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Are you deliberately being like this? You know very well that 12 million people scattered across over 16 million square miles is under one person per square mile - i.e., scattered bands.
Deliberately being like what? You are arguing polar opposites. You first argue that there are so many people around at this point in history that they can hunt down every last breeding pair of mammoths and multiple other species of megafauna yet are so sparsely distributed "scattered bands", that no evidence could possibley exist that they killed ALL of these megafaunal species. Either the density was high enough for them to hunt the megafauna to extinction in which case one would expect to see evidence of such pervasive hunting or the density was much lower which provides no logical way that so few people would have killed off so many animals in so short a time.
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My god, Mammuthus, this is annoying. Please, if you're going to keep indirectly asserting that you would *expect* to find even a measurable percentage of the kill sites in 16 million square miles of land, then please explain why, or stop asserting it.
Hmmm, overill is critcized because of lack of evidence for what you and others "expect" to find yet I am not allowed to ask for evidence of mass hunting? I suppose then that because of lack of evidence for 12 million human inhabitants in North America at the end Pleistocene that this is good evidence that they were there? Don't you see that you are supporting a hypothesis that only thrives on LACK of evidence. You keep repeating this and then are defensive about the fact that there is virtually NO evidence for the scenario.
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Point to where even elephant kill sites from 100 years ago are found in Africa. We know that elephants were heavily hunted in Africa 100 years ago. Where are the sites? Kill sites typically preserve rather poorly, because they are not buried quickly, as a general rule. Gary Haynes (an archeologist who has studied modern elephants, and elephants in the fossil record) discussed how between 1984 and 1986 he saw 9,000 elephants culled, and has been unable to find any of their bones anymore. In reference to Clovis, "In fact, 15 sites with 50 mammoths dead in them to me is an extremely rich, enormously rich, archaeological record, of something going on over a very brief period."
15 sites with 50 mammoths and this is the sum total evidence that 12 million people inhabited North America and caused the extinction of the megafauna at the end Pleistocene. Do you really find this compelling? Case closed, Alroy can send us all home? Would you accept such tenuous support if it were a hypothesis you did not like? The culled elephants in Haynes studies were also collected for their ivory as Haynes notably leaves out of his comparison
Haynes first "Clovis mammoth sites are supposed to be rare. I think we can refute that pretty easily. I think Paul Martin originally, in his talk here, said something about something that I've told him, that there have been thousands and thousands of elephants killed -- not only in clearing of land for agricultural use, but in culling operations. In 1984, '85 and '86 I saw 9,000 elephants culled, and I cannot find a single site anymore of their bones -- within 10 to 15 years they're all gone. And I saw this happening within three months of every year, over those three-year periods."...but then
"Now, let me go to my Zimbabwe work, to my own fieldwork, because that's the viewpoint I can tell you the best, or the most about. Most of what I have produced seems to be used to support the climate-change-only model of explaining extinction. Now, admittedly, a lot of it actually does point that way very clearly. For example, if you look at the mammoth sites in the fossil record, and you look at modern elephant sites -- the ones that have been documented during culling or other noncultural death events -- they look very much alike. The same kinds of age profiles are represented in the fossil and the modern elephants; the same kind of geomorphic locations -- not at big rivers or big waterholes, or whatever -- these are at headwater locations, rather small streams.
There's lots of different species represented -- it's not only elephant or mammoth. There's large masses of bone; there's bone that looks like it could be broken artifactually, or broken to make something out of. And another point that oftentimes is not raised when comparing the modern elephant population depletion during the ivory-hunting craze of 100 years ago is that, in spite of the fact that many elephant populations were driven to about zero -- at least to a virtual zero point -- during the ivory-hunting phase of late 19th century southern Africa, they've recovered to some of the highest densities anywhere in Africa within a hundred years. So elephants can recover from overhunting. How could Clovis people, with spear points, have hunted an entire population of mammoths in North America to extinction, if people with high-powered rifles couldn't do it in the late 19th century?"
