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Member (Idle past 6475 days) Posts: 3085 From: Munich, Germany Joined: |
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Author | Topic: Overkill, Overchill, Overill? Megafaunal extinction causes | |||||||||||||||||||||||
Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
quote: As I just stated, you can have 12 million people (plenty to kill off mammoth populations), and still have them be scattered bands. What is so difficult about this for you to understand? Are you expecting some sort of herd of 10 million mammoths all in one location? If so, that's preposterous, there never would be near enough food for them. The 25-60 million (depending on which estimate you use) buffalo in the early 1800s roamed through a good portion of the great plains in search of food. Were the indians all in one location when hunting buffalo? Did they leave these massive buffalo kill sites? What you're expecting to find goes completely against all evidence for human hunting in history.
quote: 1) I never once have criticized overill for a lack of evidence. Quite to the contrary, I wouldn't expect to find very much evidence for it even if it did happen. 2) You're not allowed to ask for evidence for something that I'm not advocating. I'm not trying to claim that there was this big 12 million-person tribe that followed the mammoth around, and stampeded entire swaths of the herd off cliffs or whatnot (and then conveniently buried them, in easy-to-find locations, so that they'd preserve well).
quote: NO! Can you be any more frustrating? It's like I'm debating with a creationist who keeps on saying "Well, if precambrian life was so widespread, where are all the fossils???" Again, I will ask, and I want a response this time: Please explain *Why* you would expect to find a sizable percentage of the human and mammoth remains from this brief time period to have been recovered. Cite examples of where this has occured elsewhere. Now, for the LAST TIME: The lack of evidence isn't evidence itself, and never once have I claimed that. The finding of a few sites (what, 15 kill sites) is what is expected.
quote: Apart from the fact that humans *have* caused megafauna extinctions in recent history through overhunting. So, in short, your claim falls to "it can't happen on a continent" and the unsupported "we should find more kill sites", despite all of the evidence that we *shouldn't* find more kill sites, and that we're lucky to have found the ones that we did.
quote: Try a better criticism, that hardly stands. Bones are not ivory. Where are the bones? Nice job with your quote, BTW - you literally pulled one out of the creationist playbook: starting a quote where a person points out a criticism of their theories, and cutting off where they go on to show how the criticism isn't valid.
quote: Are you trying to claim that ivory hunters would take the time to burn the bones of the elephants that they hunted? If so, you're *really* stretching, Mammothus.
quote: Are you talking about what *modern* people are building huts out of? If so, how is that relevant at all to this discussion?
quote: How do you come to this conclusion? Name one place where I advocate that they just dumped the mammoths. I'm growing tired of these straw men. Are they intentional, or accidental?
quote: The preservation on that much-hyped mammoth has been, from what I have read, disappointing to say the least. And this is a mammoth that *wasn't* cut up, used as a shelter, and left to be pounded by the elements. I am rather shocked that you expect to find preserved shelters - and you have yet to explain why you feel that they would be preserved Let me turn your argument around: Where are the innuit artifacts through history? If you're expecting to find clovis shelters, there should be 10k years worth of innuit artifacts sitting in layers above them. Where are they all? You expect to find abundant clovis artifacts, so why not innuit? We find many clovis points, just as we find indian arrowheads. But we don't find indian shelters much at all. Again, though, you seem to have this weird notion that we should expect them to be preserved. Indians used bone tools, and all sorts of animal products. Why don't we find them abundantly preserved, like we do arrowheads?
quote: No, that's not the case. I was referring to your claim that you have evidence that "suggests not". I'm calling you on that evidence. What are you saying that you asked for an example of?
quote: Good job, Mammothus! You showed that there's not a bottleneck in African cattle. Now can we get back to the North American megafauna situation?
quote: Great job again! Old-world horses don't have a bottleneck. Again, can we get back to the North American megafauna situation? Why are you putting in these ridiculous, unapplicable sidetracks? Concerning the moose:
quote: Can you provide a link to the full text? BTW, a tight bottleneck isn't needed - just a reduction in population. Here's something I found on moose, which seems to indicate that there was a postcolonization bottleneck, at least among alaskan moose:
http://www.bioone.org...{Shortened display form of URL, to restore page width to normal - Adminnemooseus} quote: And now, we're back to old-world species...
quote: No. And you quite apparently can't show the opposite - thus, this point remains open to debate until better evidence can be provided. Let me know when you get your muskoxen data.
quote:quote: Sure. The original numbers that I used were 515lbs for a large moa, and 12,000lbs for a small mammoth. I meant to compare a large moa with a large mammoth - the ratio is actually far worse if you do that. Moa sizes:45-550 lbs.http://news.nationalgeographic.com/..._030911_moamating.html Mammoth sizes: Columbian, 16,000-20,000 lbs; Wooly, 12,000-16,000 lbs. So, comparing maximum size animals of both types, we get about 36 times bigger for mammoths, and comparing minimum size animals, we get 227 times. Regardless, the Moa is a far, far smaller animal, and will consequently be expected to have a more stable population given a certain amount of land.
quote: An island the size of Colorado? Certainly, one would expect a faster extinction given the smaller land area, but seing as humans could cause an extinction of a (proportionally) small, common animal on such an area, why couldn't humans do it on a larger area? Where do you draw the line, between island and continent? Does Australia count as an island or continent? By the way, you didn't address my question: Do you not know who the Anasazi were? Because I referred to the environmental destruction wrought by the Anasazi and Easter Islanders, and then you stated that island populations are different - which makes me believe that you don't know who the Anasazi were.
quote: There is no fundamental difference, only size. New Zealand is huge. So is Madagascar. Seing as there were no undesturbed continents left on Earth for us to study in the historic period, we can't witness, in real-time, a mass extinction on a continent, looking at what happened on the largest of islands is our best example. (by the way, when you quote something, please either italicize it ,quotation-mark it, put it in a quotation block, or otherwise distinguish it from your text)
quote: In Every Single Post!
