-
Posts
1588 -
Joined
-
Last visited
Content Type
Profiles
Forums
Events
Everything posted by lucaspa
-
What you are missing is that creationism/ID has already been falsified. The ideology is on the side of creationism/ID that refuses to admit that the theory has been falsified. It ignores the massive amounts of data and instead only tries to discredit the data supporting evolution. That assumes that there are valid criticisms of the paper. Experimentally, the approach is straighforward and simple. The assay for use of citrate is simple and all they are doing is thawing out previous generations to see where in those generations the ability to use citrate appeared. All in all, for the hypothesis the paper is stating and the conclusions the paper is reaching, the paper is very well written. I have a few minor quibbles with some of the figures. It is the soundness of the paper (and the study) that contributes to the ineffective and silly criticisms of it by creationists. There aren't any major valid criticisms. So Behe resorts to false witness about the nature of the use of citrate by E. coli in the wild. You should have read the rest of my post before you said this. As it turns out, the smoking gun that Behe is wrong is present in the paper! Oh yes. This is merely the latest salvo in the debate. It will continue. The argument, if you noticed, has already settled not on whether there is only determinism or contingency, but rather on how much contribution each makes. There is no such thing as "irreducibly complex" in the meaning that Behe uses. All"irreducibly complex" structures can be reached by one of the 4 modes of Darwinian evolution: http://www.cbs.dtu.dk/dave/JTB.html What standard would you use for "easy"? Evolution is constrained by history, so some structures or traits are not at all accessible to particular genomes. For instance, no tetrapod is going to be able to evolve a hexapodal structure. Once a trait is under 2 or more positive selection pressures, it is essentially unchangeable: G Wagner, Complexity matters. Science, 279, Number 5354 Issue of 20 February 1998, pp. 1158 - 1159 But that is the assumption made by Behe and other creationists. As you said, you don't know enough biology. This isn't true because the mutations appear sequentially. Also, more than one mutation will do the same basic job. As long as the first mutation confers any advantage (even if the advantage is not what the final product is going to be) then it will be fixed. This negates the idea of lower probability for the later mutations: they have the same probability of appearing as they always did. But that's what we are talking about, right? It's more difficult to track them down. But leaving out relevant facts is an outright lie. This is the smoking gun that made Behe's "wild guess" a lie. The reference is: "3. Pos, K.M., Dimroth, P., and Bott, M. 1998. The Escherichia coli citrate carrier CitT: a member of a novel eubacterial transporter family related to the 2-oxoglutarate/malate translocator from spinach chloroplasts. J. Bacteriol. 180:4160-4165." Here's the abstract. Look at what I bolded: "Under anoxic conditions in the presence of an oxidizable cosubstrate such as glucose or glycerol, Escherichia coli converts citrate to acetate and succinate. Two enzymes are specifically required for the fermentation of the tricarboxylic acid, i.e., a citrate uptake system and citrate lyase. Here we report that the open reading frame (designated citT) located at 13.90 min on the E. coli chromosome between rna and the citrate lyase genes encodes a citrate carrier. E. coli transformed with a plasmid expressing citT was capable of aerobic growth on citrate, which provides convincing evidence for a function of CitT as a citrate carrier. Transport studies with cell suspensions of the transformed strain indicated that CitT catalyzes a homologous exchange of citrate or a heterologous exchange against succinate, fumarate, or tartrate. Since succinate is the end product of citrate fermentation in E. coli, it is likely that CitT functions in vivo as a citrate/succinate antiporter. Analysis of the primary sequence showed that CitT (487 amino acids, 53.1 kDa) is a highly hydrophobic protein with 12 putative transmembrane helices. Sequence comparisons revealed that CitT is related to the 2-oxoglutarate/malate translocator (SODiT1 gene product) from spinach chloroplasts and five bacterial gene products, none of which has yet been functionally characterized. It is suggested that the E. coli CitT protein is a member of a novel family of eubacterial transporters involved in the transport of di- and tricarboxylic acids." They had to put CitT in a plasmid and transfect the E. coli before E. coli could use citrate in an aerobic environment. These E. coli were NOT in the wild and the ability to aerobically metabolize citrate comes from a human constructed plasmid. So there is nothing in this paper to contradict Lenski. As you said: " people who leave out facts or exaggerate are much more annoying to deal with than those who just outright lie " Behe limited his possibilities in order to attack the paper and try and say the paper did not show evolution. Like you said above: "people who leave out facts ... are much more annoying to deal with than those who just outright lie" Behe made it appear that his guess was the only valid guess.
-
But the medical help is "nature"! It's the present environment. Also, you forget that, while you might be preserving Jimmy's "sickness", you are also preserving other, beneficial traits. My favorite example is Stephen Hawking. Born with the genetic defect of Lou Gehrig's disease. Thanks to modern medicine, Hawking survived and had kids. So, the alleles for Lou Gehrig's disease were preserved, but also the alleles for Hawking's phenomenol intelligence were also preserved. Which is more beneficial in the long-term? Basically, your essay makes 2 basic errors about evolution: 1. That some traits are always "good" and others always "bad". In reality, traits are "good" or "bad" depending on the environment. Medical science is part of the environment. 2. You think you are smarter than natural selection. You're not. You want to pick the traits that should be preserved and the ones that should be discarded. But you can't see into the future. In eliminating Linda because you let her mother die of cancer when medical science could cure her, you might also be eliminating an allele that provides immunity to Ebola! You just don't know. Don't second guess natural selection with phrases like " The human race would have been stronger physically speaking" or we would be left with a much stronger, yet smaller population" You don't know the population would be "stronger" in the face of a future environment. No one does. You are only judging "stronger" on past environments. Environments that lack our technology. If we ever lose our technology, then natural selection will select for that environment. However, if you artificially select for that, you eliminate the variation that will be needed to cope with a future environment that is not like the past.