So, ivory collectors would have just left these culled elephants alone? They just dump the culled bones, don't burn them? How is this similar to what Clovis would use the bones for i.e. in Siberia you can find huts constructed from mammoth bones, why not in North America where all of these Rambo killers should have been building skyscrapers with the excess of bone they would have had available? And note, you are now switching from the immense use the mammoth carcasses would have to Clovis people to they just killed the mammoths and dumped them for fun so that all evidence for them conveniently disappeared.
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My claim was that bones are a lot more common than skin, and that what skin remains is typically in poor preservation. Do you have a specific counter to this assertion? I'm sure you're quite familiar with the big dissapointment that was Zharkov.
Which part of Jarkov do you mean? The skin I have in my freezer or the bone marrow? Or the disappoitment that it was not a grown version of Dima? Jarkov was badly overhyped. The Pilot site mammoth and the ones that are not reported except to museums are much more interesting not to mention well preserved.
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Nice assertion. Do you have anything to back it up with, or is it pure conjecture? The work that you're doing "suggests not"? Can you give an example?
What assertion? I asked you to give an example and you claim it is my assertion..nice evasion there Mr. Williams
Lets see..bovids..no obvious bottlenecks
Immunogenetics. 1997;46(3):237-44. Related Articles, Links
Analysis of genetic diversity at the DQA loci in African cattle: evidence for a BoLA-DQA3 locus.
Ballingall KT, Luyai A, McKeever DJ.
International Livestock Research Institute (ILRI), Box 30709, Nairobi, Kenya.
We describe the development of a polymerase chain reaction (PCR)-based approach for analysis of genetic diversity at the DQA loci in African Bos indicus and Bos taurus cattle. This approach, equally effective in European and Asian cattle breeds, detects the presence or absence of DQA1 and most duplicated DQA2 genes. Nucleotide and predicted amino acid sequence analysis of the highly polymorphic second exons, in addition to analysis of the locus-specific and relatively non-polymorphic transmembrane, cytoplasmic, and 3-prime untranslated regions, has provided evidence for considerable diversity between each of the duplicated DQA2 genes. Therefore, we propose the designation BoLA-DQA3 for the previously unpublished alleles at the second DQA2 locus. Fourteen distinct PCR restriction fragment length polymorphism (RFLP) patterns, each identifying families of alleles at three DQA loci, can be distinguished. Nucleotide sequence analysis of new PCR-RFLP patterns from 193 Kenyan Boran, Ethiopian Arsi (B. indicus), and Guinean N'Dama (B. taurus) cattle identified 13 DQA1 alleles within eight major allelic families, five DQA2 alleles within a single allelic family, and seven DQA3 alleles within three major allelic families.
not in horses either
Science. 2001 Jan 19;291(5503):474-7. Related Articles, Links
Comment in:
Science. 2001 Apr 13;292(5515):218-9.
Science. 2001 Jan 19;291(5503):412.
Widespread origins of domestic horse lineages.
Vila C, Leonard JA, Gotherstrom A, Marklund S, Sandberg K, Liden K, Wayne RK, Ellegren H.
Department of Evolutionary Biology, Uppsala University, Norbyvagen 18D, S-75236 Uppsala, Sweden. carles.vila@ebc.uu.se
Domestication entails control of wild species and is generally regarded as a complex process confined to a restricted area and culture. Previous DNA sequence analyses of several domestic species have suggested only a limited number of origination events. We analyzed mitochondrial DNA (mtDNA) control region sequences of 191 domestic horses and found a high diversity of matrilines. Sequence analysis of equids from archaeological sites and late Pleistocene deposits showed that this diversity was not due to an accelerated mutation rate or an ancient domestication event. Consequently, high mtDNA sequence diversity of horses implies an unprecedented and widespread integration of matrilines and an extensive utilization and taming of wild horses. However, genetic variation at nuclear markers is partitioned among horse breeds and may reflect sex-biased dispersal and breeding.
moose did have a bottleneck but in eurasia and at the wrong time..
