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24HourForums.com > Supported Forums > Brian's Science & Nature Shack > 6 lines of evidence - evolution ain't going away |
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24HourNut Administrator  Body pillows rock!
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I got this from another site, it's not my work. 1) ERV's - endogenous retroviral insertions Retroviruses infect host cells by transforming their RNA into DNA via reverse transcriptase. It is possible for this process to "go wrong" and for retrovirii to infect a cell without otherwise damaging it, thereby leaving behind its genetic material. In short, that retroviral DNA becomes a part of the host cell's DNA at a very particular chromosomal location. Now, consider the probability of having any retroviral insertions at all within an entire population's genome. Firstly, a retrovirus has to infect a particular cell out of the trillions of cells in a given organism's body. And not just any cell, but a sex (egg or sperm) cell. Secondly, that retrovirus must leave behind its genetic material. Now, that sex cell containing retroviral DNA must be part of fertilization - astronomically unlikely to happen at all. Next, that genetic material, which is transferred from the parent to daughter generation, must become fixed within the ENTIRE population/species in question. Note that neither "hotspots" or "chance" handwaving explanations begin to be capable of explaining what follows in light of this logic. If you find two people with these identical genetic markers at the same chromosomal locations, you can be sure that they're related via common descent, as it's far and away the most parsimonious explanation (versus random chance that not only all of the above actually happened, but happened in two separate organisms at a PRECISE chromsomal location). If you extend that logic across the species boundary, you'd expect two species which share a set of ERV's to be related by the very same logic. Guess what? We share a large number of these genetic markers with the other great apes (chimps, orangs, gorillas, etc). And not only do we share them (which is evidence in and of itself that we're related, as common descent is the only known viable way to account for two entire populations having identical sequences in the same chromosomal locations), we share them with a frequency proportionate to how close of a common ancestor we have with the other species. I.e. the more related we are to a given organism, the larger set of endogenous retroviral insertion points that we share. So: A) We share sets of genetic markers with other great apes and B) We can build a tree of relatedness using JUST this evidence, which overlays near-perfectly with the same trees built using morphologic and genetic characters  Source 1. Source 2. Source 3. 2) True tails Sometimes, people are born with tails. These tails can be "false tails," or extensions or extra material at the end of the spine due to any number of developmental problems of the fetus, or they can be TRUE tails. A "true" tail is one which contains muscle, nerves, and vertebrae. Note that creationist sources deny these even exist - but they do, and and they are documented within peer-reviewed literature:   Source 1. Source 2. Source 3. So, using the usual creationist argument of "no new information," we'd be forced to conclude that human ancestry contained the genetic material responsible for fully formed tails complete with muscle, nerve tissue and vertebrae but, for some confusing reason, were never meant to express it. We know what genes are responsible for tail formation in vertebrates - humans have it, though it is not normally expressed, and exists within our genome as a collection of pseudo-genes: Quote: In fact, the genes that control the development of tails in mice and other vertebrates have been identified (the Wnt-3a and Cdx1 genes; Greco et al. 1996; Prinos et al. 2001; Schubert et al. 2001; Shum et al. 1999; Takada et al. 1994). As predicted by common descent from the atavistic evidence, these tail genes have also been discovered in the human genome (Katoh 2002; Roelink et al. 1993). Source. So, given the reality of human tails both in expressed, peer-reviewed cases as well as within the literature in terms of our genome, I'd be curious to hear a possible creationist response to this one - God made us with fully functioning tails? For reference, all apes possess these pseudo-genes, as all apes (humans included) have common ancestry with the old world monkeys ~25 million years ago. The existence of true tails is an atavism - something predicted by common ancestry, and necessarily absent from special creation models (that is, unless you're willing to admit that humans and the other apes are the same created "kind"). 