN you might be able to have some coherent thoughts on the subject of life that is not carbon based, or protein based, or nucleic acid based. Yes, there is evidence. You simply are either unaware of it or won't look for it. BTW, it is easy to "be confident in a hypothesis" if you have tested the hypothesis against evidence. Hypotheses are NOT "wild guesses". There are many hypotheses that are so well-supported that they have the status of "fact". Just one hypothesis with the status of fact is: RNA/DNA is the hereditary material in living cells.

No, you don't need that. There are lots of different ways to make amino acids and sugars, and lots of different ways to get amino acids to make first proteins and then protocells. The conditions are so flexible that it is virtually certain that somewhere on a planet one of the conditions would be present. It's obvious you didn't try "to see the validity" of associating Gibbs free energy with geological differentiation. Because there is no association and a moment's thought would have shown that. Do you just throw out scientific terms at random? It appears that way, because you show no comprehension of the terms you use. Because the non-metals section can form polymers thru covalent bonds. Metals can't do that. The association of metal to metal is ionic, not covalent. Such muddled thinking! First, let's separate chemistry from natural selection. Natural selection will act once chemistry has made an entity that can reproduce. Until then, natural selection can't work because natural selection requires heredity -- which in turn requires reproduction. Second, you need chemistry to get to the protocell. The protocell is not "chemistry of life" but rather the product of chemistry. Third, you have to remember the key role that water plays in the chemistry of life -- biochemistry. Not a problem. In order to be alive, an entity must exhibit ALL of the following criteria: metabolism, growth, response to stimuli, and reproduction. WOW, you do throw stuff out at random. Since you are obviously a lost cause for careful thought, the rest of the post is for the other members of the thread. Asexual reproduction is more efficient than sexual reproduction, but does not have as much variation among offspring. Recombination produces orders of magnitude more variation than mutation. Symmetry -- such as bilateral symmetry -- is not due AT ALL to electrochemical gradients within cells. It has to do with embryological development in multicelled organisms and gradients of morphogenetic proteins produced by cells. Electrochemical gradients within individual cells is a side effect of having proteins be the major component of cell membranes. Even modern cells have over 50% of their cell membranes as proteins, not lipids. You can make protocells out of only proteins and no lipids and they have cell membranes -- and electrochemical gradients. In fact, they have action potentials identical to nerve cells! 1. DNA/RNA exist because they can be faithfully replicated and serve as a template for directed protein synthesis. This is more efficient than proteins making other proteins in that each new protein will be identical -- coming from the same template. 2. Eukaryotes may have been first and prokaryotes are a simplification of them. This paper argues for a eukaryotes first approach: 9. AM Poole, DC Jeffares, D Penney, The path from the RNA world. J. Molecular Evolution 46: 1-17, 1998. Do a PubMed search on Penney and you will find other papers by him arguing for a eukaryote first approach. There is one very famous way in which pollution has opened a new metabolic pathway: use of nylon as food. 1. Birth of a unique enzyme from an alternative reading frame of the pre-existed, internally repetitious coding sequence", Ohno, S, Proc. Natl Acad. Sci. USA 81:2421-2425, 1984. Frame shift mutation yielded random formation of new protein, was active enzyme nylon linear oligomer hydrolase (degrades nylon) http://www.nmsr.org/nylon.htm

1. DNA does not "self-replicate". It needs an astonishing number of proteins for duplication. What DNA does is preserve the sequence of bases. 2. RNA can self-replicate! And, since there are ribozymes (RNA that acts like enzymes), there are actually RNA strands that can self-replicate. 3. There are also simpler nucleic acids, one of which is based on the sugar threose rather than ribose: 18. L Orgel, A simpler nucleic acid. Science 290: 1306-1307, Nov 17, 2000. 222/sciencemag.org/cgi/content/full/290/5495/1306 4. For "life" to exist, all you need are proteins. What you need DNA/RNA for is directed protein synthesis.

SOME biofilms involve more than one species. In this case, we are still dealing more akin to multicellular organisms where we have specialized organs. The quorum sensing is helping build the "organ" -- biofilm -- from several "tissue types" -- the species. It is more similar to building a liver from the ductal cells, blood vessels, stromal cells, and the hepatocytes. At least 6 different phenotypes (species) making one organ.

