Overkill, Overchill, Overill? Megafaunal extinction causes

Dear Mammuthus;The overkill theory is unworkable I agree, but I find that the "overill" theory sounds too much like magic to me, with effects that produced just the opposite results as what would be expected. Things like maximum effects in the areas affected the least by ice age man, many animals wiped out in the new world survived in the old world. Generally man is pointed to as being the carrier of some super 'bug' that could wipe out huge animal populations and yet it didn't harm man or the animals in other areas. Modern man shows no traces of this super bug, and there is no record in history of new species being wiped out by a human carried disease upon discovery. This super bug also left no trace of itself in fossil evidence such as bone scarring, poor health, slow growth, deformity, etc, and so far DNA testing of modern populations and ice age remains has turned up no trace of it at all. Admittedly finding the DNA bug would be very hard, but the complete lack of evidence and considering the conflicting evidence, the 'overill' theory sounds to me like a flight of fancy that flies through the air without any support at all.I favor a variation of the 'overchill' theory, a run away deglaciation event that resulted in a temporary rise in sea level that resulted in wiping out many animals, or as it is more commonly known as, the biblical flood (minus all the absurd YEC theories of course). Whereas the 'overill' theory has no supporting evidence, there is evidence that supports a recent flood of global proportions. Much of this evidence has already been extensively discussed in the "Solving the Mystery of the Biblical Flood" threads, and while you are still looking for your smoking gun, I have already found mine. I can look through my microscope and see marine diatoms left behind by a recent very large marine transgression. This puts a recent global flood ahead of the 'overill' theory in terms of supporting evidence. A late Ice Age flood also has the advantage of more easily accounting for the patterns seen in the die offs, considering the effects large floods have on the types of animals that are killed and those that tend to survive.On a side note, let me say that I have been very impressed with your posts and I am very interested in any supporting evidence you may have for the 'overill' theory.Wm. Scott Anderson

Dear Mammuthus;I am astounded that work as important as yours is so severely neglected and underfunded. I think you are probably barking up the wrong tree, but how will we ever know unless you are able to find out? I would very much like to see your work completed, I would like to know if you are right or not. With the fossil DNA problem, you should consider the fact that under your theory, the living things today are all survivors and have all been exposed. your super bug if it was as deadly as you believe, it would have had to have been very contagious. Which would imply that nearly all living things carry it today, or at least the ice age carriers still would. It would have to be one of those bugs we carry that is today considered harmless, and is easily transmitted to nearly all animals. If you could identify a candidate bug, you then would have a target to look for in your DNA studies. It would have to be nonexistence and then have to suddenly appear at the right times and places. But I do find some fundamental problems with the 'overill' theory, like the lack of a historical account of one of our harmless bugs we carry, wiping out a species on first contact. Surely there would be an account of how when the first settlers arrived on a remote island, nearly all the animals suddenly died. Yet none of the island people tell of such a tale, and the island extinctions we do know of in historical times all clearly have other causes. I consider this very possibly a fatal flaw in the theory, since these first contacts failed to produce an 'overill' event as it should have under that theory.On the problem of climate change being asynchronous throughout that period yet extinctions were simultaneous, a sudden abrupt large rise in sea level would of course be simultaneous all over the world. Simultaneous extinctions are easy for a flood model to deal with, the problem is with progressive extinctions that are believed to have occurred over time towards the end of the ice age. But we must be careful not to over simplify, before the flood event there may have been other factors at work, perhaps even your super bug, that may have caused a number of extinctions. There may have been smaller abrupt changes in sea level leading up to the big one, that caused some extinctions in animals who's habit was limited to low elevations. Plus we have to remember that there is some noise in the data and what may appear to have been asynchronous may have been simultaneous. The surviver problem is solved by remembering that there would have been scattered 'islands' of survival. North America seems to have been particularly hard hit, many of the large animals that we have today are actually recent arrivals from the old world. The ice age humans didn't do any better, take a look at the difference between ice age skulls and modern populations in those same areas, the modern populations are nearly always the result of later migration. As demonstrated by the complete lack of Neandertal survival and complete lack of even their DNA in modern populations, there was a human bottle neck as well. The extinction event hit the hunters as well as the hunted, which throws a monkey wrench into both the overkill theory and the 'overill' theory as well.Wm. Scott Anderson