-
In this context it is unreasonable. Behe is using it to lower the epistemic value of the discovery. It's always good to go look at the primary article. Lenski isn't looking at demonstrating evolution in general but instead trying to delineate the relative contributions of contingency vs determinism. "This potentiating change increased the mutation rate to Cit+ but did not cause generalized hypermutability. Thus, the evolution of this phenotype was contingent on the particular history of that population. More generally, we suggest that historical contingency is especially important when it facilitates the evolution of key innovations that are not easily evolved by gradual, cumulative selection. " No, it doesn't. Because the "probability" is always calculated on the idea that the mutations must appear in the same generation. Thus, it is unlikely that all the mutations will appear in the same individual. But that isn't the case. The mutations can appear sequentially, with the first mutation having been fixed (present in all the individuals of the population) before the next mutation appears. Then the odds are much better because no matter what individual mutation #2 appears in, that individual will have mutation #1. Natural selection is a means to cut down odds. Now, back to the article. "Previous analyses of this experiment have shown numerous examples of parallel phenotypic and genetic evolution. All twelve populations underwent rapid improvement in fitness that decelerated over time (2, 3, 22, 23). All evolved higher maximum growth rates on glucose, shorter lag phases upon transfer into fresh medium, reduced peak population densities, and larger average cell sizes relative to their ancestor (22–26). " AHA! Something Behe failed to mention: E. coli in the wild that can transport citrate got them from plasmids: "Throughout the duration of the LTEE, there has existed an ecological opportunity in the form of an abundant, but unused, resource. DM25 medium contains not only glucose, but also citrate at a high concentration. The inability to use citrate as an energy source under oxic conditions has long been a defining characteristic of E. coli as a species (35, 36). Nevertheless, E. coli is not wholly indifferent to citrate. It uses a ferric dicitrate transport system for iron acquisition, although citrate does not enter the cell in this process (37, 38). It also has a complete tricarboxylic acid cycle, and can thus metabolize citrate internally during aerobic growth on other substrates (39). E. coli is able to ferment citrate under anoxic conditions if a cosubstrate is available for reducing power (40). The only known barrier to aerobic growth on citrate is its inability to transport citrate under oxic conditions (41–43). Indeed, atypical E. coli that grow aerobically on citrate (Cit+) have been isolated from agricultural and clinical settings, and were found to harbor plasmids, presumably acquired from other species, that encode citrate transporters (44, 45). " But these guys can't get their citrate from another species; there isn't any. Behe misled everyone by implying that E. coli by themselves could be Cit+. Not true. The ones in the wild need plasmids from other species. This is what Lenski tested: "The long-delayed and unique evolution of the Cit+ phenotype might indicate that it required some unusually rare mutation, such as a particular chromosomal inversion, that does not scale with typical mutation rates. Alternatively, the occurrence or phenotypic expression of the mutation that generated the Cit+ function might depend on one or more earlier mutations, such that its evolution was contingent on the particular history of that population. Contingent adaptations should tend to be complex and require multiple steps, some of which might not be beneficial, at least not uniquely so given other advantageous paths. Otherwise, cumulative selection would predictably favor the same steps, and the evolutionary path should be repeatable (18). Contingent adaptations should thus display two characteristics. First, independent origins should be rare, because the same historical sequences would rarely recur (19). Second, significant time-lags should occur between the presentation of ecological opportunities or challenges and the evolution of those traits that confer adaptation to those circumstances (46). " And Lenski concludes that he is looking at a contingent adaptation: "These analyses compel us to reject the hypothesis that a rare mutation could have produced a Cit+ variant with equal probability at any point in the LTEE. Some unusually rare mutation might be involved, but its rarity does not provide a sufficient explanation for the unique and exceptionally slow evolution of this new function during the LTEE. Our results instead support the hypothesis of historical contingency, in which a genetic background arose that had an increased potential to evolve the Cit+ phenotype. " "The evolution of the new Cit+ function represents a key innovation that involves multiple steps, and it provides an explicit demonstration of the importance of historical contingency in evolution. It also transcends the phenotypic boundaries of a diverse and well studied species, and led to an ecological transition from a single population to a two-member community. Our future research on this fascinating case of evolution in action will revolve around four themes: genetics, physiology, ecology, and speciation. What is the genetic basis of this evolutionary innovation? The emergence of the Cit+ phenotype in population Ara-3 indicates at least two important genetic events: the origin of the function in its weak form, and its subsequent refinement for efficient use of citrate. " The bolded part is very important. This is the first instance of E. coli itself being able to use citrate in the medium as a food source. All other cases say E. coli got the ability from a plasmid from another species. "A more likely possibility, in our view, is that an existing transporter has been coopted for citrate transport under oxic conditions. This transporter may previously have transported citrate under anoxic conditions (43) or, alternatively, it may have transported another substrate in the presence of oxygen. The evolved changes might involve gene regulation, protein structure, or both (61). "
-
As I read the data: http://www.nature.org/wherewework/northamerica/states/southdakota/news/news2446.html http://boldventure.info/dna.html it appears that, altho artificial insemination is not used, artificial breeding conditions are used. IOW, a bison bull is presented only with cattle females in heat. Part of reproductive isolation is mate choice, and mate choice is not permitted. For the wild herds, initial DNA testing does not show hybrids: "Tail hairs from 100 bison at Ordway Prairie were collected in the fall of 2006 and evaluated for cattle interbreeding in 2007. So far the results show only one animal has cattle genetics," That's not much. Also, it appears that not all hybrids are fertile. The second website takes pains to list each and every individual animal that is. That makes me think that this is unusual. So I question the premise that bison and cattle are completely interfertile. Probably differs from species to species. Although it may be fairly constant in terms of generations. May. Researchers are just starting to look at the molecular basis of speciation. The gene involved in hybrid sterility has been identified at least in Drosophila and mammals have an homologous gene: 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. The difference was 10-15 amino acids between sibling species.