Again it is the confusion of "selection of" and "selection for". It is still the individual that is the object OF selection. But the particular allele that is being selected FOR. I'm not sure what you are referring to competition between genes and "passed on to the next generation more than other genes". As you said it, that would imply alleles that prevent copying of the other chromosome during meiosis so that only 1 chromosome of the pair is available in the sperm or ova. I haven't seen anything about that. I have seen papers about competition among sperm. In species where multiple males mate with a fertile female, there is competition between the sperm as to which one is going to fertilize the ovum. In those cases there are alleles that block sperm from other individuals. 12. Torgerson DG, Kulathinal RJ, Singh RS. Mol Biol Evol. 2002 Nov;19(11):1973-80. Mammalian sperm proteins are rapidly evolving: evidence of positive selection in functionally diverse genes. 10. Swanson WJ, Nielsen R, Yang Q. Mol Biol Evol. 2003 Jan;20(1):18-20. Pervasive adaptive evolution in Mammalian fertilization proteins.

Oh boy! 1. Species is the ONLY biological reality. Higher taxa are human ideas, not biological reality. Genera, families, orders, etc. are simply groups of species. Species cannot be precisely defined because evolution is true. Populations are transforming from one species to another over generations. We can see at generation 1 we have species A and at generation 1,000 we have species B. BUT, there is no defining moment where we can say species A became species B. That is, we CANNOT say "at generation 499 we have species A and at generation 500 we have species B". This means we cannot have a precise definition for "species". Whatever definition you use, you will always be able to find a population that is somewhere in-between. So, species are real. But we cannot make a precise definition of species. The issue was your thought that changing one gene from one allele to another made a new species. That doesn't happen, either. Speciation involves changes to more than one gene. 2. Individuals do NOT undergo speciation. Speciation happens to populations. I cannot emphasize that enough: evolution happens to populations. As an individual, I have no potential for speciation nor am undergoing speciation. I am born with the alleles I have and those cannot change during my lifetime. Only the population has its genetic composition change over generations. And no, not every population is in the process of transforming to a new species. Remember, 99+% of all species have gone extinct. That means that those species did not form a new species, but instead ended. The individuals in them were not intermediate to anything else. Also remember that, once a population is well-adapted to its environment, natural selection acts to keep the population the same and actually acts against change! It's called "purifying" or "stabilizing" selection. Yes, natural selection comes in 3 forms. Directional, purifying, and disruptive. Most people only consider directional selection and don't even realize the other 2 forms exist.

Go back and read Mayr again. Natural selection acts "on" the individual. It is the individual that is selected. That is, it is the bundle of genes that is the individual. The selfish gene theory doesn't work because of the reasons Mayr gave. No one is saying that Dawkins is against Darwinism, just that Dawkins is wrong in this particular area. The competition for scarce resources that is the "struggle for existence" takes place among individual organisms, not among single genes. Yes, individuals die, but so do alleles (forms of genes). Some alleles are eliminated from the population altogether and, thus, don't exist anymore. And yes, it is the fittest individuals that do the surviving and leave more copies of an allele (in their offspring) in the next generation. A single gene cannot survive; alleles only survive as members of a genome. Behavior is influenced by genes. And protein synthesis takes place in only a few seconds! That italics is wrong. No, you do NOT "know" that you have to choose the best one. Not in an evolutionary sense. You are imparting conscious choice of the individual in evolution, and Darwinism shows that is not the case. Again, that isn't what evolution says. We don't choose our alleles. We are either lucky enough to be born with a set of alleles that allows us to do well in the struggle for existence, or we are not. We don't choose novelty or novel alleles; we are born with them. It turns out that sexual selection is tied to survival traits. For a long time it was thought that sexual selection was distinct from survival traits, such that mate selection (such as female peacocks selecting for extravagant tails in the males) was actually picking maladaptive alleles. More recent studies have shown that, most often, alleles for mate selection are packaged with other alleles for adaptive traits. A paper looking this is: 3. E Pennisi, Females pick good genes in frogs, flies. Science 280:1837-1838, (19 June) 1998. Discusses recent studies that show how "bad" genes associated with male display are actually connected to survival genes in males, so that females actually pick survival traits. In frogs the descendents of "long callers" did better in every fitness test. And saving their relatives is WHY honeybees save the colony. They don't save the colony because it is the colony, but because the members of the colony are all siblings. In saving their relatives they are also saving the alleles that they have. That is Dawkins' view again, and it is fundamentally flawed. For the reasons Mayr stated. Also consider: 99% of all species have gone extinct -- which means their genes have gone extinct. If evolution is "for the good of the genes", then it doesn't work very well, does it? Dawkins made two fundamental errors: 1. Confused "selection of" and "selection for". 2. Ascribed consciousness to evolution. In this case, the "consciousness" is said to be in the genes. Unfortunately, what Dawkins did was write a book about his ideas for the lay public before those ideas were thoroughly tested by evolutionary biologists. Thus we have the situation now where we have a lot of lay people who took Dawkins at his word and think he was right. They haven't looked at the community of evolutionary biologists -- such as Mayr -- to see whether Dawkins really was correct. And he wasn't. Mayr didn't write for the lay public; he wrote for fellow evolutionary biologists. Only in his last book What Evolution IS did Mayr address a book to non-biologists. I strongly suggest you read that book, because some of your ideas on what evolution is are incorrect. I can see where you got them, but that doesn't change that you were misinformed.

