Overkill, Overchill, Overill? Megafaunal extinction causes

Bacteria were not ruled out, but there are number of problems in searching for them from ancient materials not associated with viruses. For example, there are a lot of free living forms related to pathogenic forms so getting a funny bacterial sequence does not mean it is not a soil contaminant. Also, I could go outside, take some soil, prep DNA and sequence and find unknown species of bacteria. What do you do with an ancient sample where you find uknown bacteria when you cannot classify the modern ones? Also the dynamics of viral infections seemed more appropriate for a hypervirulent pathogen than a bacterial pathogen...It also depends on what tissues you can get.. With mammoths it is not so bad. Most is bone, but I have bone marrow, skin, brain, lung, heart, you name it from some samples....in any case, I can say so far nothing has worked ...it would probably help if I was not doing all of this a side project to a side project I have met with Paul Martin several times. He is a really nice guy and really smart...even when people disagree with him...his latest idea is to introduce elephants back into the wild in the U.S. since they were there before.

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But what can't be eaten can be used for other quite useful purposes, from shelter to clothing.

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Where are the remains of this shelter and clothing considering how many other things are preserved in the same environments?

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I find it surprising that you would expect to find even a significant percentage of total kill sites from a species hunted in such a vast range for such a (geologically) insignificant time. We don't hold anywhere close to such a standard for other fossils - why would we expect it for mammoths? A much more reasonable stance would be to compare the number of mamoth fossils found at kill sites during this time period to those not found at kill sites.

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There are thousands upon thousands of mammoth fossils found everywhere from Europe to Mexico and yet only a few agreed upon kill sites. Evidence of human settlement such as Clovis suggest there were not a whole hell of a lot of people around so each person would have to kill a lot of megafauna to make any dent in the population much less provoke extinction. Why are there so few kill sites?

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Why? Because of the size? If so, then Mylodon isn't addressed.

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I was being a bit ironic here since eating a sloth sounds disgusting. Mylodon had ossicles throughout its skin and had, like mammoths a low fat to muscle ratio...not really idea for subsistence.

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Humans are inventive. Depending on species, you may find mammoths that were upwards of 10 tons. Mylodon was only the size of an ox. Yes, it's better armored - but so? Humans have fought off far more fearsome armored creatures than that - for example, Megalania prisca. Throughout history, humans have killed crocodiles and alligators; small families of islanders alone have fought off komodo dragons, which have some pretty impressive armor; etc. I have little doubt that humans could have killed mylodon. Our chiefest hunting ability has been to learn the weak points of our prey.

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We are not talking hunting. We are talking hunting to extinction..every last member of the species gone. Why is it that the humans prior to the end Pleistocene were so much more inventive that they decimated the megafauna and then almost NO subsequent megafaunal extinctions occurred in the ensuing 10,000 years?

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I find it amazing that many people have trouble accepting that, given the track record of humans, that this would happen to the megafauna. What we're dealing with is a "land of plenty" situation. Humans move into an area where animals are not adapted to survive with humans hunting them or competing for their food supply, and where the flora is in rough equilibrium with its environment. Humans encounter what seems like a limitless hunting and harvesting paradise. A human population explosion occurs, and a native species population bust occurs, with some species going extinct. It has happened across the entire planet. If too many species go extinct in a region, the human populations there will decline or die out as well. As a consequence, over time the more balanced resource-utilizing societies are selected for.

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I am more surprised that people immediately assume that all cultures will be completely wasteful and destructive...even without evidence. The population boom does not have evidence. There is also little evidence that the end Pleistocene environment was in equilibrium. Dramatic climatic changes were occuring. There would have been no humans even there if the climate changes had not occurred. Hunter gatherer societies rely much more on the females gathering than the supplemental protein the hunters bring in. Why are African megafauna, which are hunted and have been for even longer by humans, not extinct? Elephants numbered in the millions in Africa, why were they not "the land of plenty" leading to full scale Rambo attacks to decimate them and lead to a human population explosion? I find overkill a poor explanation for the complete extinction of Pleistocene megafaunal species.

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And I agree with Speel-yi - there is far too wide of a range of species that go extinct to be explained by disease alone. I don't buy into the concept of a lethal disease that happens to jump species, but never made it over before we did, despite all of the migrations by other species of animals. Disease may be part, but wasn't the cause itself.

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There are a lot of viruses and bacteria that can jump among species and cause mass die offs. And all you have to do is nail a few keystone species like mammoths and that will cause problems for everyone else. And megafauna would be very suceptible since their gestation times are so long. Kill all the baby elephants quickly, it will take two years before the next round are born. If the adults are sick it will take longer if at all. And I never said it was a singular cause...a hypothetical important one where we have a chance (in theory) to gather evidence at the molecular level but not a sole cause. Overkill has not produced almost any postive evidence. Climate change is still being worked on...it is still up in the air but I think overkill is the weakest.

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

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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.

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Hi wmscott,
Thanks for the post. I was afraid this thread might become extinct Let me address a few of the issues you brought up the best I can. The keystone species of interest, i.e. mammoths did not survive anywhere (except Wrangel Island) after about 9,000 years ago. I am interested in the animals that survived nowhere after the end Pleistocene. Humans are also not necessarily predicted to be the carrier of the bug (or bugs). However, as you point out, they would have to have co-evolved with the pathogens in order not to be suceptible. It is more like a typhoid Mary effect of humans, their commensals, whatever parasites they were bringing with them, laying waste to immunologically naive megafauna with slow population growth due to long gestation time being a huge disadvantage for them. Many pathogens do not leave any trace evidence such as deformities or scarring in bone. A few do and there is a group trying to isolate Mycobacterium from bovid fossils. As to DNA testing of fossils, outside of the group I worked for a few years ago, nobody else was doing it...so there were two people (me and my tech) working on substandard materials for two years on a hypothesis that was proposed in 1996. I know it is a bit of a lame excuse, but the number of people going after pathogens relative to those studying climate and overkill makes it a bit premature to write off the chance of gathering supporting evidence.

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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.

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However, why was climate change (from everything I have heard) asynchronous throughout that period yet extinctions simultaneous? Why would mammoths in Montana be wiped out by a flood but humans survived. Why did mammoths survive on Wrangel Island yet a stones throw away in Siberia they went down? Why did muskoxen and buffalo survive? A global flood should have affected African megafauna (or Indian-southeast Asian) but it did not (or at least not to the extent of the areas where humans and their commensals showed up). I think there are a lot of climate change flaws you may be overlooking.I like the climate work and think it is worthwhile because one can formulate testable hypotheses based on it (and it is itself testable and falsifiable ultimately). Overkill, which I am glad we agree on, is lacking evidence but even finding evidence that is reliable is a challenge since markings on a bone do not mean the animal was hunted by humans. As to overill, while I will fully admit that we were unable to generate positive molecular support, it was the result of a pilot study..and biomolecular-wise, my experiences with mammoth (and other extinct megafauna) is that between 0-30% of the best preserved samples have any DNA at all. So the challenge is immense but still warrants further work before writing off pathogens completely.cheers,
M

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Where are the remains of this shelter and clothing considering how many other things are preserved in the same environments?