-
That wasn't the question. That's how you get them: buy them from ATCC. The level 2 biosafety cabinet is not so much to protect you from the cancer cells as to protect them from all the microbes around. If Octaviasplay wears exam gloves, a lab coat, and does not drink the culture media then he/she will be OK. Now, without training in sterile technique and a level 2 biosafety cabinet, the cells won't be OK for long. Octaviasplay is going to find that he/she is working with bacterial or fungal cultures instead of cancer cells.
-
Not all chest pain is associated with heart related problems. For instance, you can get muscle cramping in the chest muscles. However, the symptoms described in the OP, particularly pain or numbness in the left arm, are typical of a myocardial infarction. Antimatter's post could be angina, muscle cramping, or perhaps a medialstinum tumor. He/she should go to a doctor to check it out. The deal is that, with chest pain, it is better to be safe than sorry. If you get severe chest pain, if it is a heart attack and you ignore it, then you are really, really screwed. If you call the paramedics and it isn't a heart attack, there is a bill to pay but basically no harm done.
-
For a video on how to give a good talk, this is a terrible talk! It doesn't tell you much about what he is really doing.
-
Why Do Bacteria Stay Bacteria in Evolution?
lucaspa replied to jimmydasaint's topic in Evolution, Morphology and Exobiology
Mutations provide the raw material for selection. What gets selected depends on the environment the population is facing. Bacteria in hot springs do have alleles (forms of genes) that are different from bacteria living elsewhere. But that doesn't mean all those bacteria have to give up those genes. The other alleles do better in cooler environments. Remember, every mutation has a cost as well as a benefit. It depends on the environment if the benefit outweighs the cost. When the cost is higher than the benefit, the older form does better. Most speciation comes about by splitting a population in 2. The "old" population is well-adapted to its niche. It doesn't change. The "new" population faces a different environment with different selection pressures. Those selection presssures dictate change. Read the thread "Three forms of natural selection". You are thinking of natural selection only in terms of directional selection. You are forgetting purifying selection. Long ago one species of bacteria evolved to first a eukaryotic organism. Then one species of eukayote evolved to a multicellular oraganism. That species then kept splitting to give us all the multicellular species we see today. Meanwhile, the niches occupied by bacteria and single celled eukaryotes (like algae or amoeba) were still good ways to earn a living. Natural selection kept those species adapted to those niches -- including being single celled. As someone pointed out, tho, many bacterial species have multiple interactions with other bacteria and often act almost like a multicellular organism. It's an intermediate form on the way to multicellularity. However, that intermediate is still a good way to earn a living. It's still evolution -- descent with modification. Mitochondria and chloroplasts are much modified from their bacterial ancestors. One modification is that many of their genes are either in the nucleus or the mitochondria and chloroplasts use the proteins from genes that were originally in the nucleus. As I said -- cost/benefit. The cost of making 2 copies of the genes outweighed the benefit, so modern eukaryotic cells only make one copy that is used in both the cytoplasm and the mitochondria. BTW, there is a thread on "Endosymbiosis" that talks about the fact that mitochondria and chloroplasts are the result of bacteria becoming parasites, then symbionts, and then endosymbionts. -
Considering that the original researchers haven't found the change that allowed the E. coli to metabolize citrate, how does Behe know it is an overexpression of the citrate transport protein? AH! He doesn't! He says that a known variant of E. coli that can use citrate has an overexpression of citrate permease, therefore he makes the leap (without data) that this is the case here. Once again we see the pattern with creationism/ID: no experiments testing predictions of their own, just attempts to explain away data gathered by experiments testing evolution. What Behe forgets is that natural selection is cumulative. He is still trying to say that you need several simultaneous mutations in the same individual, forgetting that you can have sequential slightly beneficial mutations such that each becomes fixed in the population before the next appears. Also, Behe is forgetting that bacteria have the lowest mutation rate of all organisms. It's no wonder it took so many generations. It's about 0.00001 compared to 20 for humans.
-
Haltose is correct in that the categories are not strict. This is what Futuyma says in Evolutionary Biology: "Subspecies: A taxonomic term for populations of a species that are distinguishable by one or more characteristics, and are given a subspecific name (e.g. the spuspecies of the rat snake Elaphe obsoleta; se Figure 21 in Chapter 9). In zoology, subpecies have different (allopatric or parapatric) geographical distributions, so are equivalent to "geographic races;" in botany, they may be sympatric forms. No criteria specify how different populations should be to warrent designation as subspecies, so some systematists have argued that the practice of naming subspecies should be abandoned." pg 450 "Semispecies: Usually, one of two or more parapatric, genetically differentiated groups of populations that are thought to be partially, but not fully, reproductively isolated; nearly, but not quite, different species."