Dear Mammuthus;I am very glad to hear that others are interested in following up in your area, your work is far too important to be neglected.The expansion of the grasslands in North America and other changes around the globe are of course result of climate change and possibly also the influence of changes in grazing animals. On the extinction of the Pleistocene large animals while the buffalo increased, the absence of competition would have resulted in explosive growth among the survivers and establishment of a post ige age simplified ecological balance. The buffalo survived and exploded, the apparent lack of genetic bottleneck maybe the result of comparison with animals which may have suffered the same crimp in their populations, our yardstick may be bent or sufficient surviving diverse groups prevented the formation of a bottleneck. The Wrangel Island Mammoths may represent an isolated pocket of survival, some animals may have survived on floating ice. The Wrangel Island mammoths may represent the out come of a bad roll of the dice for the mammoths, if the supposed drifting mammoths had grounded on the nearby Siberian coast instead, perhaps they would be nearly as common today as they were in the Pleistocene. On the other hand, perhaps there is just a dating problem that has created the paradox of the Wrangel Island mammoths. I am suspicious about the precision with which we know when certain events occurred in the past. Like the 20k gap between the disappearance of Neandertal and the end of the Pleistocene, I find it more plausible that considering the scarcity of Neandertal remains that we are just missing some from that time and they were killed off by whatever killed off the animals rather then creating a second mystery on how they disappeared as well. How could they just disappear and take all their genes with them? The idea of Homo Sapiens Sapiens taking out Homo Sapiens Neanderthalensis is ridiculous, the average Neandertal could have taken the average Sapiens and twisted him into a pretzel. With greater brain capacity and much greater strength, Neandertal had a huge advantage, thinking otherwise is simply pure sapiens arrogance. Without the effect of the Pleistocene extinction event, I would have predicted the opposite out come, which means we may owe our very existence to this past event.Neandertal may not just be a old world problem, the Clovis spear points found in North America are similar to points used by Neandertal hunters in Europe, one source in talking about some bone fragments found in the state of Nebraska states. "probably ten or twelve individual skulls represented in this loess bone bed and that comparison shows them to be of the Neanderthal type, with thick cranial walls." (The Cambridge Encyclopedia Of Archaeology, p.100?) Evidence such as this and the scarcity of humanoid fossils points to the very real possibly that the Clovis artifacts are of Neandertal origin. Then there is also the Australian ice age population that consisted of two groups, an "ultramodern" group and a "robust" group with features that seem to have a possible Neandertal type influence. Then both these groups disappeared without leaving any descendants. "Examination of these Pleistocene remains has shown that all of them lie outside the range of contemporary Aboriginal skeletal variation, but in two very different directions." (The Cambridge Encyclopedia Of Archaeology, p.100) The Australian Aborigines are the descendants of later immigration and are not descended from the earlier populations. On the world in general in regard to modern populations and ice age populations one source states. "Using present techniques, it seems difficult to ascertain reliable resemblance's between skulls older than 10-12 KY and modern regional specimens from the same or a related area." (The History and Geography of Human Genes, p.73) In other words, there has been a global population replacement as the result of the pleistocene extinction event having an impact on mankind, which considering the size of it's impact on the animal kingdom, shouldn't come as a surprise.Your very intelligent statement of, "In any case, all three hypotheses are full of holes currently which makes both research and debate rather interesting." is right on the money, my theory has it's holes as well, as you have pointed out, but I believe that with research those holes can be plugged. So far my findings of marine diatoms at an elevation of 1000 ft here in Wisconsin in the center of the North American continent shows that there was a very substantial marine transgression event at the end of the ice age when the extinctions are said to have occurred, it seems highly likely that it had a key role in those extinctions. It will take more very interesting research to measure the extent of the impact of this late ice age marine transgression on the Pleistocene extinctions. I suspect marine flooding will turn out to be the major cause.Wm Scott Anderson

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