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1) How much ancient clothing and shelter *has* been found? Hides don't preserve well over the aeons. Where do you think they lived, in ice caves? Native americans, when westerners encountered them, were living in shelters made of the hides of the large game that they hunted. Why would you expect otherwise from the Clovis people?2) It has been found clovis people used numerous bone tools (although their hunting tips were flint).The question is not how many kill sites. The question is the ratio of the number of mammoth fossils found at kill sites, to the ratio of fossils found elsewhere from during this brief time period. Kill sites are going to be small and isolated, making them harder to find. Also, kill sites will only reflect places where killing mammoths was related to geography.

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I was being a bit ironic here since eating a sloth sounds disgusting. Mylodon had ossicles throughout its skin and had, like mammoths a low fat to muscle ratio...not really idea for subsistence.

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And still would feed a person for an incredibly long time.

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We are not talking hunting. We are talking hunting to extinction..every last member of the species gone.

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In the case of the mammoth, I am not. This is now the third time I have had to say this. I believe that hunting was *one* factor, of many. Am I going to be made to state this yet again?

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Why is it that the humans prior to the end Pleistocene were so much more inventive that they decimated the megafauna and then almost NO subsequent megafaunal extinctions occurred in the ensuing 10,000 years?

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How many times to I have to state this as well? Please, Mammothus - for the last time: The cultures that destroyed all of the large game in their areas would themselves be selected against. It takes time for a steady state to be reached. If you have an argument against *this*, please state it, but don't make me repeat it yet again.

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I am more surprised that people immediately assume that all cultures will be completely wasteful and destructive...even without evidence.

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Care to address the Anasazi or the Easter Islanders? I can give you plenty more examples of native environment destruction if you'd like. Want some native animal extinctions which are obviously due to hunting? I can discuss Madagascar and New Zealand if you'd like.

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The population boom does not have evidence.

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Stephen Mithen, of the McDonald Institute for Archaeological Research in Cambridge has put the human population at 12 million before the mammoths fell significantly, and had an extinction at about 5,500 years after human arrival. Here's some info about his computer modelling:http://www.dreamwell.com/ali/anthro/mammoth.htmThey also discuss some critiques of the overkill theory - if you would like to bring them up, by all means do. Note that this is a simulation for the kill-only cause of extinction, which I do not agree with.

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There is also little evidence that the end Pleistocene environment was in equilibrium. Dramatic climatic changes were occuring.

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No - equilibrium with *humans*. Since humans and their effects were the chief cause of the extinction (directly and indirectly), and the climate is just one of many factors, it itself isn't that major - if equilibrium can be reached with humans.

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There would have been no humans even there if the climate changes had not occurred. Hunter gatherer societies rely much more on the females gathering than the supplemental protein the hunters bring in.

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Completely true - in societies that are in equilibrium, in temperate climates (the number that I've typically heard is 80% from gathering, 20% from hunting in such environments). If the society is focusing heavily on hunting for calories, it is not in equilibrium. If we're not talking about a temperate climate, then gathering isn't as major of a percentage of calories. How many calories did the innuits traditionally get from plants, for example?

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Why are African megafauna, which are hunted and have been for even longer by humans, not extinct? Elephants numbered in the millions in Africa, why were they not "the land of plenty" leading to full scale Rambo attacks to decimate them and lead to a human population explosion?

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For the last time: Because they are in equilibrium. Cultures that have hunted the species in their area to extinction have been selected against. The end result is society whose values and way of life reflects as much as they can take from the local environment without damaging it. Likewise, the animals themselves are more adapted to human predation, learning to instinctively fear this (relatively) light, unassuming creature.When europeans moved to the new world, they suddenly found passenger pigeons, in abundance. Europeans had not traditionally relied on them as a food source - they had a fairly sustainable system of agriculture, livestock, and limited game hunting. Suddenly, here is this plentiful food source. We hunted them to extinction. And largely not through technology - it was mostly done through trapping and bagging. Why should we believe that the continent's natives were somehow different when *they* arrived?

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There are a lot of viruses and bacteria that can jump among species and cause mass die offs.

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Name one that can jump between most large mammal species that is highly lethal. Just one. Yes, there are diseases that can jump species. There are diseases which are lethal. But one that can jump to such a broad range of species, and is lethal to all of them, is not evidenced by what we find in the world.

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And all you have to do is nail a few keystone species like mammoths and that will cause problems for everyone else. And megafauna would be very suceptible since their gestation times are so long. Kill all the baby elephants quickly, it will take two years before the next round are born. If the adults are sick it will take longer if at all.

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Exactly - that is why the cumulative effect of many types of change is so critical.

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And I never said it was a singular cause...

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You've certainly implied it.P.S. - clovis rambos - Google Search------------------
"Illuminant light,
illuminate me."

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Name one that can jump between most large mammal species that is highly lethal. Just one. Yes, there are diseases that can jump species. There are diseases which are lethal. But one that can jump to such a broad range of species, and is lethal to all of them, is not evidenced by what we find in the world.

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Why would we necessarily be talking about one disease? The land bridge that allowed us across would have also allowed other animals to cross. You've got the meeting of two viral and bacterial worlds.------------------
No webpage found at provided URL: www.hells-handmaiden.com

Ok. Then name a series of lethal diseases which can cover the wide variety of species that we see go extinct.It's just not feasable. We've seen plenty of hunting to extinction, and plenty of habitat-destruction-to-extinction, etc, but never before witnessed a disease-to-extinction, especially not across such a wide variety of species.------------------
"Illuminant light,
illuminate me."

Rei stated:

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Completely true - in societies that are in equilibrium, in temperate climates (the number that I've typically heard is 80% from gathering, 20% from hunting in such environments). If the society is focusing heavily on hunting for calories, it is not in equilibrium. If we're not talking about a temperate climate, then gathering isn't as major of a percentage of calories. How many calories did the innuits traditionally get from plants, for example?

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From Current Anthropology--Frank Marlowe, "Male Contribution to Diet and Female Reproductive Success among Foragers" Volume 42, Number 5, December 2001 pages 755-759:

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Variation in male contribution to diet. Male contribution to diet varies from 25 to 100%, with a mean of 64%...Because there is less edible plant food for women to gather in colder climates, male contribution is higher at higher latitudes, where effective temperature is lower.