And now I will agree with Martin. This is what I referred to as "abrupt" in that humans found that the cosmological constant (lambda) was not 0. Other types of measurements have confirmed the original measurements. I would like to emphasize this. There is a lot of discussion among physicists as to the cause of the nonzero lambda, but no consensus as yet. So we know lambda is not zero, but not why. Everyone, just be patient and wait while the physicists figure it out. It may take a while.

What do you think "neoteny" is? It is a very specific process in sexually reproducing multicellular organisms. In fact, it is limited to organisms that go thru extensive embryonic development! Therefore, it cannot possibly be used this way: "the molecular basis of life itself studied from such a neoteny perspective" There is just too much of life that is unicellular and a huge subset of that unicellular life that reproduces asexually for neoteny to provide any type of "perspective" for "the molecular basis of life itself".

Immortal, I'm afraid the paper doesn't show what you claim it does. It is an important paper for evolution, because it shows 1) increase in information, 2) formation of a new trait by duplication of genes. The key sentences in the Abstract are: "We show that RNASE1B has evolved rapidly under positive selection for enhanced ribonucleolytic activity in an altered microenvironment, a response to increased demands for the enzyme for digesting bacterial RNA. At the same time, the ability to degrade double-stranded RNA, a non-digestive activity characteristic of primate RNASE1, has been lost in RNASE1B, indicating functional specialization and relaxation of purifying selection. Our findings demonstrate the contribution of gene duplication to organismal adaptation" Look at the bold. That is the real key. Speciation requires reproductive isolation and this paper doesn't address that. There is no indication that RNASE1B causes reproductive isolation between duoc langur monkeys and any other species. There are studies looking at the genes that do change during reproductive isolation: 1. M Nei and J Zhang, Evolution: molecular origin of species. Science 282: 1428-1429, Nov. 20, 1998. Primary article is: CT Ting, SC Tsaur, ML We, and CE Wu, A rapidly evolving homeobox at the site of a hybrid sterility gene. Science 282: 1501-1504, Nov. 20, 1998.