-
American Type Culture Collection. You can find them on the web. They are a national repository for cancer cell lines.
-
Which is why the latter is so important. If a species does not interbreed, eventually the genetic distance will get to the point that they can't. By genetic drift if nothing else. However, the point protist was making was that, in considering biological species, not interbreeding makes separate gene pools long before the genetic changes accumulate to "can't interbreed" (infertility). So, altho lions and tigers "can" interbreed in the sense that you can do artificial insemination to make ligers, lions and tigers are, in biological fact, separate species because they simply don't interbreed on their own. It is the "don't interbreed" that is critical biologically.
-
I can't get to other pictures at the site to compare his other photos. In fact, can't even get to Amud1 from his index site! http://www.modernhumanorigins.net/hominids.html OK, found the problem. The site owner uses .com in the links but the site is now .net. So if I go to the links and then change .com to .net I can get the pictures. Thanks, CDarwin, this is a very useful site. You think there's a chin? I don't see a projecting chin like H. sapiens. You still have a recessed chin. Go to http://www.modernhumanorigins.net/shanidar4.html and you get the same chin. Compare to http://www.modernhumanorigins.net/kowswamp1.html to see how the sapiens chin bone comes slightly in front of the teeth in the lower jaw.
-
The genetic data is very clear that sapiens and neandertals are 2 separate species and there was no interbreeding to the point that Europeans have neandertal genes. That's not to suggest that an occasional neandertal Romeo and sapiens Juliet got together voluntarily or that an occasional sapiens male did not rape a neandertal female or vice versa. But genes old enough to belong to neandertals are simply NOT in human populations. The fossil you are referring to was disputed as to what the characteristics really meant: 5. Ian Tattersall*, and Jeffrey H. Schwartz, Commentary Hominids and hybrids: the place of Neanderthals in human evolution PNAS 96, Issue 13, 7117-7119, June 22, 1999 http://www.pnas.org/cgi/content/full/96/13/7117 But that has been overtaken by the genetic data. The Multiregional Hypothesis (championed mostly by Milford), where sapiens arose by interbreeding of various pre-sapiens species in Africa, Europe, and Asia, has been disproved. 9. A Gibbons, Modern men trace ancestry to African migrants. Science 292:1051-1052, May 11, 2001. Y chromosome of EVERY person in the study could be traced to forefathers who lived in Africa 35,000 to 89,000 years ago. "one self-described 'dedicated multiregionalist,' Vince Sarich of the University of California, Berkeley, admitted: 'I have undergone a conversion -- a sort of epiphany. There are no old Y chromosomes lineages. There are no old mtDNA lineages. Period. It was a total replacement.' " In another study, Peter Underhill and colleagues analyzed 218 markers in 1062 men from 21 populations.Primary paper is Y Ke, B Su, D Lu, L Chen, H Li, C Qi, S Marzuki, R Deka, P Underhill, C Xiao, M Shriver, J Lell, D Wallace, RS Wells, M Selestad, P Oefner, D Zhu, W Huang, R Chakraborty, Z Chen, L Jin, African Origin of modern humans in east Asia: a tale of 12,000 Y chromosomes. Science 292: 1151-1153, May 11, 2001. Can you name these skulls? The data I have seen from Mt. Shkul is that neandertals and sapiens co-habited the same area for 60,000 years and there are no hybrids. There are some older skulls showing the transition of H. erectus to neandertals: Stenheim and Swanscombe, 250 Kya: called H. heidelbergensis but have characteristics of both erectus and neandertalis. Large brows and small cranium ( ~1200cc) but otherwise looks like neandertalis Petroloma skull (complete): brow ridges and low forehead like erectus but not quite as primitive but not as derived as sapiens or neandertalis. Back of head resembles sapiens. 250 Kya Ehrendorf in Germany and Saccopestore in Italy: mixture erectus and early neandertals, classed as archaic H. sapiens or H. heidelbergensis.