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The difficulty with moving into a new territory is that you may not recognize food plants until many years have passed. You can recognize game animals quite easily.Then it should also be considered that when one game animal becomes scarce, you will switch to another prey that is more easily found and the unhunted species can recover in numbers. Humans are generalists when it comes to hunting, they do not rely on any one type of animal to meet their needs.Optimal Foraging Theory suggests that predators will simply go after the easiest prey available. In an environment where mammoths and bison were grazing side by side, the bison would quite easily be the animal of choice for most paleohunters. There is also some suggestion that hunting bison will actually increase their rate of reproduction. If this were to occur, they could outcompete the mammoths that they shared their habitat with. Prehistoric overgrazing might have selected against an animal that needed tall grass species to eat.Anyhow, that's my story and I'm sticking to it.------------------
Bringer of fire, trickster, teacher.[This message has been edited by Speel-yi, 10-17-2003]

Hi Rei,Although I concur that the hyperdisease hypothesis is not tremendously well-supported - there's no "smoking gun" - the reasoning you gave for rejecting it is not valid. It might surprise you to know that there are quite a few panzootic diseases that jump a wide variety of species. The one that springs immediately to mind is the Paramyxoviridae family morbillivirus that causes rinderpest. This pathogen effects cattle, sheep, goats, pigs, cape buffalo, giraffes, wildebeest, gazelle, kudu, hippos, etc. Basically anything with a cloven hoof (except camelids, for some reason). It has high mortality (80-90% depending on species) if untreated and the type of wildfire transmission rate postulated for the hyperdisease hypothesis. It is also a relatively fragile virus - meaning it burns out fairly quickly and can tolerate only a narrow range of temperature, etc. However, it has had significant impacts on populations wherever it is inadvertently introduced - from Indonesia (where it nearly wiped out the swayback pig population), to the Masai's domestic cattle herds of Kenya or the wildebeest of the Ngorogoro. Although the Pleistocene extinction was probably not rinderpest (after all, the buffalo survived), some type of similar pathogen is believed to be the cause.In any case, there is a wide variety of pathogens - including such non-viral factors like mites (e.g. Sarcoptes scabiei, which is threatening foxes in Sweden and wombats in Australia), or protozoans (e.g. the Plasmodium species that causes avian malaria), and fungus (e.g., Batrachochytrium dendrobatides that is causing global dieoffs in amphibian populations - everything from anurans to salamanders), etc - that quite easily not only jump between species, but between families and even classes. For a rather good discussion of the panzootic and epizootic threat, see Daszak P, Cunningham AA, Hyatt AD, 2000, "Emerging Infectious Diseases of Wildlife Threats to Biodiversity and Human Health", Science 287: 443-449. Actually, that's a bit misleading. We've seen widely dispersed populations of single species eliminated globally by disease (ex, the global extinction of the snail Partula turgida by the protozoan parasite Stenhausia), and we're currently seeing the global reduction of amphibians by the Batrachochytrium fungus. Also, I'd suspect in the absence of vaccine, even rinderpest could cause global extinctions of the widely variable hosts, assuming it could get from point A to point B on its own somehow. So it IS feasible that some pathogen accompanied humans and their critters across the land bridge, and either directly or after mutation was able to cause the Pleistocene dieoff. As to whether it actually occurred, well, there isn't a lot of evidence. As I noted in my previous post on this thread, I'm not sure it makes a great deal of difference, since the cascade effect would be the same, regardless of proximate cause.[This message has been edited by Quetzal, 10-17-2003]

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1) How much ancient clothing and shelter *has* been found? Hides don't preserve well over the aeons. Where do you think they lived, in ice caves? Native americans, when westerners encountered them, were living in shelters made of the hides of the large game that they hunted. Why would you expect otherwise from the Clovis people?

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Skins, bone huts, every different part of mammoths and various other extinct megafaunal species are found throughout Siberia in excellent preservation. Fairly intact skeletons of megafauna are found throughout North America. Why are all of the shelters etc then absent? You would expect a lot more than what is found if mammoths were being hunted so intensely.

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2) It has been found clovis people used numerous bone tools (although their hunting tips were flint).

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The question is not how many kill sites. The question is the ratio of the number of mammoth fossils found at kill sites, to the ratio of fossils found elsewhere from during this brief time period. Kill sites are going to be small and isolated, making them harder to find. Also, kill sites will only reflect places where killing mammoths was related to geography.

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If kill site are small and isolated how did overkill bring down a species that was spread from Europe to Mexico in about 1000 years by making pin pricks at the population by hunting?

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How many times to I have to state this as well? Please, Mammothus - for the last time: The cultures that destroyed all of the large game in their areas would themselves be selected against. It takes time for a steady state to be reached. If you have an argument against *this*, please state it, but don't make me repeat it yet again.

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Selected against how? They had muskoxen, bison, deer, caribou, moose (Sorry Moose ), bear, marine mammals all megafaunal and all in abundance that they could have turned and slaughtered. Why stop after the truly large megafauna was gone? I see no evidence of negative selection before, during or after the end Pleistocene.

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Care to address the Anasazi or the Easter Islanders? I can give you plenty more examples of native environment destruction if you'd like. Want some native animal extinctions which are obviously due to hunting? I can discuss Madagascar and New Zealand if you'd like.

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You can discuss anything you want. Island extinctions do not work exactly the same way as continental with species as widely distrubted as mammoths. And don't try to hang the idea on my that I dont believe humans cannot cause extinction. I just don't see that there is any support for humans being a singular cause or even an important cause of end Pleistocene megafaunal extinctions via overhunting. Even the evidence for moa extinctions as due to hunting pressure has come under fire recently. Island extinctions arentsuch an open and shut case. Even environmental destruction you are talking about does not explain the mass extinctions at the end Pleistocene.

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Stephen Mithen, of the McDonald Institute for Archaeological Research in Cambridge has put the human population at 12 million before the mammoths fell significantly, and had an extinction at about 5,500 years after human arrival. Here's some info about his computer modelling:

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http://www.dreamwell.com/ali/anthro/mammoth.htm

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They also discuss some critiques of the overkill theory - if you would like to bring them up, by all means do. Note that this is a simulation for the kill-only cause of extinction, which I do not agree with.

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Here are some more recent studiesProc Natl Acad Sci U S A. 2002 Nov 12;99(23):14624-7. Epub 2002 Nov 04. Related Articles, LinksExplaining the Pleistocene megafaunal extinctions: models, chronologies, and assumptions.Brook BW, Bowman DM.Key Centre for Tropical Wildlife Management, Northern Territory University, Darwin 0909, Australia. barry.brook@ntu.edu.auUnderstanding of the Pleistocene megafaunal extinctions has been advanced recently by the application of simulation models and new developments in geochronological dating. Together these have been used to posit a rapid demise of megafauna due to over-hunting by invading humans. However, we demonstrate that the results of these extinction models are highly sensitive to implicit assumptions concerning the degree of prey naivety to human hunters. In addition, we show that in Greater Australia, where the extinctions occurred well before the end of the last Ice Age (unlike the North American situation), estimates of the duration of coexistence between humans and megafauna remain imprecise. Contrary to recent claims, the existing data do not prove the "blitzkrieg" model of overkill.Here is a pro overkill paper by the most over the top human only guy there isScience. 2001 Jun 8;292(5523):1893-6. Related Articles, LinksErratum in:
Science 2001 Sep 21;293(5538):2205.Comment in:
Science. 2001 Nov 16;294(5546):1459-62.A multispecies overkill simulation of the end-Pleistocene megafaunal mass extinction.Alroy J.National Center for Ecological Analysis and Synthesis, University of California, 735 State Street, Suite 300, Santa Barbara, CA 93101, USA. alroy@nceas.ucsb.eduA computer simulation of North American end-Pleistocene human and large herbivore population dynamics correctly predicts the extinction or survival of 32 out of 41 prey species. Slow human population growth rates, random hunting, and low maximum hunting effort are assumed; additional parameters are based on published values. Predictions are close to observed values for overall extinction rates, human population densities, game consumption rates, and the temporal overlap of humans and extinct species. Results are robust to variation in unconstrained parameters. This fully mechanistic model accounts for megafaunal extinction without invoking climate change and secondary ecological effects.What part of the critique do you feel is important to the discussion?