quote: No. I have claimed that there is ample evidence of overkill in historic times even by "primitive" peoples, even on fairly large land masses, and named a bunch of other correlating factors that would tend to indicate that overkill was part of the extinction (different timings, by different peoples, in completely different regions, all resulted in the same result, for example). I cited that you don't need to hunt a species to extinction, only to weaken it to where it can't recover. I have stated that disease can play a part, either in finishing off a weakened species, or weaking a species so that other causes (such as hunting or habitat destruction) can take effect. What more do you want? The only region that I'm having to defend overkill is that you consider it to be *not* a factor, which is ridiculous given all of the observed incidents of overkill in history. You then put these preposterous levels of evidence that need to be recovered from the ground, ignoring the fact that we're talking about a very brief period, and things that one would never expect to preserve very well, across a massive expanse of land.
quote: False. The population models for the Moa extinction (which concide with the arrival of the Maori people and the last remaining Moa fossils) indicate only 160 years growth from a seed population of 100 people, with pessimistic assumptions about the number of moas and the people's birth rate, and optimistic numbers about the Moa's birth rate. There's no huge population being discussed, and yet it obliterated the Moa in no time. Keep in mind: In the North American extinctions, while humans had a low population density, so did much of the megafauna (proportionally).
quote: Not around. *During* We've got a, what, 2000 year window here? So, if you think clovis points were for scavenging, be my guest. How such a tool would be relevant for a scavenger is beyond me.
quote: What questions of yours have I not answered? There have been several that I have had to ask you multiple times.
quote: If you alter the environment of part of a migration route, that's catastrophic. If you alter the balance of species in a region, that can have a catastrophic effect (for example, destroying the top predators, leading to a boom of herbavores). If you harvest certain types of plants only, you can change the flora of a region. There are many different ways which can have major effects. Also, you seem to believe one would expect that all human cultures, over all of the Americas, over all of the time of the extinction, to be identical, despite completely different environments. Why?
quote: Are you claiming that there was an extinction prior to 12-14kya in recent geological history that was even comparable in size? Please, be more specific.
quote: I don't argue with this. However, the consistancy with which humans have caused mass extinctions of genera of large animals -directly or indirectly - wherever we have migrated to, is undeniable.
quote: Once again, you're ignoring the time frame. Humans arrived and mammoths dissapeared at about the same time. You have to compare contemporary mammoth remains only, or you distort the picture. Why do you keep doing this? Also worth noting is how Wrangel Island sheds doubt on the climate change theory, since their mammoths survived. Wrangel Island is also only 2,000 square miles - smaller than Delaware. One would expect the extinction to be fairly quick, regardless of which model you use.
quote: I just use 12 million as an example number because it is the number Mithen uses in his hunting-only model of extinction. With a multiple cause theory, the number can be quite smaller. The number of Native Americans in the Americas when Columbus arrived is unknown, but from what I have read previously (I can try and hunt down the numbers), it was estimated to be between 40 and 90 million - roughly 2.5 to 5.6 per square mile.
quote: This I've got to see...
quote: The cheetah is in horrible shape right now, it has almost no genetic diversity. This is actually a case where a disease-caused extinction could likely occur, if it weren't for the dispersion of cheetahs to zoos around the world. Some animals bounce back better than others; notice how you didn't address the passenger pigeon despite it being brought up. Why couldn't various kinds of megafauna need to live in a sizable population, as the pigeons did?
quote: How, exactly, are your cites supposed to suggest that there hasn't been a relative equilibrium when it comes to hunting cultural memes and prey adaptivity? If we're talking about moving back into an area where humans already are living, then they're going to be equally subject to fairly rapid selection factors if they overhunt. In the New World, it would take thousands of years for overhunting to catch up with them, because they can always just go elsewhere.
quote: Might I mention that we don't have any preserved siberian clothing, only needles carved from bone, in poor preservation? And yet, again, you are of the opinion that we should be finding worked hides or other similar pieces of evidence. Do you realize how vast and inhospitable Siberia is? It itself is about 5.2 million square miles. The coldest temperature recorded in the Northern Hemisphere is Verkhoyansk, with -96 F. While there is a brief growing season in the summer, and some regions are forested, the area as a whole is frigid and bleak. Due to this, it took humans almost 20,000 years to reach the Bering Straight. Clothing pretty much had to be invented by humans, in addition to other things needed to survive such frigid weather. If they haven't made it to a location yet, how do you expect them to cause animals to go extinct in it?
quote: Natives are selected against if they destroy their own food supply or other cultural requirements, just as the Anasazi were.
quote: Yes. But we had cultures filling up an entire continent here. Even if those who remained in Alaska reached a relative steady-state, it won't have any effect on those who are by then pushing down to Mexico. The Maori eventually reached a steady state too, you know.
quote: I said that it is possible for a culture in a (relative) steady state to go back to a destructive mode - social memes change, after all. But if they do, they themselves will be selected against.
quote: Do you realize that you've been parallelling the "God of the Gaps" theory this whole time? My argument is from evidence of hunting to extinction and severe environmental destruction by primitive tribes in recent history on quite large land masses, but you are focusing on a lack of evidence - for or against - in the past, where preservation is quite poor and not expected very often, and we're looking at a very brief time frame.
quote: And, for the most part, each of these different cultures has been in a relatively steady state with their flora and fauna.