-
The point was that bad designs are not a scientific problem. Bad designs do not argue against the scientific validity of ID. The "bad" designs can still be artifacts manufactured by an intelligent entity. After all, the rack and thumbscrews are manufactured artifacts by sadistic humans. There are ample examples of stupid designs manufactured by humans. Think of the Pinto and its exploding gas tank as just one example. Or the Soviets putting a critical oil line right under the big red star on the side of their helicopters so that the mujahaddin had a nice aiming point to hit it. The "bad design" argument only works against ID if you have the theology that deity is "good", "more intelligent than humans", and "kind". If the deity is not too bright and sadistic, then the "bad" designs can still be manufactured by the ID. So the bad design argument is not a scientfic argument but a theological one. The bad design arguments says that ID has theology that is not consistent with Judeo-Christianity. You can't limit "they choose to believe what they are told" to only religious faith. If you do, you are using the fallacy of Special Pleading. What you are doing, SkepticLance, is making an airtight argument to have creationism/ID included in science class! I know you are trying to decrease the status of religious also say that kids will believe what they are told in science class also! Therefore, in order not to "indoctrinate" children, we must tell them about alternative ideas, not just teach them evolution! I think the price we have to pay for you to keep your mythology of why people believe things is just too great. Let's take your native people example and see, how with a few changes, it can apply to science: Ever hear of Thomas Kuhn? What you have just described is "normative" science and scientific revolutions. Kuhn says that, most of the time, scientists work within paradigms and there is no, or little, change. Then comes a situation where a new paradigm is encountered. There is a period of conflict and the new paradigm is accepted, or rejected, because the power of the people to argue for it is so clear cut or there is a powerful emotional appeal. The winners then establish the paradigm, teach only that paradigm, fund only that paradigm, scientists simply follow the paradigm they are taught. Do you really think science works like that? I don't. I think theories are evaluated on evidence. Now, if people evaluate ideas based on evidence in science, how, without invoking Special Pleading, can we argue that people do not evaluate ideas outside science? Including religious faith. Yes, the white people were more powerful, and that might be one piece of evidence the natives used to reevaluate their faith. Many religions equate the power (and reality) of deity with the fortunes of believers. If the believers do not do well or people with other theories of deity do better, then that becomes evidence that the other theory is better and more accurate. Because the evidence didn't change. Look at geocentrism. Scientists for well over 1800 years accepted the theory that the earth was the center of the solar system and that the sun and planets orbited the earth. Then in the period 1543-1633 (4 generations) it all changed. Most of the change occurred within the period 1590-1609 (when Kepler published his planetary laws of motion), shorter than a single generation. A rapid change due to new data. You haven't shown that faith is the opposite of skepticism. Instead, what you showed was that skepticism is an integral part of faith. What you showed was that some religious leaders fight skepticism. So, religious faith is skeptical. As you say, it is skepticism which leads to the repression. Thank you for proving your point wrong. If you look into science, you can also find many examples where the prominent leaders in science have tried to repress the new ideas. Look at Owen's attacks on Darwin and evolution as just one example. Or better yet, look at the scientific establishment's (including Darwin) attack on Vestiges of Creation. Repressing the new idea of evolution. What happens in science is that the leaders don't have the political power to repress the ideas to the extent of the Inquisition or Taliban. It's not that the desire was lacking; the power was lacking. Fortunately. Finally, consider that your view is counter to evolution. Natural selection is never going to work at getting people to believe things that are contrary to the evidence. Such an attitude is anti-survival. The theory is really the grandmother theory. In hunter-gatherer societies, it is the grandmothers that help care for the infants, not the grandfathes. It explains why females live longer than males. Longer lifespan is selected for in females. Males get the longer lifespan as a benefit, not as directly selected. http://www.hno.harvard.edu/gazette/1998/10.01/WhyWomenLiveLon.html I can't find any source documenting your claim that female apes live a lot longer than male apes. Perhaps you can share your source. However, I do find several cites indicating that ape lifespan is basically the same as human. Which does call into question the grandparent hypothesis: http://michellegilders.hosting4less.com/michellegilders/greatapelife.html http://www.enchantedlearning.com/subjects/apes/chimp/ Sorry, but for our evolutionary history, grandparenthood came in the 30s. Think about it. Humans can have children starting at 15 or so. That means that grandparents are going to be in their 30s. And, for most of history, 35 was indeed the general lifespan with a few lucky individuals living into their 60s. If you look, most of the degenerative diseases -- athlerosclerosis, cardiac infarcts, arthritis, tendonitis, osteoporosis, cancer -- happen in the 50s to 60s. When natural selection is done with us because the grandmothers have already taken care of the grandkids.
-
As you noted, birds and animals spread seeds, they do not plant them. Birds and animals usually pass the seeds thru their digestive tracts and they fall out with the feces. Agriculture is very different. It is deliberately placing seeds where you want them, in conditions that are particularly favorable to their sprouting and growing. And then making sure the plants you want are not crowded out by plants you don't want. It's still a problem, because, from the plant's pov, all that is needed is that a few plants grow to produce more seeds. But agriculture requires that the vast majority be the plants that you want. Unless the plant is a transplant to a new ecology (like kudzu), you don't have that. As you said, natural selection designed ants to do agriculture. But natural selection did not design apes to do so. Chimps and humans have to do agriculture intellectually, and it appears that natural selection did not design chimp brains for the required abstract thought and foreplanning necessary.