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), and the climate is just one of many factors, it itself isn't that major

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You don't think climate is important for species adapted to specific vegetation and significantly colder (or at least stable) yearly temperature cycles? Considering how drastically the landscape changed as a result of the transition from Pleistocene to Holocene, I think climatic impact must have been a tremendous selection pressure on the entire ecosystem.

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Completely true - in societies that are in equilibrium, in temperate climates (the number that I've typically heard is 80% from gathering, 20% from hunting in such environments). If the society is focusing heavily on hunting for calories, it is not in equilibrium. If we're not talking about a temperate climate, then gathering isn't as major of a percentage of calories. How many calories did the innuits traditionally get from plants, for example?

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Why would you assume that even without equilibrium there would be a shift to something as unpredictable as hunting success from gathering where there is a much higher probability of obtaining calories for your group?

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For the last time: Because they are in equilibrium. Cultures that have hunted the species in their area to extinction have been selected against. The end result is society whose values and way of life reflects as much as they can take from the local environment without damaging it. Likewise, the animals themselves are more adapted to human predation, learning to instinctively fear this (relatively) light, unassuming creature.

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When europeans moved to the new world, they suddenly found passenger pigeons, in abundance. Europeans had not traditionally relied on them as a food source - they had a fairly sustainable system of agriculture, livestock, and limited game hunting. Suddenly, here is this plentiful food source. We hunted them to extinction. And largely not through technology - it was mostly done through trapping and bagging. Why should we believe that the continent's natives were somehow different when *they* arrived?

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What evidence is there that Africa was in equilibrium? There were population migrations in and out of the continent. The end Pleistocene climate transitions did not just pass Africa by. If there is negative selection for killing when things are scarce but it is positively selected as soon as there is " a land of plenty" then surely the selectively advantageous overkill would have returned to Africa as a behavior considering that elephant populations were dramatically larger than they are currently. Why would animals as intelligent as elephants be so slow to realize when something is dangerous? There is even counter evidence that shows that less intelligent animals than elephants can learn novel predator avoidance in a single generationScience. 2001 Feb 9;291(5506):1036-9. Related Articles, LinksComment in:
Science. 2001 Feb 9;291(5506):997-8.Recolonizing carnivores and naive prey: conservation lessons from Pleistocene extinctions.Berger J, Swenson JE, Persson IL.Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV 89512, USA. berger@unr.eduThe current extinction of many of Earth's large terrestrial carnivores has left some extant prey species lacking knowledge about contemporary predators, a situation roughly parallel to that 10,000 to 50,000 years ago, when naive animals first encountered colonizing human hunters. Along present-day carnivore recolonization fronts, brown (also called grizzly) bears killed predator-naive adult moose at disproportionately high rates in Scandinavia, and moose mothers who lost juveniles to recolonizing wolves in North America's Yellowstone region developed hypersensitivity to wolf howls. Although prey that had been unfamiliar with dangerous predators for as few as 50 to 130 years were highly vulnerable to initial encounters, behavioral adjustments to reduce predation transpired within a single generation. The fact that at least one prey species quickly learns to be wary of restored carnivores should negate fears about localized prey extinction.Why should I believe that all Pleistocen megafauna were somehow less adaptable in their behavior, that the selection pressure for overkill only works in one direction, that human cultures that did not practice overkill show up in the new world and start but those in Africa without any negative selection against intensively hunting megafuana do not? That in Asia and North America humans killed off mammoths and dozens of other large mammals but then their was intense selection pressure to stop this behavior even though there was still megafauna present in abundance? And finally, where are all the kill sites? If one accepts a number of 12 million people (which is much higher than any number I have ever heard) killed off ALL the megafauna of the size of mammoths in a short period of time why do we not find hundreds of kill sites that date to this age?

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Name one that can jump between most large mammal species that is highly lethal. Just one. Yes, there are diseases that can jump species. There are diseases which are lethal. But one that can jump to such a broad range of species, and is lethal to all of them, is not evidenced by what we find in the world.

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Pollack JD. Related Articles, Links
Caspian seal die-off is caused by canine distemper virus.
Trends Microbiol. 2001 Mar;9(3):108.J Gen Virol. 2003 Sep;84(Pt 9):2285-92. Related Articles, LinksThe origin of the 1918 pandemic influenza virus: a continuing enigma.Reid AH, Taubenberger JK.Division of Molecular Pathology, Department of Cellular Pathology and Genetics, Armed Forces Institute of Pathology, 1413 Research Blvd, Building 101, Room 1057, Rockville, MD 20850-3125, USA.Influenza A virus is a major public health threat, killing more than 30,000 per year in the USA alone, sickening millions and inflicting substantial economic costs. Novel influenza virus strains emerge periodically to which humans have little immunity, resulting in devastating pandemics. The 1918 pandemic killed nearly 700,000 Americans and 40 million people worldwide. Pandemics in 1957 and 1968, while much less devastating than 1918, also caused tens of thousands of deaths in the USA. The influenza A virus is capable of enormous genetic variability, both by continuous, gradual mutation and by reassortment of gene segments between viruses. Both the 1957 and 1968 pandemic strains are thought to have originated as reassortants, in which one or both human-adapted viral surface proteins were replaced by proteins from avian influenza virus strains. Analyses of the surface proteins of the 1918 pandemic strain, however, suggest that this strain may have had a different origin. The haemagglutinin gene segment of the virus may have come directly from an avian source different from those currently circulating. Alternatively, the virus, or some of its gene segments, may have evolved in an intermediate host before emerging as a human pathogen. Determining whether pandemic influenza virus strains can emerge via different pathways will affect the scope and focus of surveillance and prevention efforts.It should be noted that at the time of the 1918 flu pandemic, millions of pigs died from the flu as well.here is flu able to jump from birds to ferretsJ Virol. 2002 May;76(9):4420-9. Related Articles, LinksPathogenesis of avian influenza A (H5N1) viruses in ferrets.Zitzow LA, Rowe T, Morken T, Shieh WJ, Zaki S, Katz JM.Influenza Branch, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.Highly pathogenic avian influenza A H5N1 viruses caused outbreaks of disease in domestic poultry and humans in Hong Kong in 1997. Direct transmission of the H5N1 viruses from birds to humans resulted in 18 documented cases of respiratory illness, including six deaths. Here we evaluated two of the avian H5N1 viruses isolated from humans for their ability to replicate and cause disease in outbred ferrets. A/Hong Kong/483/97 virus was isolated from a fatal case and was highly pathogenic in the BALB/c mouse model, whereas A/Hong Kong/486/97 virus was isolated from a case with mild illness and exhibited a low-pathogenicity phenotype in mice. Ferrets infected intranasally with 10(7) 50% egg infectious doses (EID(50)) of either H5N1 virus exhibited severe lethargy, fever, weight loss, transient lymphopenia, and replication in the upper and lower respiratory tract, as well as multiple systemic organs, including the brain. Gastrointestinal symptoms were seen in some animals. In contrast, weight loss and severe lethargy were not noted in ferrets infected with 10(7) EID(50) of two recent human H3N2 viruses, although these viruses were also isolated from the brains, but not other extrapulmonary organs, of infected animals. The results demonstrate that both H5N1 viruses were highly virulent in the outbred ferret model, unlike the differential pathogenicity documented in inbred BALB/c mice. We propose the ferret as an alternative model system for the study of these highly pathogenic avian viruses.and good old rabiesG Batteriol Virol Immunol. 1979 Jan-Jun;71(1-6):47-54. Related Articles, Links[Routes of spread of the current rabies epizoonosis in Europe][Article in Italian]Pugliese A, Croce F.The present report describes the spreading paths of the rabic epidemic that is rapidly reaching Italy from Central Europe. The epidemiologic situation of neighbouring countries is examined and the sanitary measures undertaken in Europe against epidemic are compared.