Genetika. 2002 Aug;38(8):1125-32. Related Articles, Links
[Genetic diversity of moose (Alces alces L.) in Eurasia]
[Article in Russian]
Udina IG, Danilkin AA, Boeskorov GG.
N. I. Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, 119991 Russia. udi@vigg.ru
Polymorphism of nucleotide sequence of D-loop fragment of the mitochondrial DNA was studied in 20 moose from several local populations on the territory of Eurasia. Three main haplotype variants of D-loop were detected by molecular phylogenetic method, which formed three clusters named European, Asian and American. Intraspecies variation in the length of HVSI of D-loop of the mitochondrial DNA of moose was revealed. In the Far Eastern and Yakutian moose, haplotypes with a 75-bp deletion were found, which were most similar with haplotypes (also with the deletion), earlier observed in North American moose [1]. The highest diversity of the haplotypes of mitochondrial DNA is characteristic of Yakutia and the Far East (where three haplotype variants were found), which demonstrates the probable role of the region as the center of the species or as the region of ancient population mixture. The geographic region might be considered as a probable source of ancient moose migrations from Asia to America, basing on the data of distribution of mitochondrial haplotypes of D-loop and alleles of MhcAlal-DRB1. Divergence of nucleotide sequences of haplotypes with the 75-bp deletion (forming the American cluster on the phylogenetic tree) was the lowest (0.4%), which evidences respectively recent origin of the group of haplotypes. In Europe, only haplotypes of mitochondrial DNA referred to European variant were observed. Basing on analysis of variation of nucleotide sequences of D-loop, exon 4 of kappa-Casein and exon 2 of MhcALal-DRB1, we demonstrated that Eurasian moose studied belong to the unique species, which has probably passed through a bottle neck. The time of the origin of modern diversity of D-loop haplotypes of the species was estimated as 0.075-0.15 Myr ago.
canids either
J Hered. 1999 Jan-Feb;90(1):71-7. Related Articles, Links
Phylogenetic relationships, evolution, and genetic diversity of the domestic dog.
Vila C, Maldonado JE, Wayne RK.
Department of Biology, University of California, Los Angeles, USA. Carles.Vila@bmc.uu.se
The spectacular diversity in size, conformation, and pelage that characterizes the domestic dog reflects not only the intensity of artificial selection but ultimately the genetic variability of founding populations. Here we review past molecular genetic data that are relevant to understanding the origin and phylogenetic relationships of the dog. DNA-DNA hybridization data show that the dog family Canidae diverged about 50 million years ago from other carnivore families. In contrast, the extant canids are very closely related and diverged from a common ancestor about 10 million years ago. The evidence supporting a close relationship of dogs with gray wolves is overwhelming. However, dogs are remarkably diverse in mitochondrial and nuclear genes. Mitochondrial DNA analysis suggests a more ancient origin of dogs than has been indicated by the fossil record. In addition, dogs have originated from or interbred with wolves throughout their history at different times and different places. We test the possibility of an independent domestication event in North America by analysis of mtDNA variation in the Xoloitzcuintli. This unusual breed is believed to have been kept isolated for thousands of years and may be one of the most ancient breeds in North America. Our results do not support a New World domestication of dogs nor a close association of the Xoloitzcuintli with other hair-less breeds of dogs. Despite their phenotypic uniformity, the Xoloitzcuintli has a surprisingly high level of mtDNA sequence variation. Other breeds are also genetically diverse, suggesting that dog breeds were often founded with a large number of dogs from outbred populations.
My muskoxen data is not yet published so I am not putting it here.
I can go on and on with this but can you provide a clear cut example of ALL surviving megafauna going through a genetic bottleneck? If not, why did the hunters leave such a bounty alone? Your assertion is they were also attacking the other megafauna...can you back it up?
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And as I pointed out and you didn't address, Moas are about 1/23rd of the size of the Mammoths, and so would be expected to be much more stable in smaller populations.