3) Objective, nested hierarchy of species Evolution works like a branching bush, NOT a straight line:  Within this context, every split in any particular lineage that results in a new lineage necessarily entails the new lineage inheriting the legacy/characters of the parent lineage. Over time, evolution then MUST build objective, nested hierarchies. A nested hierarchy is a "group within group." An objective nested hiearchy is one in which this grouping can hold no matter what collection of characters are used to build relatedness. So while you could feasibly build a nested hierarchy with cars, boats, or manufactured goods in general, NONE of these build objective nested hierarchies, as weighting different characters differently will build completely unrelated trees. Quote: The degree to which a given phylogeny displays a unique, well-supported, objective nested hierarchy can be rigorously quantified. Several different statistical tests have been developed for determining whether a phylogeny has a subjective or objective nested hierarchy, or whether a given nested hierarchy could have been generated by a chance process instead of a genealogical process (Swofford 1996, p. 504). These tests measure the degree of "cladistic hierarchical structure" (also known as the "phylogenetic signal") in a phylogeny, and phylogenies based upon true genealogical processes give high values of hierarchical structure, whereas subjective phylogenies that have only apparent hierarchical structure (like a phylogeny of cars, for example) give low values (Archie 1989; Faith and Cranston 1991; Farris 1989; Felsenstein 1985; Hillis 1991; Hillis and Huelsenbeck 1992; Huelsenbeck et al. 2001; Klassen et al. 1991). Source. The reality of objective, nested hiearchies of life is confirmed by the fact that all humans are apes, all apes are primates, all primates are placental mammals, all mammals are tetrapods, all tetrapods are vertebrates, all vertebrates are animals, and all animals are eukaryotes. It's the ONLY explanation we have why this "grouping within groupings" past and present actually exists - no other model demands it. Common design does NOT demand nested hierarchies. Can it accomodate it? Yes - but nothing about it PREDICTS the existence of grand, unified objective nested hierarchy of life, which is exactly what we find when analyzing real life phylogenies (again - this is statistically verifiable and verified): Quote: "the standard phylogenetic tree and nearly all less inclusive evolutionary phylogenies have statistically significant, high values of hierarchical structure (Baldauf et al. 2000; Brown et al. 2001; Hillis 1991; Hillis and Huelsenbeck 1992; Klassen et al. 1991)." Quote:  Figure 1.2.1. A plot of the CI values of cladograms versus the number of taxa in the cladograms. CI values are on the y-axis; taxa number are on the x-axis. The 95% confidence limits are shown in light turquoise. All points above and to the right of the turquoise region are statistically significant high CI values. Similarly, all points below and to the left of the turquoise region are statistically significant low values of CI. (reproduced from Klassen et al. 1991, Figure 6). Source. See also evidence on observed speciation/macroevolution below for a more in-depth explanation for how our observations of the organization of life are in accordance with the natural consequences of common descent through time. 4) Transitional fossils Within common descent, any two related groups of organisms in which a daughter group has ancestry in a parent group will have a number of transitions between the two lineages. The individual transitions lie like pieces of a puzzle between these two groups of organisms separated in time. So, while there's no way to guarantee that one of those pieces of the puzzle is directly ancestral to the daughter group, these "puzzle piece" organisms represent a mosaic of characteristics between two lineages. And this is the very definition of "transitional," because evolution is not a straight line, but a branching bush. So the theriapsids, a group of synapsid reptile-mammals are transitional between mammals and their synapsid ancestors. Examples of transitional characters include their gait, dentition, and jaw articulation. But "transitional" does not mean "has half a heart," is the DIRECT ancestor of a particular lineage, or some creationist strawman, it means exactly what is stated above, which is the actual prediction offered by evolution. Now, not all living things that have existed are fossilized - in fact, a fraction are, and we are lucky to have what we do. But of what we do have, we have a very, very large number of transitions, including devastating (for creationists) transitions between fish and amphibians, amphibians and reptiles, between synapsid reptiles and mammals, between diapsid reptiles and birds, and between ancestral apes and mankind:  Quote: Figure 1.4.4. Fossil hominid skulls. Some of the figures have been modified for ease of comparison (only left-right mirroring or removal of a jawbone). (Images © 2000 Smithsonian Institution.) Source. Note that these simply represent transitions within vertebrates, the group most commonly brought up by creationists themselves, but are by no means the only transitionals we have. We have a very large number of transitionals spanning across time in between many lineages of organisms, and the examples above are just a few of these. Also, here's a very short listing of web resources on transitional fossils creationists habitually deny