-
Let's start off with remembering what "dark matter" is. It is a catch-all term for any matter that does not emit light on its own. Earth is "dark matter". So are all the non-sun bits of matter (planets, asteroids, comets, and any odd rock) in the solar system. The hydrogen between the stars is also "dark matter". The problem is that estimates of the common types of "dark matter" are still far less than the amount of matter needed to account for the motion of stars in galaxies we can observe (such as Andromeda). http://imagine.gsfc.nasa.gov/docs/science/know_l1/dark_matter.html Matter condensed out of energy as the universe cooled. It originally condensed as hydrogen and helium. However, there are other particles out there -- such as neutrinos. One hypothesis for the unknown dark matter is neutrinos. Neutrinos may have mass. Not much, but there are a lot of neutrinos. "Dark energy" is a term to give some kind of "name" to the observation that the expansion of the universe is accelerating. That is, the rate of expansion is getting faster and faster. Something is pushing spacetime to expand. We have no idea what that is, but needed a short label for it because saying "whatever it is that is pushing spacetime to expand" is inconvenient every time anyone wants to refer to it. "Dark energy" is just much shorter. Big Bang does not depend on their being dark energy. Big Bang was just fine when we thought that there was enough matter to have enough gravity to stop the expansion imparted by the Big Bang. Singularities are not an error of General Relativity. Rather, they are a prediction, or expected result, of General Relativity. Enough mass in a small enough spacetime can warp spacetime to such an extent that gravity is so strong that not even light can escape. So singularities -- black holes -- are actually a confirmation of General Relativity. What we have are two great theories that describe the universe on diffent levels: General Relativity and Quantum Mechanics. GR describes gravity. QM tends to describe everything else, and everything else occurs in quanta. However, gravity apparently is continuous and does not occur in discrete units (quanta). String or M Theory is an attempt to find a theory of quantum gravity and unite GR and QM. 1. http://superstringtheory.com/ http://superstringtheory.com/basics/basic3a.html 2. MJ Duff, The theory formerly known as strings. Scientific American, 278: 64-71, 1998 (Feb.). 3. AN Arkani-Hamed, S Dimopoulos, G Dvali, The universe's unseen dimensions. Scientific American 283: 62-69, Aug 2000. String Theory posits many dimensions, all but the 4 we see around us are "rolled up" and indectable to our naked senses. However, those rolled up dimensions are supposed to be detected if we can probe smaller scales. The problem right now is that we have instruments that are at the large end of the scales at which the rolled up dimensions can be detected. But they aren't: 5. Kaku M, Testing string theory. Discover August 2005 http://www.discover.com/issues/aug-05/cover/ So far ST has been saved by positing that the dimensions are smaller than thought and still lie below the detection threshold. But, as instruments get more sensitive, that ad hoc hypothesis won't last forever. ST needs to come up with some observational consequences soon or be falsified. I have also seen (mostly advertised by Smolin) that some physicists have done some math and there are thousands of variations within ST that could all be consistent with our observed universe. That doesn't sit well within science, where the idea is that only a single theory will describe reality. If you've got thousands of solutions, all of which are equally compatible with observation, then the feeling is that the theory is fatally flawed. This doesn't have to tie in with Big Bang. Big Bang is independent of what dark matter is or whether there is dark energy and what it is. Sorry, but "no". What caused the Big Bang is separate from a GUT. The GUT describes the interrelation of matter/energy/spacetime within the universe. It is not going to tell you how to get a universe to begin with -- and getting the universe to begin with is the cause of BB. Now, we may get lucky and the GUT might also tell us the cause of the BB. But it doesn't have to. BB is simply the idea that the universe started off in an infinitely small, infinitely hot point of spacetime and has been expanding ever since. Included within the "hot Big Bang" theory is how the matter of the universe got to be so evenly distributed on large scales -- inflation. The cause of the expansion, the origin of that point of spacetime, the amount of "light" and "dark" matter and the composition of each, and GUT are not part of BB. Foodchain, theories have limits and boundaries. NO theory describes everything. Even the so-called "Theory of Everything" really only unites GR and QM. That still doesn't explain abiogenesis, the origin of species, or any number of other things. IOW, the ToE will not explain everything. There are still going to be separate theories that explain different things within the universe.
-
I'm glad iNow gave you the website. If you can't get the full article, e-mail me and I'll send you the PDF. Untrue. Big Bang was proposed and supported by data long before dark matter and dark energy were found. Dark matter was proposed because the motion of stars within galaxies can only be explained by masses of invisible matter lying outside the orbits of the stars (peripheries of the galaxies). It was originally thought that the discovery of the acceleration of the expansion (dark energy) would refute the Big Bang! However, it has now een shown that this is not the case: 12. MA Buchner and DN Spergel. Scientific American, 280: 62-71, Jan. 1999. Discusses changes in inflationary theory to account for new observations. 4. J Glanz, Microwave hump reveals flat universe. Science 283: 21, Jan 1, 1999. Data on microwave background radiation indicates that universe is flat. Means there must be the cosmological constant. And inflation theory survives. And no, galaxies are not orbiting anything. The motion of various galaxies is not what we would see if they were orbiting anything. As mooeypoo noted, discussion with you will go better if you read a bit of the science and the history. If you had, you would not have made the glaring error that dark matter and dark energy are required for BB.
-
The data is what it is. Here are some articles. You shoud be able to find all the journals at your public library. 5. A Watson, Clusters point to a never-ending universe. Science, 278: 1402, 21 Nov. 1997. Discusses paper that will appear in Astronomy and Astrophysics about the clusters that bend light from distant objects. The model predicts the number of such clusters we should see. With 33% of the critical mass the model predicts 2500 clusters. We see 2300-2700. Up the mass to the critical value and the predicted number drops to 25. 7. J Glanz, Exploding stars point to a universal repulsive force. Science 279:651-652, 30 Jan. 1998. New data indicates the cosmological constant is back. 7a. J Glanz, No backing off from the accelerating universe. Science 282: 1249-1250, Nov. 13, 1998. As the title says, 2 independent and competing groups continue to get data that agrees. 8. G Tarke and S.P. Swordy, Cosmic Antimatter. Scientific American, 278(4): 36-41, April 1998. 10. CJ Hogan, RP Kirshner, and NB Suntzeff, Surveying space-time with supernovae. Scientific American, 280: 46-51, Jan. 1999. Studies indicate that the rate of expansion of the universe is accelerating. 11. LM Krauss, Cosmological antigravity. Scientific American, 280: 52-61, Jan. 1999. discusses cosmological constant to explain accelerating expansion. 4. J Glanz, Microwave hump reveals flat universe. Science 283: 21, Jan 1, 1999. Data on microwave background radiation indicates that universe is flat. Means there must be the cosmological constant. And inflation theory survives. 15. SJ Goldstein, Jr The cosmological constant. [letter] Science 283: 794, Feb. 5, 1999. Attempted critique of using supernovae to measure distance. Answered by J Glanz in a Response. 15a. K Wright, Very dark energy. Discover 22: 70-76, March 2001. Readable lay article 17. LM Krauss and GD Starkman, The fate of life in the universe. Scientific American 281: 58-67, Nov. 1999. Speculation of fate of the universe based on continued expansion.about new discoveries in cosmology, including increasing rate of expansion.