quote:quote: Ah, my mistake, I didn't realize that you were referring to that paper. So, what "behavioral adjustments" do you suggest that they make to avoid humans? It's no simple task. Of course, I put the greater burden on the human side - what the humans tend to hunt, how they tend to hunt, how wasteful they are, what age/sex they target, how much of their diet is based on hunting vs. gathering, etc. (skipping a number of already addressed points)
quote:quote: This was in a discussion about shelters, so we're mostly talking about skin. How much skin has been found outside of the tundra?
quote: Very few would consider this a closed issue, myself included. However, judging from what we have observed of extinctions in history, overkill seems likely to be at least part of the cause. Let me know when you come into any evidence that, unlike overkill, overill has led to the extinction of a healthy species at any point in recorded history.
quote: Many, many islands.
quote: If you can manage to get such groundbreaking results, let me know. Until then, overill is really in tatters if you look at the historical record - we're only talking about disease wiping out species that were near extinct anyway.
quote: What, a combination of factors, which includes hunting? Guess whose position you just advocated there.
quote: Because there were no more highly inhabited 16 million square mile land masses after that, quite obviously. P.S. - So, Mammothus, how do you propose that extinction-causing hyperdiseases followed every major human migration into uninhabited territory, despite time or location, throughout history? ------------------"Illuminant light, illuminate me." [This message has been edited by Rei, 10-21-2003] [This message has been edited by Adminnemooseus, 10-21-2003]
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Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
You know, Quetzal, I'm not sure why we're debating here - we actually seem to agree on most issues related to this. My view is that many issues, of which hunting was one, led to changes in the flora and fauna in various regions, which in turn caused other species to decline. Some species weren't lucky enough to be able to recover. I assume that this is what you mean by your "disequilibrium" hypothesis.
I don't disagree that disease can have a strong impact. What I disagree with is the notion that a disease or family of diseases have followed every major human migration into areas that haven't seen humans before in history, in different time periods and geographical areas, and taken a diverse, large group of otherwise healthy animals, from completely different orders, and brought them to extinction each time. That really seems like a preposterous concept to me, not something that has been observed in the world. Can diseases weaken a population? Yes. Can diseases kill off an already severely weakened population? Yes. Can diseases alone cause what is witnessed at the end of the Pliestocene? Very doubtful. My main gripe with Mammothus on this front is that he seems insistant that killing had nothing to do with it. I disagree. The weapons used by the clovis culture weren't those of scavengers - they were those of hunters of large game. They had an entire continent to expand into, and plentiful food. It is only reasonable to expect a population boom. Is hunting the only reason? Of course not - the extinctions are too diverse for that. But hunting clearly is going to play a major impact on the environment itself. I also think it's preposterous to expect major amounts of preservation from such a brief time period 10kya. I hate the unreasonable belief that native cultures were somehow all in touch with the environment, and only modern humans have become destructive. It's not evidenced by history. P.S. - I still think it was unfair of you to pull out the second sentence of my first paragraph and hold it up alone, even though the sentence right after qualifies it. But that's beside the point. ------------------"Illuminant light, illuminate me."
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Speel-yi Inactive Member |
quote: Isotopic anylysis does suggest that Neanderthals had an almost exclusively carnivorous diet. It does not mean that they could not eat anything else. Nor does it mean that either of the groups would have had much of an impact on game in any event. There would have been plenty to go around for both and apparently there was for at least 10,000 years since we find remains dated from the same time periods. But in order for competitive exclusion to work, we have to have two species that are incapable of interbreeding. There is nothing to suggest that the two populations could not mate and produce offspring other than a pet theory. If they were two separate species, there is no reason to think that both could not have coexisted for another 10,000 years together. They did occupy slightly different niches and neither one of their niches were seriously depleted by hunting. ------------------Bringer of fire, trickster, teacher.
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Quetzal Member (Idle past 5872 days) Posts: 3228 Joined: |
You know, Quetzal, I'm not sure why we're debating here - we actually seem to agree on most issues related to this. My view is that many issues, of which hunting was one, led to changes in the flora and fauna in various regions, which in turn caused other species to decline. Some species weren't lucky enough to be able to recover. I assume that this is what you mean by your "disequilibrium" hypothesis. Well, I'd say we're debating because of your insistence that human hunting - while perhaps not the ultimate cause - was in fact a major proximate cause of the extinctions. I disagree. It's similar to the debate over the relative importance of natural selection, etc, in evolution. Your assertions concerning the ability of paleoindians to effect mass destruction of continent-wide populations of megaherbivores and (indirectly) their predators is unsupported, and I think unsupportable. You're also using an inappropriate analogy of island extinctions (or the destructive practices of restricted populations such as the "Anasazi") to extrapolate to the wider continents-wide hecatomb of literally millions of organisms in a very brief period which is contraindicated by the available evidence. Finally, your argument concerning behavioral/cultural (meme) evolution in paleoindians has not been well-developed (in this case, you need to provide more detail on the argument, including what evidence might lead one to suspect that this occurred). That is why we are debating. The disequilibrium model is an ecosystem-level approach deriving from the concept of ecosystems as complex adaptive systems, and owes more to the "overchill" hypothesis than anything else. Admittedly, it is also based on extrapolation from small-scale observation to continent-wide effect (as I accused you of doing in error), but rests on the foundation of the known severe changes in the continental biome and floral turnover at the end of the last glacial maxima, which makes it different than your extrapolation because it rests on verified evidence. Nobody apparently is interested in discussing it.