Any reference for this?
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Whoah, look what we have here! Habitat destruction, hunting, and other mixed causes - of which hunting is one of them. Exactly what I have suggested this entire time.
Are you familiar with the quite common cooking sites filled with butchered Moa bones? Holdaway and Jacomb's population study paper which shows that from hunting alone a population of 158,000 moas (in an area the size of Arizona) would be dead within 160 years? Any of this? Here's a quick summary article:
Archaeology - Archaeology Magazine
Now this is odd... I reference heavy environmental destruction by both an island tribe, and a continental tribe, and you respond with:
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Which shows how different an island is from continental populations.
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Please explain how you got this. Do you not know who the Anasazi were?
Easy, on an island where are the refugia? Do you really think comparing and island population is identical to continental? If so why is there an entire subdiscipline dealing with island extinctions?
Relevant Publications: MacPhee, R.D.E. and P.A. Marx. 1997. The 40,000-year plague: Humans, hyperdisease, and first-contact extinctions. Pp. 169-217. In: Natural Change and Human Impact in Madagascar, S. Goodman and B. Patterson (eds.). Washington, D.C.: Smithsonian Institution Press. MacPhee, R.D.E. and C.E. Flemming. Mammalian extinctions since AD 1500: A preliminary census. In: The Living Planet in Crisis, J.L. Cracraft and F. Grifo (eds.). New York: Columbia University Press, in press.
Extinction: Complexity of Assessing Risk
In discussing the extinction risk of nave prey species confronted by reintroduced predators (Science's Compass, 9 Feb., p. 997), J. L. Gittleman and M. E. Gompper say that, apparently because of diverse anthropogenic impacts, "a markedly higher proportion of ungulate species compared with other mammalian taxa have become extinct in the past 500 years."
Not so. Although the belief seems to be widespread that large mammals such as ungulates have suffered substantial losses during the modern era (that is, the last five centuries), the facts lead to a different conclusion. Of the ~90 well-corroborated extinctions that have occurred at the species level within Mammalia during the past 500 years (1), only five species (6%) are members of Ungulata, when the broadest available cladistic definition of this taxon is used (2): two Malagasy hippos (Hippopotamus madagascariensis and H. lemerlei, both extinct around 1500); a North Pacific sirenian (Hydrodamalis gigas, extinct by 1768); and two African bovids (Hippotragus leucophaeus, extinct by 1800, and Gazella rufina, extinct before 1894). Of these, the first three are reasonably regarded as "first contact" extinctions, although the role of human overhunting in forcing these losses is evident only in the case of the sirenian. There is no meaningful evidence regarding the cause of loss of the two African bovids (1).
Getting the numbers right is important because extinction (loss of all members of a minimally diagnosable evolutionary unit) is a phenomenon in its own right, although it is often treated as merely the final stage of endangerment. Rating schemes, like the IUCN Red List, that attempt to assign extinction risk factors to endangered species are, of course, extremely important as possible guides to the planet's biotic future. But history is also important, even if its lessons are slippery. For example, the nature and cause of end-Pleistocene extinctions in the continental New World, which Gittleman and Gompper cite for their probative value, are in fact still obscure. If human overhunting of behaviorally nave species were mostly to blame for these losses [amounting to 130 species by our count (1)], how is it that during the past 10,000 years, there have been only two mammalian species-level extinctions (a Mexican cottontail and the sea mink) in the continental Americas--despite significant habitat destruction, numerous exotic introductions, and severe persecution of many species throughout this period. This pattern suggests that we should be looking for other factors as well in first-contact extinctions (3). So who has suffered most among mammals in recent times More than 50% of all species-level losses in the past 500 years are rodents; the groups next most affected are insectivores (13%) and chiropters (bats) (10%). Mammals of large body size (>44 kilograms) account for ~12% of modern-era species losses across all taxa (1). In other words, modern-era mammalian losses have been overwhelmingly minifaunal rather than megafaunal. And they have been overwhelmingly insular: the world's islands have been much more severely affected by species-level extinctions in recent times than have any continental biotopes, including the world's rainforests. If these patterns continue, it is the small, the island-bound, and the least charismatic that will continue to suffer most.