-
The articles in Science you can find in your local public library, because they all carry Science. Or, if you really like science, I suggest you become a member of the American Association for the Advancement of Science -- you get a subscription to Science as part of your membership. Otherwise, like iNow said, you will probably need to spend a Saturday in a university or college library and do some photocopying. An alternative is to Google using the title of the paper in quotes. Many scientists now are putting up PDFs of their papers on their websites. Species are NOT a label. Species are the only biological reality. Genera and higher taxa are labels applied by humans for groupings of species. As I've stated before, there can be no precise definition of species because evolution happens. Since populations transform from one species to another gradually over dozens, hundreds, or thousands of generations, you will always be able to find populations in the midst of the transformation. The biological species concept is: "Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups." (Mahr 1942) Reproductive isolation is also a gradual process. It doesn't mean non-fertile, but means that individuals do not interbreed, even if they could produce fertile offspring. As you noted, coyotes and wolves simply don't view each other as mates. Below are isolating mechanisms: "Classification of Isolating Mechanisms 1. Premating or prezygotic mechanisms: Mechanisms that prevent interspecific matings. (a) Potential mates are prevented from meeting (seasonal and habitat isolation) (b) Behavioral incompatibilities prevent mating (ethological isolation) © Copulation attempted but no transfer of sperm takes place (mechanical isolation) 2. Postmating or postzygotic mechanisms: Mechanisms that reduce full success of interspecific crosses (a) Sperm transfer takes place but egg not fertilized (gametic incompatibility) (b) Egg fertilized but zygote dies (zygotic mortality) © Zygote develops into an F1 hybrid of reduced viability (hybrid viability) (d) F1 hybrid is fully viable but partially or completely sterile, or produces deficient F2 (hybrid sterility)" Ernst Mayr, What Evolution Is pg 171 Will a wolf and dog voluntarily breed in the wild? If not, then we can define wolves and dogs as different species. It appears that such interbreeding occasionally takes place, but not very often. Here is an article: http://archonline.bio.bg.ac.yu/VOL58/SVESKA%204/06.pdf
-
Evolution of winged insects
lucaspa replied to helloween's topic in Evolution, Morphology and Exobiology
It appears to be complicated. Some people are hypothesizing that crustaceans and hexopods (of which insects are a part) form a clade called "pancrustacea". A news summary in Science is here: http://www.sciencemag.org/cgi/content/full/314/5807/1883 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1634985 The most recent comprehensive book about insects and their evolution is here: http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=0521821495 -
Evolution of winged insects
lucaspa replied to helloween's topic in Evolution, Morphology and Exobiology
http://www.bio.psu.edu/People/Faculty/Marden/project2.html http://www.kgs.ku.edu/Extension/fossils/insect.html Insect wings seem to be an example of exaptation: evolving for one function and then suddenly gaining another function. In the case of insect wings, they are modified gills and appear to have been originally used as heat exchangers by land dwelling, but wingless insects. A study by JG Kingsolver and MAR Koehl published the first hard data to support a shift from thermoregulation to flight as a scenario for the evolution of wings. The article is "Aerodynamics, thermoregulation, and the evolution of insect wings: differential scaling and evolutionary change", Evolution, 1985. Using models the authors showed that the modified gills were better as heat exchangers as they got larger. The point where the modified gills were optimal as heat exchangers turned out to be the minimal point where the modified gills could act aerodynamically as wings. You can find it discussed by SJ Gould in "Not necessarily a wing" in Bully for Brontosaurus, pg. 139-151, 1991. and in an updated review by Kingsolver and Koehl here: ftp://128.32.118.46/pub/koehl/Kingsolver_Koehl_1994.pdf -
Doesn't matter. The data is clear that the expansion -- by whatever cause -- is accelerating. The expansion is such that the gravity of the universe will never be able to slow it down and bring all the matter back together to a Big Crunch. This is a one way trip. It's already too late for that. Not enough matter to make enough gravity. If dark energy stopped today, the universe would continue to expand forever. Ekpyrotic is different. You have a 5 D universe in which 2 4D branes sit. One of the branes sheds a brane that floats toward the other one. When those 2 branes collide the 4 D universe is wiped out but a new 4 D universe comes into being. Not exactly "cyclic". The acceleration of expansion is interpreted as moving toward that new brane. Of course, ekpyrotic depends on M Theory, and M Theory is in trouble.