I don't disagree that disease can have a strong impact. What I disagree with is the notion that a disease or family of diseases have followed every major human migration into areas that haven't seen humans before in history, in different time periods and geographical areas, and taken a diverse, large group of otherwise healthy animals, from completely different orders, and brought them to extinction each time. That really seems like a preposterous concept to me, not something that has been observed in the world. Can diseases weaken a population? Yes. Can diseases kill off an already severely weakened population? Yes. Can diseases alone cause what is witnessed at the end of the Pliestocene? Very doubtful. I don't think anyone other than MacPhee and his group is arguing that "overill" is the sole cause. Mammuthus certainly isn't. Even MacPhee, to be fair, is only concentrating on it exclusively because, according to him, "in many instances the adoption of a multifactorial explanation is really an admission of defeat rather than a breakthrough in understanding" (from MacPhee 1997, cited by Mammuthus above, pg 209). Along with the role of EID in wildlife population declines studied by Daszak's group and a very few others, IMO understanding the potential of disease to effect widespread diverse populations has significant implication for modern biodiversity conservation - and even for human pandemics. We ignore that at our peril. The only potential example for this is the highly selective extinction event that occurred in the Late Pleistocene. So I think it's worth exploring. Dismiss it if you will - but provide more comprehensive argument against than you have so far.
My main gripe with Mammothus on this front is that he seems insistant that killing had nothing to do with it. I disagree. The weapons used by the clovis culture weren't those of scavengers - they were those of hunters of large game. They had an entire continent to expand into, and plentiful food. It is only reasonable to expect a population boom. Is hunting the only reason? Of course not - the extinctions are too diverse for that. But hunting clearly is going to play a major impact on the environment itself. I also think it's preposterous to expect major amounts of preservation from such a brief time period 10kya. Actually, I tend to agree with him on this overall. For example, in all of the southwestern sites associated with Clovis, there is only ONE that I can remember (and I forget which, specifically) that has any remains of sloths like Megatherium and Mylodon. Since the former's preferred habitat was the juniper scrublands of the American southwest and Mexico, I find the lack of remains associated with the known kill sites in the area to be problematic. Additionally, the hunting idea begs the question of the disappearance during this extinction pulse of all of the various bird species - which nearly number as many species as the megafauna - that ALSO disappeared. And not flightless rails like the ones that went extinct on islands. These birds include raptors, scavengers, etc. Also, the minifaunal extinctions that happened at the same time are unexplainable by hunting pressure. It might - and in fact has been - argued that these are secondary or tertiary effects of the megafaunal extinctions (given how proboscideans in Africa substantially alter ecosystems), but that is highly speculative and as yet unsupported. I don't consider it preposterous to expect more evidence. Only Martin's blitzkreig takes it as a given that no evidence will be found because of the speed of the process. Given the number of well preserved mammoth hunter sites in Eastern Europe and Eurasia, I find it odd, as does Mammuthus apparently, that there are so few unequivocal sites in America - where substantially more and varied critters were supposedly destroyed.
I hate the unreasonable belief that native cultures were somehow all in touch with the environment, and only modern humans have become destructive. It's not evidenced by history. As do I. However, that doesn't mean I'm going to seize on the opposite extreme without evidence. Which, in this case, is lacking. I'll gleefully cite early Polynesian, Malagasy, Maori and even "Anasazi" destructive habits whenever the subject comes up. But only in cases where there is evidence to support it.
P.S. - I still think it was unfair of you to pull out the second sentence of my first paragraph and hold it up alone, even though the sentence right after qualifies it. But that's beside the point. Whatever.
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Mammuthus Member (Idle past 6475 days) Posts: 3085 From: Munich, Germany Joined: |
quote: You care to provide evidence for this assertion?
quote: Nope, I expect exactly the opposite. Mammoth fossil distribution spans several continents for this time period. Human fossil finds are scarce. I expect from the fossil EVIDENCE that mammoth herds were widely distributed. Humans were sparse..you claim that this is enough to wipe out every last individual mammoth without leaving any evidence of such a massive slaughter...and virtually every mammoth bone found showing no evidence that it was butchered.quote: Yes they did leave behind massive kill sites Emuseum – Minnesota State University, Mankato And no, unlike mammoths, they did not even put a dent in the buffalo population even though they were hunting them and they were contemporanous megafauna..and they were abundant...where is that negative selection pressure against overhunting? You like the world preposterous..that you considere me a fool for not accepting a hypothesis that flies completely in the face of what little evidence there is is preposterous.
quote: That is not the scenario I am advocating either. However, I would expect way more fossil finds with butcher marks (though these are hard to distingish from environmental damage), I would expect to find more sites (even without necessarily other evidence of human presence) with bones from multiple individuals in a non random arrangement like is found in Siberia (where it is less likely to be observed because of the ground shifting and dislocating fossil sites).I am not cliaming that little paleolithic time capsules had to be left around for us to discover. However, almost all the mammoth finds (and there are not one or two or few, there are thousands) show no evidence of death by hunting from any time period.
quote: If it makes you feel good about yourself to be holier than thou then enjoy yourself. You have also been arguing like Fred Williams when he makes a statement like "transposons disprove evolution" and then claims his oppositoin are biased idiots for not being in awe of his wisdom. First off, why do you expect 15 sites (only 4 of which apparently are widely accepted)? Why the number 15?Mass kill site ARE found for other species like buffalo..there are even sites identified where smilodon killed off mammoths over a long period of time....but almost no hunting evidence for the species that went extinct even though there are thousands of fossil finds throughout eurasia and North America. Wouldnt you expect to find more sites? Even a hundred sites? Widely distributed throughout the areas where all this hunting would have to have occurred? If you can find evidence for the presence of humans in all of these areas..why not any for the mammmoths they supposedly lived off of? I don't think I am asking for too much...or do you think the overkill researchers should stop looking for more sites because 15 supports it so well?
quote: ALL the evidence? That is exactly what you have not provided or were you about to post how not finding corroborating evidence is an ideal source of support for a hypothesis....the creationists will be thrilled to learn this.
quote: You clearly do not like debate and expect people to fall at your feet in awe....Let's see how many more times the name calling can continue...do you have a case or do you get a high from calling me a creationist? Fine, do you want me to post Haynes handwaving and dismissal of any criticism of overkill or should I just cull the text from one of your posts?