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You've certainly implied it.

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Close, but that ain' me He writes way better...remember I am a molecular biologist..not a paleo...More seriously, in terms of gathering evidence, it is effectively useless to say lots of things contributed everyroup tries to test for evidence supporting their hypothesis and eliminate as many variables as possible. I am sure the end Pleistocene extinctions had multiple causes like everything else in nature. We can either support or eliminate potential candidates by doing research. The overkill guys like Alroy don't want anyone to do the research and just accept overkill.

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

Thank you, Quetzal, I was not familiar with the morbillivirus. However, it is worth nothing that the virus has never established itself in North America or New Zealand. That doesn't mean that some other disease could have been the culrpit, but I would expect that we would see at least some New World reminant of whatever disease it was.The die-offs we have seen occur everywhere humans have arrived, right after humans have arrived. We're not just talking about ungulates here, we're talking everything from Megalania prisca (a giant monitor lizard in Australia) to the Moa in New Zealand and the Elephant Bird (the "Roc" of legend, extinct in the late 1600s), to the large New World mammalian dieouts (Artiodactyla, Perissodactyla, Carnivora, Rotentia, Xenarthra, you name it). Virtually every single time humans have arrived in a place with large animals, this has happened. The concept of a fatal mite or protozoan even affecting such a diverse population, and having followed every migration, in every time period, that humans have taken, really seems quite unreasonable.

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We've seen widely dispersed populations of single species eliminated globally by disease (ex, the global extinction of the snail Partula turgida by the protozoan parasite Stenhausia)

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Funny. I'd say that the biggest cause of the death of Partula turgida was the introduction of a florida snail, to control the population of an escaped African snail. Only the last 5 snails died of the Stenhausia, and that was in captivity - the species was all but extinct anyway. That's nothing at all like this situation Mammothus advocates.

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and we're currently seeing the global reduction of amphibians by the Batrachochytrium fungus

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But nothing close to extinction. Even threatened populations seem to be holding out ok against it.I'm not saying that it's impossible for a species to go extinct from a disease - but I think the species has to be in *severe* trouble already before this can happen. This does not describe the megafauna at all - they were very widespread, across all kinds of climates. Disease may have been a "finishing blow", or something that perhaps weakened their populations, but disease - or even disease and climate together - causing this? Doesn't seem likely.------------------
"Illuminant light,
illuminate me."[This message has been edited by Rei, 10-19-2003]

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Skins, bone huts, every different part of mammoths and various other extinct megafaunal species are found throughout Siberia in excellent preservation. Fairly intact skeletons of megafauna are found throughout North America. Why are all of the shelters etc then absent? You would expect a lot more than what is found if mammoths were being hunted so intensely.

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Some poor-condition mammoth skin has been found in permafrost, but for the most part, it is bones that remain. Especially large bones and tusks. I still find it incredibly odd that you're expecting to find intact shelters from the Clovis civilization. It's not like they built giant cities out of stone and brick (which themselves are hard enough to find). We're talking about bands of nomads living in tents. And, as I stated, bone tools *have* been found from Clovis peoples (want references?). but most are in poor states of preservation.

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2) It has been found clovis people used numerous bone tools (although their hunting tips were flint).

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The question is not how many kill sites. The question is the ratio of the number of mammoth fossils found at kill sites, to the ratio of fossils found elsewhere from during this brief time period. Kill sites are going to be small and isolated, making them harder to find. Also, kill sites will only reflect places where killing mammoths was related to geography.

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If kill site are small and isolated how did overkill bring down a species that was spread from Europe to Mexico in about 1000 years by making pin pricks at the population by hunting?

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A single tribe makes pin pricks. Several million people cause a slaughter.

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Selected against how? They had muskoxen, bison, deer, caribou, moose (Sorry Moose ), bear, marine mammals all megafaunal and all in abundance that they could have turned and slaughtered. Why stop after the truly large megafauna was gone? I see no evidence of negative selection before, during or after the end Pleistocene.

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And there you are assuming again - assuming that regions did *not* experience a killoff of whatever large game were available. Just because a species didn't go extinct doesn't mean that it wasn't heavily hunted, and killed off in specific regions. You know very well that populations of large animals, due to smaller numbers, are less stable and more prone to extinction.

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You can discuss anything you want. Island extinctions do not work exactly the same way as continental with species as widely distrubted as mammoths.

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Madagascar and New Zealand are no small islands. Madagascar is about the size of Arizona. New Zealand is about the size of Colorado. The Moas of New Zealand had a maximal weight of about 300kg, compared to up to 7000kg for a mammoth. They both were herbavores; most of New Zealand's plants seem to have adapted specifically to avoid being eaten by Moas. I can'd find population estimates for moas or mammoths, but given the size ratios, I would expect that the ratio of mammoths in North America to moas in New Zealand would at least be reasonably low, making the population of Moas almost as stable as that of Mammoths.

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And don't try to hang the idea on my that I dont believe humans cannot cause extinction. I just don't see that there is any support for humans being a singular cause or even an important cause of end Pleistocene megafaunal extinctions via overhunting. Even the evidence for moa extinctions as due to hunting pressure has come under fire recently.

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Such as...?

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Island extinctions arent such an open and shut case. Even environmental destruction you are talking about does not explain the mass extinctions at the end Pleistocene

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The environmental example shows how drastically environmentally destructive early native tribes can be. Easter islanders *completely deforested* their island - do you realize what that would do to all species there? The Anasazi turned an area 80 kilometers in radius into a desert. These are not ecologically friendly people. As a result, what happened to them? The easter islanders decimated their populations. The Anasazi effectively dissapeared.In short, they were selected against.

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Here are some more recent studies

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What was that? You cited one study for, and one against, and simply declared that the one against was by an "over the top" guy, despite his very pessimistic assumptions. In case you're not aware, this is a hotly debated issue in the scientific community. What sort of studies did you expect to find?