So Islands and continents are not different? Why is island biodiversity different then..or is this a Syamsu arugment that there are no real differences among any group, species, etc.?
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Exactly what I have suggested this entire time.
Where have you been suggesting a mixed approach? You have been claiming that absence of evidence for overkill is not harmful to the hypothesis, that my having any expectations of evidence is ridiculous, you have only defended overkill as the singular cause and then merely handwave in a few references to multicausation at the end of your posts. Where have you supported environmental change having an impact? As I recall you were as dismissive of my refering to climate as you have been to anything else I have said.
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I do not mean to sound as if I am insulting your intelligence, Mammothus. However, there are things you need to address. You still haven't explained why you would expect to find all of the kill sites when the land area in discussion is over 16 million square miles.
Because you cannot have such a low population density AND wipe out all the megafauna and leave no trace. And what is the possible use of an untestable unfalsifiable hypothesis? If lack of evidence and presence of absence both support overkill then it is useless scientifically.
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You haven't explained how you get that the ratio of megafauna kill site fossils and megafauna fossils that otherwise show evidence of hunting, to other fossils during this same brief time period, suggests that hunting wasn't a major factor.
15 sites with 50 bones that cannot even be distinguished from scavaging? A kill site cannot even be confirmed. Why do the tens of thousands of mammoth finds (mostly dating around the relevant time period due to preservation constraints) show natural death causes and not hunting? The ratio you ask for is overwhelmingly against overkill.
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You've yet to address the ample evidence of massive environmental destruction by native peoples, continental and island. Etc. You can see why I would be insistant on getting answers on these things from you. My apologies if it sounds insulting.
Yet you have dismissed every question I ask of you as purely stupid. That is what is insulting. Not that you challenge them. In any case, is there evidence of continental wide environmental impacts in the relevant areas for extinction? Again, evidence for human populations is sparse in this time period. You yourself say they would have been very dispersed. So how would that support human environmental impacts causing such massive ecological trauma? I have yet to read anyone proposing this in the extincition literature for continents so I am wondering where you get your support for this scenario.
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Are you actually trying to claim that this is related to climate change?
I said prior to the end Pleistocene extinctions there was massive movement of animals between the continents and multiple mass extinction events. This was before humans even left Africa so how could they have been a proximate cause? Mammuthus colombi (not the woolly mammoth) entered North America about 1 million years ago. The extinctions subsequent to this could not have been human initiated. There have been mass extinctions without humans on the scene as Quetzal also pointed out. So what you are addressing is unclear.
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The sad thing is that Wooly Mammoths might have made it, if not for the discovery by humans of Wrangel Island about 6,000 years ago. As soon as humans find it, the mammoths dissapear.
And interesting that the little evidence for humans on Wrangel Island show they were a fishing culture...and in a place where mammoths are so well preserved that you can stumble over the bones in every river and they contain bone marrow and have skin, there is not a single butchered find.
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They arrived in the New World from the arctic - their culture must have had to be completely adapted to survival in such cold climates to survive - including getting most of their diet from hunting. When expanding further south, you seem to just expect them to suddenly change culture and start farming or whatnot (what do you propose they did for food after getting used to a mostly meat diet, in an area filled with abundant large game animals?)
No, I do not expect them to start farming. But then where would you get a number of 12 million? Is there a single nomadic purely hunting group that has ever reached a population size like this? Even in Africa? And the arctic they were adapted to is not like Nanook of the North. There is a short growing season where gathering would be possible. And hunting as a sole source of survival in the artic would never have allowed for population explosion.
Of course some of the controversial much older dated sites in the Americas for human habitation also screw this scenario up...but also take overill as a cause out as well.
Oh yes, and the origin of the humans that entered the new world is not thought to have been the arctic but may have been in several waves and as far south as Mongolia so it is completely unclear that it was arctic adapted nomads who colonized Beringia and North America.