quote: And you are stretching like a rubber band is you think that elephant culls are done by illegal ivory hunters..LOL!
quote: What are you talking about with modern people? http://www.hominids.com/donsmaps/mammothcamp.html
quote: You claim on the one hand that a single mammoth could sustain a group for an extended period yet they kill ALL the mammoths i.e. overhunt (even though humans are dispersed and have alternative prey sources)..so they would have had excess mammoth that could not be stored, could not be eaten i.e. waste, dumped...if your arguments are not consistent with reality don't blame it on me.
quote: Because preserved shelters are found in other places but never in the relevant places or times for overkill.
quote: I would say it argues that there were not a lot of them around. Massive populations would be expected to leave behind lots of artifacts, smaller and sparse populations not so.
quote: You do realize that horses originated in the new world? Why is this not relevant. If the hunters were putting pressure on all the megafauna (and mammoths became exinct in europe as well) why are ALL of these megafauna showing no sign of a genetic impact? How convenient for you to claim that evidence against your position is an irrelevant sidetrack when you brought it up in the first place! YOU CLAIMED that the hunters ALSO probably hunted these other species but the evidence from genetics strongly suggests that it had absolutely NO impact on them genetically..there is no trace of hunting pressure on alternative widespread megafaunal food sources...even for ones like buffalo that we know were hunted. Yet, these people picked and chose to slaughter every single last mammoth, multiple species of giant ground sloths while selectively avoiding having an impact on all of the other abundant megafauna...to use a word you love so much..preposterous.
quote: So the animals that went extinct should show a bottleneck but other animals such as buffalo which are relevant, canids are relevant, moose are relevant, horses are relevant for eurasia where the extinctions also occurred and north america where horses were also present should show no impact from hunting even though you claim that they were probably also hunted? I have supported that none of these (irrelevant to you since it goes against what you want to see) species do not show evidence that their populations were put under pressure at the time that many other megafaunal species were being exterminated..even though they were being hunted as well in some cases. It is up to you and the other overkill zealots to explain why they were not affected.
quote: considering how many points of mine you blow off as irrelvant I guess I should be pilloried because I missed one of yours...Here I will help you "Mammuthus, because you disagree with me you are like a creationist"..feel better Rei? Last I heard, Easter Islanders were on an island so my question stand. Any evidence that the mass environmental damage (by these small concentrations of people widely dispersed) was continent wide like the Anasazi?
quote: Why expected to be more stable? Are island populations more or less stable than continental. [This message has been edited by Mammuthus, 10-22-2003]
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Mammuthus Member (Idle past 6475 days) Posts: 3085 From: Munich, Germany Joined: |
quote: No fundamental differences between islands and continents? You sure about that? And why can extinction only be examined at the island level? That is certainly not where most Pleistocene extinction work is concetrated so even the people you are so strongly supporting would disagree with you.
quote: Aha, so we are sinking to attacking post format..fine I'll do that if you start spelling my name correctly.
quote: For someone showing such concern to be seen as supporting a mixed approach you certainly have done nothing but try to defend every single aspect of overkill as a rock solid supported fact and all alternatives as utter bullshit unworthy of even cursory consideration...so forgive my confusion...Quetzal must also be dim since I see he also suggested that it is unclear from all of your posts that you advocate anything other than overkill as being the single most important factor.
quote: No, I have not said that hunting was not a factor. I have said that overhunting has very little support as a primary cause of the end Pleistocene mass extinctions. And that without supporting evidence I will not accept it as the explanation for end Pleistocene mass extinctions. I hold overill and overchill to the same standard. All three must be further studied and at present virtually no conclusions can be drawn. You have been arguing since your first post as if overkill is a fully supported hypothesis which it is not.
quote: Why false? They did leave a trace unlike in the case of continental megafaunal extinction.
quote: where have I advocated a monolithic culture? You were the one proposing it for Africa and implying it for the new world. Beringia was completely ecologically remodelled by the environmental change that allowed people to cross into North America in the first place unless you propose clovis used their points as snow plows. Where is the evidence that the grassland expansions and seasonal vegetation fluctuations or the change in flora locality as discovered empiricallyPoinar HN, Hofreiter M, Spaulding WG, Martin PS, Stankiewicz BA, Bland H, Evershed RP, Possnert G, Paabo S. Related Articles, Links Molecular coproscopy: dung and diet of the extinct ground sloth Nothrotheriops shastensis. Science. 1998 Jul 17;281(5375):402-6. Was human induced?
quote: Though there were mammalian extinctions the Pliocene Pleistocene boundary extinctions were mainly marine. You wrote your sentence implying that mass extinction could only be associated with humans. It is not and extinctions have occurred consistently and cyclicly even before H. sapiens evolved.
quote: But this does not get us anywhere in determining whether they were a cause. I could just as easily say that the spread of multiple species and speciation has also depended on animals following or hitching ride with humans such as Drosophila melanogaster.
quote: And once again you are merely dismissive of any counter evidence or logical flaws in overkill of mammoths on Wrangel..but yes, Wrangel is a huge problem for climate as a singular or even a key cause of mammoth mass extinction at least.
quote: You could have found these yourself but Martinez-Laso J, Sartakova M, Allende L, Konenkov V, Moscoso J, Silvera-Redondo C, Pacho A, Trapaga J, Gomez-Casado E, Arnaiz-Villena A. Related Articles, LinksHLA molecular markers in Tuvinians: a population with both Oriental and Caucasoid characteristics. Ann Hum Genet. 2001 May;65(Pt 3):245-61. Tokunaga K, Ohashi J, Bannai M, Juji T. Related Articles, LinksGenetic link between Asians and native Americans: evidence from HLA genes and haplotypes. Hum Immunol. 2001 Sep;62(9):1001-8. There is more but you can find it yourself.