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You don't think climate is important for species adapted to specific vegetation and significantly colder (or at least stable) yearly temperature cycles? Considering how drastically the landscape changed as a result of the transition from Pleistocene to Holocene, I think climatic impact must have been a tremendous selection pressure on the entire ecosystem.

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The dieouts at the end of the last ice age dwarf those of any other recent ice age. Normally, species have time to adapt due to the selective pressures of changing climate and vegetation, because the process is slow enough. Not in this case.

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Why would you assume that even without equilibrium there would be a shift to something as unpredictable as hunting success from gathering where there is a much higher probability of obtaining calories for your group?

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Unpredictable as hunting success in the arctic? What else do you expect people to survive on in the arctic, lichens or grasses? Even in temperate climates, what do you expect - gathering unknown plants from an unknown region, when there is large prey that has never learned to fear or avoid humans, that can feed a tribe for weeks?

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What evidence is there that Africa was in equilibrium? There were population migrations in and out of the continent. The end Pleistocene climate transitions did not just pass Africa by.

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Not climatic equilibrium - equilibrium with humans, the critical selection factor involved here. Equilibrium with humans involves both the humans having been selected not to overhunt their area, and the animals having adapted to avoid humans.

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If there is negative selection for killing when things are scarce but it is positively selected as soon as there is " a land of plenty" then surely the selectively advantageous overkill would have returned to Africa as a behavior considering that elephant populations were dramatically larger than they are currently.

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Then they are currently, or then they are before the introduction of guns and the ivory trade? BTW, up and down cycles are expected, but I would just like to clarify this point.

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Why would animals as intelligent as elephants be so slow to realize when something is dangerous?

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It's a sharp learning curve. Literally. It's not just the intelligence of the prey that matters. Equally critical are things like the difficult-to-change societal structure elements of the animal (unknown for mammoths), the time for knowlege of dangerous situations to fixate into the population as a whole instead of just a small group, and most critically the memes of the human societies involved not to overhunt.

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Why should I believe that all Pleistocen megafauna were somehow less adaptable in their behavior, that the selection pressure for overkill only works in one direction, that human cultures that did not practice overkill show up in the new world and start but those in Africa without any negative selection against intensively hunting megafuana do not?

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Humans developed during most of their evolution in Africa. There was plenty of time for adaptation both by humans, human culture, and the prey.

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That in Asia and North America humans killed off mammoths and dozens of other large mammals but then their was intense selection pressure to stop this behavior even though there was still megafauna present in abundance?

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Time. It takes time for equilibrium to be reached. There was no magical moment when humans just decided, "Hey! We should stop killing all the animals and altering the environment! We should adopt practicies and social expectations that control our population, instead of reproducing extensively as we have at the rate that filled up this continent".Once again, and hopefully for the last time: Large animals have smaller numbers, and consequently less stable populations.

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And finally, where are all the kill sites? If one accepts a number of 12 million people (which is much higher than any number I have ever heard) killed off ALL the megafauna of the size of mammoths in a short period of time why do we not find hundreds of kill sites that date to this age?

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1) If you want to dig a couple dozen feet down through layers of permafrost or other barriers, across 16,245,000 square miles, be my guest. Talk about unreasonable expectations... 2) For the last time, I do NOT claim that humans killed off all of the megafauna! I am an advocate of the theory that there are multiple causes, of which hunting is just one.

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Direct transmission of the H5N1 viruses from birds to humans resulted in 18 documented cases of respiratory illness, including six deaths

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Influenza, a species threatening disease? Rabies? Please.
Read my response to Quetzal on this front.

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The overkill guys like Alroy don't want anyone to do the research and just accept overkill.

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Yes, no evidence, except for the fact that we've witnessed it occuring with hundreds of species in modern times, and can look to the recent geological record for where it clearly has happened to many others in recent history.------------------
"Illuminant light,
illuminate me."[This message has been edited by Rei, 10-19-2003]

As I stated, I don’t support the hyperdisease model. Why are you insisting that anyone who doesn’t directly support overkill is by definition supporting hyperdisease in this thread? My point was that your disagreement with hyperdisease was based on invalid criticisms. There are a number of quite good arguments against and/or weaknesses in the model. Briefly:1. There are no known pathogens which can propagate through dozens of different species in a continental metapopulation (emphasis on continental). It would require a highly variable organism — one capable not only of an extreme rate of infection (AR~1.0), but also an extremely high mortality (MR~1.0) with an aerosol transmission and high mutability. The only current pathogen that comes close is rinderpest. No one is suggesting that rinderpest is the culprit in this case — it was an example of a pathogen that countered your assertion that no such pathogen exists, and its propagation through multiple species, decimating the effected populations in a wave front from initial point of introduction throughout West Africa is a reasonable model for the hyperdisease idea. Your argument, that rinderpest hasn’t been established in NA or New Zealand is specious — IOW, so what?2. Again relating to the nature of the pathogen, the existence of a highly virulent/high mortality bug implies that there is an intermediate host that provides a reservoir (i.e., that the pathogen doesn’t effect, or at least doesn’t kill). This would be required because of the rapid burn-out of this type of infection (wildfire effect). Something has to be wandering around re-introducing the bug. It has not been demonstrated that human specific-diseases of this virulence can be transmitted wholesale to multiple other species — it’s usually the reverse, making the suggestion that humans or their commensuals were the reservoir problematic.3. In a continental biosphere, the disease would have to depress/disrupt populations of species so rapidly that they have no possibility of recovery anywhere in their original range. In the case of the Late Pleistocene event, even in areas which were unsuitable for human habitation, isolated or relictual populations were ALSO decimated. IOW, the humans-as-infectious-reservoir may not have been able to reach them. Something would have survived — if not mammoth, then any one of the other large herbivores OR one of the generalist carnivores (smilodon might have had a problem, but what about Arctodus or Canis dirus?). When climate change occurs, populations don’t just habitat track latitudinally, they also track altitudinally (Rappaport’s Rule). Your pine forest is shifting north? No problem, you either go north, or you can go up and keep a very similar niche open. Of course, this argument goes doubly for the overkill idea.In my opinion, the overkill hypothesis is even weaker, if that’s possible. Not only do you have point three to contend with, you have the limitations imposed by technology and space. I’m sorry, but no matter effectively a group of humans managed to extirpate multiple species in the constrained space of an island using primitive, essentially hand tools (and there’s little question that the Maori accomplished that feat in a couple of centuries on New Zealand), you cannot logically extrapolate from that to a continent. Although it’s pretty fruitless to speculate on effective population size in a large migratory species like Mamuthus primogenus, overall we’re talking about (on two continents) at a minimum 10^7 to 10^9 individual animals eliminated in around 1-2000 years when you take all the different species into consideration. That’s a hell of a lot of killing. Unless the Clovis hunters were using automatic weapons and hunting from helicopters, it strikes me that the blitzkrieg hypothesis is asking more from human hunters than they are capable of. How many humans are we talking about? We’re looking at a front that is ever-expanding as these hunters moved further and further across the continent — IOW, their population density is getting smaller and smaller the further they travel into the continental landmass — the old force/space ratio dilemma faced by military planners. And they didn’t miss a single population? Please tell me how this was supposed to work.Worse, the overkill hypothesis ignores the fact that numerous species DIDN’T disappear that would be as easy or easier to kill than mammoths, for example. Why didn’t the American bison disappear? Too many of them? What about caribou, elk, mule deer, etc etc. These were harder to hunt than mammoth or ground sloth? And if they were, for some as-yet-to-be-identified behavioral quirk, where are all the bones? The few identified kill sites associated with Clovis archeologically are indistinguishable from any other cause of mass die-off — including hyperdisease. Those few undisputed tool-marked bones could just as easily have been worked AFTER death: Clovis-as-scavenger vice Clovis-as-hunter. None of the remains show undisputed evidence of hunting — which is not a negative in-and-of itself. They COULD have been killed by hunting. The marks are equivocal and don’t prove hunting.Finally, the correlation between the expanding human wave front and the last seen is unclear. Admittedly, this is due to the lack of fine grain in the fossil record, and holds for the hyperdisease as well as blitzkrieg hypotheses. What is clear is that first contact marked the beginning of the end. Whether humans were the ultimate or proximate causes remains to be determined. However, your belief that humans abruptly behaviorally adapted to a radically different lifestyle — in spite of the fact that there remained a wide variety of prey species they could have continued to massively over-exploit — requires even more assumptions than hyperdisease. After all, the pattern of the extinctions — massive numbers at first contact (some 40 genera) as nave species are effected by a new pathogen, followed by a lack of extinction after the surviving species become less susceptible — is as easily attributed to normal disease reaction as it is to over-hunting.Finally, some specific points from your reply: Depends on how you define it. The species was preserved in a lab as an effort to replenish it and save it from extinction. The species actually crashed from 260 individuals to zero in just under 21 months (1994-96). However, it was an counterexample to your assertion that no species had ever gone extinct through disease — not that this was a hyperdisease. Unfortunately, your assertion does not a rebuttal make. Your turn to provide references, as my sources contradict yours. Not only the Daszak et al, 2000 I cited above, but also specifically relating to the amphibians see Daszak, Berger L, Cunningham AA, Hyatt AD, Green DE, Speare R, 1999, Emerging Infectious Diseases and Amphibian Population Declines, Journal of Emerging Infectious Diseases, 5:735-748. This latter reference discusses not only global population decline as I noted, but specifically the extinction of Bufo periglenes, possible extinction of several other rainforest species not related to habitat destruction, and massive declines in other species. And your reference is?[This message has been edited by Quetzal, 10-20-2003]