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Are you familiar with the extinction of the passenger pigeon? Humans didn't kill every last passenger pigeon - not even close. However, once the population was damaged enough, it was unable to recover. People prey-switched on Moas, also, but they still went extinct. The archaeological evidence switches from butchered moas to other game and shellfish.
You familiar with the elephant seal or the cheetah? They suffered almost complete extinction and were able to bounce back. There has hardly been a megafaunal extinction since the end Pleistocene.
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What "unusual" migrations were occuring during this period, at a rate fast enough to disrupt long-standing human cultural stances?
Oh things like this which show very little equilibrium
BMC Genet. 2003 Oct 16 [Epub ahead of print]. Links
Mitochondrial DNA transit between West Asia and North Africa inferred from U6 phylogeography.
Maca-Meyer N, Gonzalez AM, Pestano J, Flores C, Larruga JM, Cabrera VM.
Background: World-wide phylogeographic distribution of human complete mitochondrial DNA sequences suggested a West Asian origin for the autochthonous North African lineage U6. We report here a more detailed analysis of this lineage, unraveling successive expansions that affected not only Africa but neighboring regions such as the Near East, the Iberian Peninsula and the Canary Islands.Results: Divergence times, geographic origin and expansions of the U6 mitochondrial DNA clade, have been deduced from the analysis of 14 complete U6 sequences, and 56 different haplotypes, characterized by hypervariable segment sequences and RFLPs. Conclusions: The most probable origin of the proto-U6 lineage was the Near East. Around 30,000 years ago it spread to North Africa where it represents a signature of regional continuity. Subgroup U6a reflects the first African expansion from the Maghrib returning to the east in Paleolithic times. Derivative clade U6a1 signals a posterior movement from East Africa back to the Maghrib and the Near East. This migration coincides with the probable Afroasiatic linguistic expansion. U6b and U6c clades, restricted to West Africa, had more localized expansions. U6b probably reached the Iberian Peninsula during the Capsian diffusion in North Africa. Two autochthonous derivatives of these clades (U6b1 and U6c1) indicate the arrival of North African settlers to the Canarian Archipelago in prehistoric times, most probably due to the Saharan desiccation. The absence of these Canarian lineages nowadays in Africa suggests important demographic movements in the western area of this Continent.
Eur J Hum Genet. 2003 Oct 8 [Epub ahead of print]. Related Articles, Links
Human X-chromosomal lineages in Europe reveal Middle Eastern and Asiatic contacts.
Xiao FX, Yotova V, Zietkiewicz E, Lovell A, Gehl D, Bourgeois S, Moreau C, Spanaki C, Plaitakis A, Moisan JP, Labuda D.
1Centre de Recherche, Hopital Sainte-Justine, Montreal, Quebec, Canada.
Within Europe, classical genetic markers, nuclear autosomal and Y-chromosome DNA polymorphisms display an east-west frequency gradient. This has been taken as evidence for the westward migration of Neolithic farmers from the Middle East. In contrast, most studies of mtDNA variation in Europe and the Middle East have not revealed clinal distributions. Here we report an analysis of dys44 haplotypes, consisting of 35 polymorphisms on an 8 kb segment of the dystrophin gene on Xp21, in a sample of 1203 Eurasian chromosomes. Our results do not show a significant genetic structure in Europe, though when Middle Eastern samples are included a very low but significant genetic structure, rooted in Middle Eastern heterogeneity, is observed. This structure was not correlated to either geography or language, indicating that neither of these factors are a barrier to gene flow within Europe and/or the Middle East. Spatial autocorrelation analysis did not show clinal variation from the Middle East to Europe, though an underlying and ancient east-west cline across the Eurasian continent was detected. Clines provide a strong signal of ancient major population migration(s), and we suggest that the observed cline likely resulted from an ancient, bifurcating migration out of Africa that influenced the colonizing of Europe, Asia and the Americas. Our study reveals that, in addition to settlements from the Near East, Europe has been influenced by other major population movements, such as expansion(s) from Asia, as well as by recent gene flow from within Europe and the Middle East.European Journal of Human Genetics advance online publication, 8 October 2003; doi:10.1038/sj.ejhg.5201097
There has never been equilibrium
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How many times do I have to point out that humans, and human culture, coevolved with elephants in Africa? Whether there were up and down cycles is irrelevant (do you have counterevidence?), although yes, one would expect small up and down cycles. Even a most nomadic tribe taking on highly destructive social memes isn't a threat to elephants in general - just in their particular region.