quote: But the cheetah is not extinct..niether are elephant seals..both mammals. What exactly do you want addressed about the passenger pigeon? That humans can cause extinction? Where did I say they cannot or have not?
quote: You claimed that Africa was in equilibrium..it was not. Now you switch to something else about overhunting. Ok, where would the people move to in the new world? Once they caused these mass extinctions there would have to be people everywhere that the mammoths went extinct..which was everywhere. How would they move back or around without encountering other people? Or are you now proposing that it was a single group moving around North America to patagonia (even though genetically it looks like multiple waves of people from different places colonized the new world).
quote: Blink blink..what did you say? So the finding of carved mammoth bones and shelters in Siberia suggests that humans had not made it there yet? Siberia was colonized long before the new world.
quote: Why only skin? The Siberian finds are clear with mostly bone.
quote: Yes, as opposed to that wonderful solid foundation of evidence for overkill that you and its supporters have provided.
quote: citations please.
quote: Unless you are purposefully not reading my posts (which I think in this case you have done intentionally) I claimed that I am not wedded to any of the three hypotheses. I made it clear and I have made it clear why. You have not. You should be careful about calling me a creationist when you are ripping off their debate tactics yourself.
quote: So you admit you have never read the actual primary article that described the hyperdisease hypothesis...very interesting.
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NosyNed Member Posts: 8996 From: Canada Joined: |
Boy, you guys!
I have not disected each post really carefully but I will still put forward my opinions. My comments on this interesting discussion are:1. You both seem to be talking past each other. I think you all agree that a combination of factors was probably responsible. 2. There doesn't appear to be enough evidence to support any firm conclusions. You both seem to make statments about a variety of things without evidence. As I understand Mammuthuses position he is trying to look at an hypothesis that *might* have evidence for it. He is *not* trying to look at all possible causes. His work would then be integrated with other work to try to arrive at a bigger picture. However, given the amount of thought you've all put into this, my opinions may be the least valuable input in the thread.
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wmscott Member (Idle past 6247 days) Posts: 580 From: Sussex, WI USA Joined: |
Dear Mammuthus;
You made a convincing case on the genetic diversity, this of course requires that many individuals of the surviving species lived through the extinction event while the Musk Ox were not so lucky and made it by the skin of their teeth with perhaps just a single breeding pair. This does complicate matters, for how so many could survive when so very many died, it would be so much easier if the surviving species had very little genetic diversity due to there being very few survivors, then we could just write it off as luck of the draw. But it now seems that in the extinction event there were strong selective factors at work. It would be interesting to deduce what caused the pattern of extinction. The amount of genetic diversity in each surviving species would point towards what it was that caused some animals to be at far greater risk than others, for we know the habits and traits of the surviving animals much better than the ones who went extinct. I hope you do find a 'Taimyr mammoth dating to 4500', it would be great fun and just perhaps you may find one. I am very pleased that you agree with me on the demise of Neandertal, but in light of the large scale survival that many animals genetic diversity reveals, it deepens the mystery of how they could have been so selectively destroyed. How do you kill a bunch of Neandertal without killing off the modern animals? Funny about the rejection of DNA for cro magnon, I would expect cro magnon to have very nearly a modern DNA sequence. Dating on the late glacial marine transgression is after the glaciers retreated from southern Wisconsin probably after about 14k, but probably before about 10k or 9k. What I have is a thin layer of marine diatoms near the soil surface. The layer is not present beneath the glacial boulders or deeper down in the soil, but I have found one case where the layer is present beneath a large boulder. This rock was apparently placed on top of the diatom layer without disturbing it, which implies that it was floated into place and dropped from melting ice. The rock is very simular to one laying just a few feet away, they both appear to be from the same source, which would indicate that the glacier that had deposited the one rock, had not retreated too far to the north, or the second rock would probably have been from a different source. So far, I have only processed samples from my local area. My old lab processes were labor some and had a low collection rate, I have been working to improve the process and I believe that I now have a much improved method that will allow me to process more samples and test more areas. Supporting evidence from elsewhere includes things like dropstones in none glaciated areas, such as in the Wisconsin Driftless Area by the Mississippi river. Apparently the glacial super flooding which created the river's oversized flood plain, backed up over the Bluffs and dropped rocks from floating ice over the surrounding landscape. Ice damming is pointed to as the cause by some, but no secondary channels were cut nor other erosion evidence formed by flood waters flowing around a Giant ice dam. The land is fairly flat and such erosion would be expected, which has caused some to write off the drop stones as from an earlier glacial stage or left by man. There are of course other evidences from all over the world which point towards a recent marine flooding, but each is always attributed to other causes or sometimes even ignored. Since I am not going to prove my case by using evidence which is already been shelved, I am concentrating on the marine diatom layer since it is new and mapping it's extent which is probably global, would be pretty clear cut evidence. You have aroused my interest in the genetic diversity of living animals and genetic clocks, could you recommend a few good books on the subject? I have read a bit on genetics but my knowledge is limited, so the advanced books would probably be over my head unless the authors are very 'readable'. Wm. Scott Anderson
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Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
quote: If you want me to quantify it, I'd put it at about 20-30% relevance.
quote: Not just killing of herbavores, and indrectly causing their predators to die off. Killing of both predators and herbavores, in addition to altering the flora; this indirectly causing instabilility which leads to more die-offs, and this in turn leading to more instability... etc, until a new steady state can be reached.
quote: 1) I'd hardly call around a hundred kilometer radius "restricted".2) I'm not saying that the entire continent was deforested. It was just an example of continental populations causing local environmental destruction. quote: Well, in the case of the Anasazi (an easily documented example), wouldn't you say that they were selected against, while the Pueblo were selected for? Also, what model would you propose for memes not having an effect?