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Some poor-condition mammoth skin has been found in permafrost, but for the most part, it is bones that remain. Especially large bones and tusks. I still find it incredibly odd that you're expecting to find intact shelters from the Clovis civilization. It's not like they built giant cities out of stone and brick (which themselves are hard enough to find). We're talking about bands of nomads living in tents. And, as I stated, bone tools *have* been found from Clovis peoples (want references?). but most are in poor states of preservation.

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Ok, so first you say small bands of nomads living in tents but then immediately below

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A single tribe makes pin pricks. Several million people cause a slaughter.

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So there is no evidence because the population was sparse and disperesed but there were so many millions of people simultaneously hunting mammoths that they caused their extinction? In addition you propose a hypothesis is valid because NO evidence is left behind? So I guess if 10,000 kill sites are found next week overkill will be invalidated?And sorry, while you are correct that most mammoths are represented by bone there are tons of skin samples and some almost fully preserved carcasses including Dima from which I have personally observed brain, liver, intestine, heart, blood, etc.

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And there you are assuming again - assuming that regions did *not* experience a killoff of whatever large game were available. Just because a species didn't go extinct doesn't mean that it wasn't heavily hunted, and killed off in specific regions. You know very well that populations of large animals, due to smaller numbers, are less stable and more prone to extinction.

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Then where is the huge genetic bottleneck in all of these species? Bovids, nope, equids nope, canids, nope...cervids, nope..muskoxen, sure though it is hard to determine if they had a bottleneck at all and some work I am doing right now suggests not.

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Madagascar and New Zealand are no small islands. Madagascar is about the size of Arizona. New Zealand is about the size of Colorado. The Moas of New Zealand had a maximal weight of about 300kg, compared to up to 7000kg for a mammoth. They both were herbavores; most of New Zealand's plants seem to have adapted specifically to avoid being eaten by Moas. I can'd find population estimates for moas or mammoths, but given the size ratios, I would expect that the ratio of mammoths in North America to moas in New Zealand would at least be reasonably low, making the population of Moas almost as stable as that of Mammoths.

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It is relatively small compared to the area from Europe to Mexico where every single last one of the largest megafauna became extinct.in any case here is a referenceECOLOGY
Sporormiella and the late Holocene extinctions in MadagascarDavid A. Burney * , Guy S. Robinson * and Lida Pigott Burney **Department of Biological Sciences, Fordham University, Bronx, NY 10458; and The Louis Calder Center Biological Station, Fordham University, P.O. Box K, Armonk, NY 10504Communicated by Henry T. Wright, University of Michigan, Ann Arbor, MI, July 24, 2003 (received for review January 25, 2003)Fossil spores of the dung fungus Sporormiella spp. in sediment cores from throughout Madagascar provide new information concerning megafaunal extinction and the introduction of livestock. Sporormiella percentages are very high in prehuman southwest Madagascar, but at the site with best stratigraphic resolution the spore declines sharply by 1,720 yr B.P. (radiocarbon years ago). Within a few centuries there is a concomitant rise in microscopic charcoal that probably represents human transformation of the local environment. Reduced megaherbivore biomass in wooded savannas may have resulted in increased plant biomass and more severe fires. Some now-extinct taxa persisted locally for a millennium or more after the inferred megafaunal decline. Sites in closed humid forests of northwest Madagascar and a montane ericoid formation of the central highlands show only low to moderate Sporormiella percentages before humans. A subsequent rise in spore concentrations, thought to be evidence for livestock proliferation, occurs earliest at Amparihibe in the northwest at 1,130 yr B.P.And in fact for moa extinctions habitat destruction is considered just as plausible as huntingHoldaway RN, Jacomb C. Related Articles, Links
Rapid extinction of the moas (Aves: Dinornithiformes): model, test, and implications.
Science. 2000 Mar 24;287(5461):2250-4.

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The environmental example shows how drastically environmentally destructive early native tribes can be. Easter islanders *completely deforested* their island - do you realize what that would do to all species there? The Anasazi turned an area 80 kilometers in radius into a desert. These are not ecologically friendly people. As a result, what happened to them? The easter islanders decimated their populations. The Anasazi effectively dissapeared.

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In short, they were selected against.

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Which shows how different an island is from continental populations.

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What was that? You cited one study for, and one against, and simply declared that the one against was by an "over the top" guy, despite his very pessimistic assumptions. In case you're not aware, this is a hotly debated issue in the scientific community. What sort of studies did you expect to find?

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Considering you have been writing as if I am a stupid fuck for even challenging the holy overkill hypothesis I figured I would demonstrate that not everybody is convinced and that an anonymous internet forum poster such as myself represent the only skeptics...