exist: http://www.talkorigins.org/faqs/faq-transitional.html http://www.origins.tv/darwin/transitionals.htm http://home.entouch.net/dmd/transit.htm http://www.gcssepm.org/special/cuffey_04.htm http://asa.calvin.edu/ASA/resources/Miller.html http://www.actionbioscience.org/evolution/benton2.html http://www.gate.net/~rwms/EvoLimb.html http://www.christianforums.com/t43227-transitional-fossils.html http://www.agiweb.org/news/evolution.pdf 5) Observed speciation/macroevolution In Darwin's Origin of the Species, Darwin was attempting to explain how the diversity of life past and present appeared. The "origin" in question is where any given species comes from - not the beginning of life, which is covered in the field of abiogenesis. Within this context, Darwin speculated that natural forces, i.e. nature itself, could possibly explain the past and present diversity of life on this planet. He hypothesized that new daughter branches arise from existing parent branches, such that the daughter branches represent modified subets of the parent branch. Over time, then, life becomes a branching bush, NOT a straight line (as, previous to Darwin, had often been suggested - true Lamarckian evolution is precisely this, a linear ascent towards perfection, with mankind the pinnacle of creation). Darwin himself catalogued this pattern, which represents the very logic cladists would use many years later. So, Darwin's work was attempting to establish this pattern of divergence - given large amounts of geologic time, once you've established that this divergence DOES occur, you have established the very pattern that Darwin himself proposed. And guess what? We have WITNESSED this pattern of divergence occur in the field and laboratory - we have seen the very formation of new species in exactly the manner Darwin predicted SHOULD occur given the premise of evolution. So yes, we've seen one population split from a parent population such that the respective gene pools between the two populations are isolated (via behavior, sexual selection or geographic isolation) to the point where the parent and daughter populations no longer interbreed. At this point, we are FORCED to grant a new species name to the daughter lineage, which represents a new, biologically distinct taxon. That is the very definition of macroevolution, and exactly what Darwin predicted we'd find. The following is a list of over 100 peer reviewed examples of what is described above: http://www.christianforums.com/t155...speciation.html (Dr. Lucaspa's list of observed instances of speciation) http://www.talkorigins.org/faqs/faq-speciation.html (Talk.origins list #1) http://www.talkorigins.org/faqs/speciation.html (Talk.origins list #2) 6) The convergence of everything above Creationists normally try to obfuscate the reality of the weight of evidence for evolution by attacking particular lines of argument individually, a shotgun approach hoping that enough "holes" are made to cast doubt in the minds of would-be anti-evolutionists. Radiometric dating "must be wrong," so the reliability of dating these fossils must follow suit, of course. Nested hierarchies don't HAVE to be built via evolution (it's POSSIBLE God did it), so it CAN'T be evidence for evolution. Maybe the transitional forms were created that way, so they don't HAVE to be evidence for evolution. But what is rarely to never addressed by creationists is the overwhelming convergence of independent lines of evidence towards a single conclusion: that evolution has and is occurring. In short, why does the fossil record track with molecular studies (e.g. ERV-built phylogenies) track with radiometric and stratigraphic principles (in terms of dating and presenting a consistent chronology) track with a statistically verifiable, objective, hierarchial organization of species track with all the many other lines of evidence not listed here (e.g. biogeography, comparative anatomy/physiology etc). If each independent line of evidence is simply "wrong" or "faulty," why do so many independent lines of evidence point towards a common conclusion? That this is true is overwhelmingly confirmed by life scientists worldwide (of which some 99.85 - 99.90% accept the reality of everything I've said here). Creationists/IDists seem to spend every waking moment picking through the science of real scientists, looking for a damning quote, a single piece of evidence to hold up and say "ah-ha! this doesn't fit!" But these same creationists are at a total loss of explaining why all known evidence points to precisely the same conclusion. At that point, you hit the 'conspiracy' claims - that science is some atheistic/satanic conspiracy (I've heard the latter offered numerous times). If you feel like resorting to that, have fun wearing your tin foil hat, but you've let the last remaining embers of rationality die out.
 The best human beings start good new topics and vote on the better posts. |
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24HourForums.com > Supported Forums > Brian's Science & Nature Shack > 6 lines of evidence - evolution ain't going away | ||||||||||||||||||||||||||||||||||||||||
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