quote: Then I would like clarification from Mammothus on just what he's advocated. Despite being continually pigeonholed into "overkill-only", I have in virtually every post explained that I do not consider overkill-only to be the cause, but instead a variety of factors (of which overkill is one: overkill, overill, overharvest, overlogging, climate change, introduced species, and the ramifications of all of these magnified through disequilibrium).
quote: Highly selective? Unless your selection criteria is "large", I don't know how you come to this conclusion. On a quick search, 95% of large herbivores (>2 tons), and 73% of genera of animals weighing 44kg or more, went extinct in North America.
quote: While some dates are still up in the air, it *does* appear to have been a very fast process, whatever killed them; in Europe, and Asia, it doesn't. And the key issue concerning whether the amount of evidence is what is expected or not is the speed; all debate on this topic hinges on that. P.S. - why do you keep putting "Anasazi" in quotes? Would you rather I refer to them as "ancestral Puebloans"? ------------------"Illuminant light, illuminate me."
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Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
quote: What are you thinking is preventing such a population? The Americas had notably more Native Americans than that when Columbus arrived, so it clearly could support that many *without* the megafauna. Do you think population density is a problem? Hardly, that's less than one person per square mile. Do you think transportation times are a problem? Hardly - not only do we find plenty of evidence that they *did* travel down the coast to southern South America in short time, but the distance - 10,000 miles - would be only 5 miles per year (a tiny rate, really), given 2,000 years (yes, I know about how the Monte Verde is dated to 12,500, but we're going to just operate on the figures being used: 2,000 years to populate the continental *interiors*, as opposed to just the coast). Do you think growth rates are a problem? Hardly - using simplifying assumptions (a growth rate of 4 children that survive to adulthood per woman, assuming they're all born at age 20 and then the woman and her husband dies, etc) so that I can calculate quickly, in 2000 years you would have 100 doublings of the population, so an initial crossing of 1,000 people would reach 1.3e33 people if given infinite resources and infinite land. Clearly biological constraints for reproduction aren't a problem here, the issue is resources - how many people are there resources to provide for. Which was the first point addressed.
quote: Which is exactly what I'm saying: With the mammoths spread out, the humans will be spread out as well - I.e., small bands, even though the total population would be high. Are we clear on this now? ... You know, these are getting longer and longer. My last response took something like 2 hours, and this one may end up being even longer. I really don't have time for this today, I'll try and catch up tomorrow. ------------------"Illuminant light, illuminate me."
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Quetzal Member (Idle past 5872 days) Posts: 3228 Joined: |
If you want me to quantify it, I'd put it at about 20-30% relevance. ------- Not just killing of herbavores, and indrectly causing their predators to die off. Killing of both predators and herbavores, in addition to altering the flora; this indirectly causing instabilility which leads to more die-offs, and this in turn leading to more instability... etc, until a new steady state can be reached. I'm not clear how you derived this figure (off the top of your head?). In any event, the key difference between our positions is in the second paragraph: I don't consider the paleoindians to have figured very prominently at all in the extinctions. At worst, they were an additional factor - whether through disease or hunting - rather than anything remotely causative. The point being there is no evidence that they killed large numbers of megafauna. Local family groups probably. Extinction of localized population remnants possibly. Small numbers thither and yon, definitely. Tens of millions of organisms to the point of continent-altering ecosystem damage? Unlikely, and unsupported by the available evidence. In spite of finding thousands of dead mammoth scattered about, the record is a text of "random" death with little artifactual association, rather than non-random (as would be the case with human hunting being a factor. Martin explains this anomaly away by claiming that the speed of the slaughter was too fast - which I don't consider compelling in the absence of corroborating evidence. Basically, you need to a) explain what evidence you would expect to find if your idea was correct; and b) provide specific examples that support your point.
1) I'd hardly call around a hundred kilometer radius "restricted". 2) I'm not saying that the entire continent was deforested. It was just an example of continental populations causing local environmental destruction. 1. You're not serious? Martin's blitzkreig requires a minimum population starting at 100 individuals (sound familiar in reference to the Maori?), migrating across the continent at a rate of 20 miles per year (I misquoted before, I'd said km - I just re-read his paper, and it was miles, not kms), with a population doubling every generation due to over-abundant game. 100 kms is NOTHING compared to what you are suggesting for the paleoindians. It is totally not beyond even my comprehension to believe that the Maori were capable of decimating every single population of naive organisms as rapidly as they did in such a tiny space. No refugia, a central mountainous area that was inhospitable to most of the moa (from my understanding), a restricted geographical area with no place to go. This is waaay different from a continental landmass with its myriad of possible refugia, etc. 2. Good thing. And I'm aware that they caused severe degradation/desertification in their zone. However, the point is it WAS restricted, it WAS localized, and we have NO examples from paleoecology where a continent was effected at the same level by humans. Your extrapolation is invalid, as there is no foundation for the assertion of equivalency.
Well, in the case of the Anasazi (an easily documented example), wouldn't you say that they were selected against, while the Pueblo were selected for? Also, what model would you propose for memes not having an effect? Sounds suspiciously like you're shifting the burden of proof here. You tell ME what YOU would expect to find, and then provide examples. It's your hypothesis. Why should I develop a model for something I don't agree with? Try this: what leads you to think it's valid? Just 'cause it sounds good and you read something about memetic evolution somewhere? C'mon, Rei, you usually do better than this.
Highly selective? Unless your selection criteria is "large", I don't know how you come to this conclusion. On a quick search, 95% of large herbivores (>2 tons), and 73% of genera of animals weighing 44kg or more, went extinct in North America. Yes, selective. The event took out the top, a few bits from the middle, and substantial bits from the bottom. Yet it left a huge chunk of the middle untouched. This pattern is totally inconsistent with hunting pressure being a significant factor. That means something else happened.