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The dieouts at the end of the last ice age dwarf those of any other recent ice age. Normally, species have time to adapt due to the selective pressures of changing climate and vegetation, because the process is slow enough. Not in this case.

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So the other cyclical changes since the Pliocene where humans were not involved but extinction did occur could not have involved climate change? And I don't know that the extinctions at the end of the last ice age dwarfed previous die offs...the curious aspect of the end Pleistocene die offs was that they so specifically involved megafauna.

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Unpredictable as hunting success in the arctic? What else do you expect people to survive on in the arctic, lichens or grasses? Even in temperate climates, what do you expect - gathering unknown plants from an unknown region, when there is large prey that has never learned to fear or avoid humans, that can feed a tribe for weeks?

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So all of Europe to Mexico, where most of the megafauna that went extinct was concentrated, was artic? If this was the case humans would never have spread anywhere. It was precisely this retreat of the arctic that allowed for the spread of humans and other animals into north America. Nothrotheriops in Arizona was not living in the arctic...and Mammuthus columbi was not either. The gatherers would still supply a more predictable supply of calories than the hunters...and if a single mammoth could supply the group for weeks, why would they kill every single one and all of the other megafauna (except for all the other megafauna that they left alone)..never prey switch either when the density of one species got to low to be worth it?

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Not climatic equilibrium - equilibrium with humans, the critical selection factor involved here. Equilibrium with humans involves both the humans having been selected not to overhunt their area, and the animals having adapted to avoid humans.

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What equilibrium with humans? At this time humans were mass migrating all over the place. You had bountiful megafauna in Africa. What possible selection against killing them all would be in Africa that did not exist outside of Africa?

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Then they are currently, or then they are before the introduction of guns and the ivory trade? BTW, up and down cycles are expected, but I would just like to clarify this point.

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So 10,000 years go by and then Europeans hunt elephants with guns and for the first time put the species under pressure....what is the evidence for up down cycles in elephants prior to this? It certainly does not show up in the genetic record to my knowledge...quite a bit of variation still is present suggesting a huge effective population size was present prior to the recent hunting pressureMol Ecol. 2002 Dec;11(12):2489-98. Related Articles, LinksPatterns of molecular genetic variation among African elephant populations.Comstock KE, Georgiadis N, Pecon-Slattery J, Roca AL, Ostrander EA, O'Brien SJ, Wasser SK.Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, D4-100, Seattle, WA 98109-1024, USA.The highly threatened African elephants have recently been subdivided into two species, Loxodonta africana (savannah or bush elephant) and L. cyclotis (forest elephant) based on morphological and molecular studies. A molecular genetic assessment of 16 microsatellite loci across 20 populations (189 individuals) affirms species level genetic differentiation and provides robust genotypic assessment of species affiliation. Savannah elephant populations show modest levels of phylogeographic subdivision based on composite microsatellite genotype, an indication of recent population isolation and restricted gene flow between locales. The savannah elephants show significantly lower genetic diversity than forest elephants, probably reflecting a founder effect in the recent history of the savannah species.

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It's a sharp learning curve. Literally. It's not just the intelligence of the prey that matters. Equally critical are things like the difficult-to-change societal structure elements of the animal (unknown for mammoths), the time for knowlege of dangerous situations to fixate into the population as a whole instead of just a small group, and most critically the memes of the human societies involved not to overhunt.

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Interesting then that moose (the only animals tested thus far) learned in one generation to avoid predators. And there still is not clarification as to what the selective pressure was against overhunting considering buffalo and cervids (smaller ones) were expanding in population size as mammoths and other giant grazers were disappearing.

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Humans developed during most of their evolution in Africa. There was plenty of time for adaptation both by humans, human culture, and the prey.

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For some of their prey. But humans (if you don't accept multiregionalism) evolved in a single part of Africa and spread...why didnt they overkill as they spread out? Elephas maximus in India should have been wiped out. Land of plenty, no people, left Africa 4 million years before, did not co-evolve with humans...yet no overkill.

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Time. It takes time for equilibrium to be reached. There was no magical moment when humans just decided, "Hey! We should stop killing all the animals and altering the environment! We should adopt practicies and social expectations that control our population, instead of reproducing extensively as we have at the rate that filled up this continent".

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But that is what would have to be believed to accept overkill since they left lots of megafauna alone that were still in abundance. Human populations would be expected to exhibit behaviors conducive to their survival. Hunting a food source to extinction is not particularly compelling. Especially as the prey source declined and it takes more energy to find let alone kill the prey, there would be intense pressure to switch prey. As we see from elephant seals, if you leave a species alone even for a short while they recover..it is not easy to drive things to extinction....what would have been the selected behavior to hunt every single last mammoth down instead of turning and slaughtering all the buffalo which they did not.

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Once again, and hopefully for the last time: Large animals have smaller numbers, and consequently less stable populations.

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Oh really? And what is the evidence for this? elphants can reach tremendous population densities. So can other large herbivores...smaller populations than rats? Maybe, but small populations? the evidence runs against that.

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1) If you want to dig a couple dozen feet down through layers of permafrost or other barriers, across 16,245,000 square miles, be my guest. Talk about unreasonable expectations...

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Should not have to, most of the late mammoth finds are in areas that are not permafrost so the kill sites should be easy to stumble over.

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2) For the last time, I do NOT claim that humans killed off all of the megafauna! I am an advocate of the theory that there are multiple causes, of which hunting is just one.

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Except you have made clear you discount anything related to climate or pathogens as factors...in your response to Quetzal

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Disease may have been a "finishing blow", or something that perhaps weakened their populations, but disease - or even disease and climate together - causing this? Doesn't seem likely.

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Alroy also thinks we should not even start hunting around for pathogens since obviously it had to be overkill disregarding the complete lack of evidence. And you seem to be indicating that finding supporting evidence for overkill in the form of kill sites would be detrimental to the hypothesis?I am not wedded to any particular hypothesis...but just like creationism, I am not going to accept things merely because someone tells me they are right. I want evidence..especially if I am going to be addressed like a stupid ass. If the overkill guys come up with a ton of rock solid evidence and I am convince..great...then I have one less project to worry about. If the climate guys can fill in all the holes and contradictions in their hypothesis..ditto. If I cannot find any pathogens or find data exactly contradicting the overill hypothesis, then it is history. But at this point I think overkill is just as badly supported as overill.

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Influenza, a species threatening disease? Rabies? Please.
Read my response to Quetzal on this front.

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Depends, if you are immunologically naive and the population densities are as low as you have been claiming all you have to do is kill off the young (which are more suceptible anyway) and in a generation the population has collapsed. Even mild viruses can have a huge impact on megafauna for example elephant herpes of Loxodonta is often fatal to Elephas. The two genera can no longer be housed together (if you want a successful breeding program or dont want to blow the zoo budget on gancylovir).

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Yes, no evidence, except for the fact that we've witnessed it occuring with hundreds of species in modern times, and can look to the recent geological record for where it clearly has happened to many others in recent history.

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We have had megafaunal extinctions on the scale of the end Pleistocene in the last 10 K years? Please present this data. It would be a Science paper at the very least and a discovery of the century.