-
That's a big "if". A million years ago the morphology is so different that the species is H. erectus. Let's drop back 50,000 years when there were at least morphological H. sapiens. Right. It means that we are in the middle of an transition from one species to another (unlikely since our population is so large, but we can do your hypothetical). In all likelihood, the individual from the future would be assigned the new species name within the genus Homo. Call it H. futurus. Our rights are set for H. sapiens. We would have to choose to extend those rights to H. futurus. And, conversely, if you were transported to that society, it would have to choose to extend their rights to you. We are not required to do the extending. This gets back to what I kept alluding to in terms of AI and possible chimeras and ETs: sapience. I would argue that we would (and should) decide to include sapient intelligences as part of "people". But you are still in the genus Homo and looking at a chronospecies. You haven't addressed the other implications of your statement. After all, you just say "species membership" as any species. Does that mean it is morally wrong to kill the fire ants in my lawn? If species membership is not morally relevant, isn't that murder? Or how about the predator/prey relationship? Is the predator committing murder by eating the prey? If you say "yes", then you condemn the predator to starvation. Not completely. There are some rights that a mentally retarded H. sapiens does not have. Mental status does count in determining person status. After all, Terry Schiavo lost her status as a "person" because she lost her mental status, didn't she? No brain = OK to kill. No longer a person. Similarly, by the reckoning of many people's ethics, a 3 month or less H. sapiens fetus is not a "person" either, is it? It doesn't have mental ability. In terms of other species? Yes. All or nothing. In terms of members of H. sapies, it's obvious that we do have a gradation of "personhood". Children do not have all the rights of adults. During adolescence we gradually provide part of the freedoms we assign to adults -- to drive, to drink, etc. You answered the second question yourself later in your post: "basing the ethical consideration ... on the relevant properties of the average healthy member of the species in question." As it happens, I also suggest the comparison be to an average adult of the species. From what I have seen, chimps and other apes have average mental abilities comparable to an average 6 year old H. sapiens child. How can there be a gradient when you say "all creatures being on an equal footing morally? If you make a "gradient", then some are lower and some higher on the gradient! Sorry, Yourdad, you can't say equal and then say "gradient". Sure it is. A shark has no morally relevant property against killing a human. A shark's morality in this is due to belonging to its species. Similarly, the Black Plague bacilli's morality of making people ill and killing them is based on its species membership. This is what this species of bacillis does! You keep bypassing, Yourdad, that humans simply can't live without killing members of other species. We are an animal! We have to at least kill plants for food. So, if species membership is not a morally relevant property, then you are being immoral every time you eat! Your only "moral" choice is to starve to death. ??? Nepotism is giving favors to your relatives. But let's examine your statement. You look at a human and a corn plant. You need to eat to survive. Isn't membership in the species alone that gives you the ethical consideration that it is OK to eat the corn plant but not OK to eat the human? If not, what other consideration is there? ??? Please provide an example to explain what you are thinkig of. As far as I can see from what you are saying, if your decision to eat affects a large number of corn plants (individuals of a species), then it is OK to kill them. Basically, Yourdad, you are providing a great justification for genocide! Or speciescide. Say your actions are going to destroy most of a species or several species -- as in cutting down the Amazon rainforest -- then you are saying it is OK to use species membership as a means of deciding if it is moral! Since they are not of your species, then it becomes moral. I'm sure you are going to be outraged and yell "strawman" (without explaining how it is a strawman), but what I said follows logically from what you said. I don't think you are thinking thru the consequences of what you are saying before you say it. Or perhaps you are parroting someone else and haven't thought thru what they said. Why isn't a preying mantis a person? You keep saying the species membership is irrelevant: "I maintain that species membership is not morally relevant" Preying mantis has a brain. What qualifies as "morally relevant properties"? I ask this especially since you keep reiterating "Species membership is not a morally relevant property". An inevitable conclusion from this is that all members of all species have the same morally relevant properties. 1. I did not say "ditch science". I said "wave bye-bye to science. Science is not a system of ethics." You also should have read to the end of my comment before you posted. I said at the end "Just recognize, Ecoli, that you might try to bring good science to a discussion, but that doesn't make the discussion "scientific". " 2. Science is not, and does not deal with, all of reality. It is a small subset of reality. Most of human existence takes place outside of science. As SJ Gould noted: "Science is a discipline, and disciplines are exacting. All maintain rules of conduct and self-policing. All gain strength, respect, and acceptance by working honorably within their bounds and knowing when transgression upon other realms counts as hubris or folly. Science, as a discipline, tries to understand the factual state of nature and to explain and coordinate these data into general theories. Science teaches us many wonderful and disturbing things - facts that need weighing when we try to develop standards of conduct and ponder the great questions of morals and aesthetics. But science cannot answer these questions alone and cannot dictate social policy. ... We live with poets and politicians, preachers and philosophers. All have their ways of knowing, and all are valid in their proper domains. The world is too complex and interesting for one way to hold all the answers. " Stephen Jay Gould in the essay "William Jennings Bryan's last campaign" in Bully for Brontosaurus, 1991, pp. 429-430.
-
Ah, but note that qualifier "if". That qualifier is not there in real life, is it? Yourdad did not have the qualifier. He said "species membership doesn't matter". He said nothing about intelligence, sentience, etc. mattering either. You have a different set of criteria to what matters. So, let's deal with this in the real world where fire ants do not have the capabilities you listed after your "if". Do you still agree with Yourdad then? Good! The premise of the film and your post is what we have talked about before in several versions: traits are only "good" or "bad" in different environments. There are very few absolutely good or bad traits. And, even if a person has one, there are lots of other alleles that are beneficial to the population if the person could just pass them on. Back to the prime example of Stephen Hawking. He suffers from Lou Gehrig's disease, which is genetic. Drugs kept him alive long enough for him to have kids. So they have the alleles for the disease. BUT, they also have the alleles for Hawking's brilliant mind! Do you really want to lose the alleles for the mind because you have some idea that the disease is "absolutely" bad and must be eliminated? Basically, natural selection is much smarter than we are. Part of the environment is the technology to let people live that, in an environment without the technology, would otherwise die. Just let natural selection work so that we can keep as much genetic variability in the population as we can. Sorry, but the data shows otherwise. If you have ANY positive s (selection coefficient), no matter how small, the mathematics of population genetics guarantees that eventually that allele will become fixed (100% frequency in the population).