While some dates are still up in the air, it *does* appear to have been a very fast process, whatever killed them; in Europe, and Asia, it doesn't. And the key issue concerning whether the amount of evidence is what is expected or not is the speed; all debate on this topic hinges on that. Speed is certainly one of the main factors. However, I'd say the extinction pattern itself is a more critical factor that needs to be addressed by any of the three leading models. None of which have done so very well, at this point.
P.S. - why do you keep putting "Anasazi" in quotes? Would you rather I refer to them as "ancestral Puebloans"? I put "Anasazi" in quotes because I am unconvinced they represent a distinct and separate culture from the other southwestern tribes extant at the time. Puebloan is probably more accurate. IT's an affectation - don't sweat it.
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Mammuthus Member (Idle past 6475 days) Posts: 3085 From: Munich, Germany Joined: |
I would say you have nicely summarized in a few sentences what Rei, Quetzal and myself have debated in novel length posts...so hardly a useless contribution Nosy.
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Mammuthus Member (Idle past 6475 days) Posts: 3085 From: Munich, Germany Joined: |
quote: Then why is there no evidence of such exponential population growth until the last 200 years? Can you name a hunter gatherer group that expands at such an enormous unlimited rate and sustains it?
quote: I understand what you are saying. I just dont agree with it. Mammoth finds do not show such a sparse pattern in their distribution. Human finds from this period do. Why are only mammoth and animal finds so readily availabel if humans are in similar numbers? And I am not sure that there is much of a point even trying to make a population density statement for either the megafuana or humans from the fossil record as it requires pulling numbers out of the air and is not falsifiable with the data that has been accumulated to date.
quote: Amazing! We agree on something. I have meetings all day and don't have very much time for this today either.
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Mammuthus Member (Idle past 6475 days) Posts: 3085 From: Munich, Germany Joined: |
quote: 1. I submit that overkill, overill and overchill are all hypotheses with very little support, are thus mostly theoretical models, that each alone does not account for extinction, and that substantial evidence will be required for each before any can be supportably claimed to have been an important factor in end Pleitocene extinctions. All three may ultimately fail with something unexpected and thus far not postulated better explaining the event. 2. In studying quantitative trait loci genetically, it is completely unhelpful to say, "well environment plays a role, multiple genes, epigenetics, etc...no one gene is responsible". One has to isolate as many variable as possible and map each gene contributing to the trait individually. Similarly with overkill, overchill, and overill...it is completely (in terms of gathering evidence) useless to claim that everything together contributed to mass extinction. Each hypothesis must be tested individually. I do not expect an overkill supporter to have to do mass sampling of pollen to look at climate change in regions where they are searching for kill sites. So I would say each group looks for evidence that supports would support (or refute) their hypothesis regardless of whether or not they think it is a multi-cause event. Where you and I disagree is you equate the theoretical arguments of overkill with fact. Without supporting evidence for the mass kills you claim this is not detrimental to the hypothesis yet if no novel pathogens have been found in the last sum total of 3 years from two guys and about 50 fossils, overill is "in tatters" (to quote you) and every example from cimate you have been equally dismissive. Yet in over 30 years by multiple groups (being generous since fossil collection has been going on for much longer) 15 kill sites have been found, 4 of which are convincing...if anything, the climate theory researchers have gathered the most evidence but have problems with the synchronous extinction event and asynchronous climate change. Given the paucity of supporting evidence for overkill I would then say all three groups hypotheses are "in tatters". So I think my position should be relatively clear now. And where our conflict has been as well. You can tag at the end of each of your posts that you think it is multicausation, but you argue throughout your posts as if all aspects of overkill support are fact when most of the arguments you have presented range from debatable to completely unsupportable. edited to add: Rei, I apologize that our posts to one another have been so acrimonious. I will endeavor to tone mine down. Cheers,M [This message has been edited by Mammuthus, 10-23-2003]
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Brad McFall Member (Idle past 5032 days) Posts: 3428 From: Ithaca,NY, USA Joined: |
I'm going to go out on a Gould leg thanks to S&R's talk back to me here on EVC and suggest that a threefold synthesis divided twice among amphibians, reptiles, birds, placentals, all other warm bloods will by using AGE AND AREA for the first cut and compeition caused climatically BECUASE of warm blooded extensions to the age and area relations ancestral that the locations of the "kill sites" may be circuscriptable. What I have in mind is that by using the marsuipals for DATA on the extenst of variation, molecular biology evidence, will show increaingly tight coordination of birds transforming in this MESO evolution from mammals the proximate cause being the changes in metabolism acompanying warm-bloodedness but it will be the environment and not locomotion that extends the area outside of a correlatable age and area issue whereas it will be THIS compeition for energy to move (not the motion per say) that enables the Saber Tooth Tiger eating Turkeys to BECOME the Bald Eagle eating Rodents on the basis of a marsupial panbiogeographic local geographically and in a variety of different kinds of genes that will have a landscape to the various ways that warmbloodeness can be sustained by INCREASING the distance the young OUTSIDE have to travel before growth. Placentals = 0, Marsupials = small amount Birds = large amount( eggs in nest which may not be where the parent feeds). This would also explain why there was no focus on my understanding of herpetology when it came to becomeing an evolutionist at Cornell. Whether this sabertooth will turn into the rodent ecologically in a small number of generations or the birds find ways to seperate from the space of the marsupials may not be what the evolutionist expects but I am preliminarily goning to follow this change thought up and I would like to thank Saymsu and Randy for reading thu my spelling errors and sticking up with me to this point.
If there are other causes of the kill sites they should be isolatable should this non-traditional approach apporach the unconditioned all the time as well.
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