Species don't get selected. Individuals do. IOW, the entire genome. I'll let Ernst Mayr explain the problem of Dawkins' reductionist version: "Much confusion about this problem can be avoided by considering two separate aspects of the question: 'selection of' and 'selection for'. Let us illustrate this with the sickle cell gene. For the question 'selection of' the answer is the individual who either does or does not carry the sickle cell gene. In a malalrial region the answer to 'selection for' is the sickle cell gene, owing to the protection it gives to its heterogenous carriers. When one makes the distinction between the two questions, it becomes quite clear that a gene as such can never be the object of selection. It is only part of a geneotype, whereas the phenotypes of the individual as a whole (based upon the genotype) is the actual object of selection (Mayr 1997). ... "The reductionist [Dawkins'] thesis that the gene is the object of selection is also invalid for another reason. It is based on the assumption that each gene acts independently of all other genes when making its contribution of genes to the properties of the phenotype. If this were true, the total contribution of genes to the making of the phenotype would be accounted for by the addition of the action of all individual genes. This assumption is referred to as the 'additive gene action' assumption. Indeed, some genes, perhaps even many genes, seem to act in such a direct and independent manner. If you are a male with the hemophiliac gene, you will be a bleeder. Many other genes, however, interact with each other. Gene B may enhance or reduce the effects of gene A. Or else the effects of gene A will not occur unless gene B is also present. Such interactions among genes are called epistatic interactions." Ernst Mayr What Evolution Is, pgs 126-127 Sorry, but "saving the colony" isn't the ultimate goal. Read EO Wilson's work. What the honeybee does is save its relatives. In terms of the Dawkins' reductionism you like, saving 2 siblings = saving yourself because those siblings will have the equivalent of your genes. The goal is saving their genes. It just so happens that the members of the colony are all siblings because the queen lays many eggs from one mating with a drone. Quorum sensing is for the benefit of the bacteria species. That is, within the species. There are 2 separate things happening with the V. fischeri bacteria. The bacteria are in symbiosis with the squid. However, the quorum sensing within the bacterial population is not symbiosis. Rather, the cost of producing luciferase by individual V. fischeri is greater than any benefit of glowing for the individual. Remember, there are V. fischeri that are free swimming. The benefit of glowing ONLY comes when the V. fischeri are concentrated in the photophore of the squid. And that is when quorum sensing comes in: the concentration of chemical is high enough to cause transcription of the gene for luciferase. So, the quorum sensing itself isn't symbiosis, but in this case aids the symbiotic relationship of V. fischeri and squid. Thus the quorum sensing happens within the V. fischeri to benefit the V. fischeri. Producing luciferase is part of the symbiotic relationship of V. fischeri to the squid. If you want to check my source: "Quorum sensing was first observed in Vibrio fischeri, a bioluminiscent bacterium that lives as a symbiont in the light-producing organ of the Hawaiian bobtail squid. When V. fischeri cells are free-living (or planktonic), the autoinducer is at low concentration and thus cells do not luminesce. In the light organ of the squid (photophore), they are highly concentrated (about 1011 cells/ml) and transcription of luciferase is induced, leading to bioluminescence." http://en.wikipedia.org/wiki/Quorum_sensing

There is no "law of evolution". Rather, what is being studied is what specific changes happened to specific genes to give the morphological traits that are visible via paleontology. Just a few papers that combine paleontology with molecular biology and developmental biology are: 2. RO Prum and AH Brush, Which came first, the feather or the bird? Scientific American, 84-93, March 2003. 3. Sawyer RH, Salvatore BA, Potylicki TT, French JO, Glenn TC,Knapp LWJ, Origin of feathers: Feather beta (beta) keratins are expressed in discrete epidermal cell populations of embryonic scutate scales. Exp Zool 2003Feb 15;295B(1):12-24 6. http://ajp.amjpathol.org/cgi/content/abstract/164/3/1099?ct 8. http://www.sciencemag.org/cgi/content/full/312/5770/97 JT. Bridgham, SM Carroll, J W Thornton Evolution of Hormone-Receptor Complexity by Molecular Exploitation Science 7 April 2006: Vol. 312. no. 5770, pp. 97 - 101 9. "Tracing a Backbone's Evolution Through a Tunicate's Lost Tail" Science vol. 274, pp 1082-1083, Nov. 15, 1996' Primary article is "Requirement of the Manx Gene for Expression of Chordate Freatures in a Tailless Ascidian Larvae" pp 1205-1208. 4. GJ Vermeij, Animal origins, Science 274: 525-526, 1996 (Oct. 25). The peer-reviewed article is GA Wray, JS Levington, and LH Shapiro, Molecular evidence for deep precambrian divergences among metazoan phyla. Science 274: 578-573, 1996 25 Oct. 8. AH Knoll, A new molecular window on early life. Science 285: 1026-1025, 13 Aug. 1999. Pushes origin of eukaryotes back a billion years to 2700 Ma. Original article is JJ Brocks et al. Archaen molecular fossils and the early rise of eukaryotes. Science 285: 1033-1036, 13 Aug 1999. Also look at the April 13, 2007 Science. Two articles there looking at the amino acid sequences of type I collagen from 2 fossils: a 60,000 year mammoth and a 65 Mya T. rex.