Interesting that you argue this here but have no problem assuming it for the extinction of mammoths and all the megafauna throughout Europe all the way to Patagonia....and humans actualyl had contact with all of these animals long before the end Pleistocene extinctions i.e. cave paintings, 30,000 year old bone carvings in Siberia...so they had a really bad cycle..suddenly?
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I'm not arguing that elephants were nearly wiped out by natives. I'm arguing that because of coevolution, that they *weren't*, and that there would just be the typical up and down cycles, nothing dramatic. *You* were the one arguing about instability, and I was mentioning that the population change that you referred to was due to a new population coming in, with a new "land of plenty" situation - europeans with guns, and the ivory trade.
What is the negative selection agianst the natives? Co-evolution is not enough as any mutation/behavior that provides an advantage should spread rapidly...why would they not have recognized their own land of plenty..especially if you argue that there were cycles where they did? What would have brought them back to not doing it? Why is there no evidence that they did do it? Also African culture is not monolithic. There are some groups that hunt elephants, others that do not. You cannot tell me that hunters in the Congo are anything like the !Kung.
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You seem to expect *every* species that humans encounter to get hunted out of existance. That seems pretty preposterous to me. Different animals live in different types of geographic environments, and with different organizational structures. Furthermore, one would expect that the more recent migrants from Africa would still retain more of the social structure that they lived on before, while the further in the arctic they get, the more their culture will become dependant on hunting the abundant wild game.
As preposterous as hunting a single species to extinction as it become harder and harder to find yet ignoring other species that are abundant and that we know humans have also hunted since the same time period. And not everything that went extinct was in the arctic. The youngest fossils for many of these species do not occur at the highest latitudes. And mammoths and a lot of the extinct megafauna were nowhere near the arctic or not exclusively. Giant ground sloths certainly were not.
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How do you come to the conclusion that they learned in *one generation*?
from the paper I cited "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. "
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Provide one piece of evidence that they were "left alone". They weren't hunted to extinction. That hardly means that they were "left alone".
See the genetic diversity papers...no sign of any bottleneck in the time that all the megafauna is going extinct. Significant hunting would leave an imprint especially given it was not very long ago.
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Even the hunting-only people (which, again, I am not one*) seldom believe that the species were hunted to extinction - only that they were hunted to the point where they were unable to recover.
What point would that be? Seriously, a single breeding pair may have all that had been left of the cheetah yet they are not extinct. Elephant seals were decimated, they are stil there...no whales have gone extinct.
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Please, Mammothus. You know very well that the ability to sustain an animal is generally relative to its size (at least, I *assume* that you do). The more massive it is, the more calories it needs to consume, and the smaller its population will be (on average).
Ok so there were not millions of buffalo, elephants in the millions, the population size of mammoths..2 maybe 3? I guess I will have to take your word for this.
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Actually, I would expect them to be harder, because they won't preserve as well.
Interesting then that many major mammoth finds are in places in the US that are not permafrost. Actual habitation would be easier to find in non permafrost since the tundra tends to shift around so much that you never find fossils intact and the layers get mixed so that you cnanot do stratiography...not so outside the tundra.
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Sounds like I'm advocating a "multiple causes" hypothesis, doesn't it? I'm stating that disease and climate together isn't enough - what also is needed is changes in population through hunting of the animals, hunting predators, hunting prey, etc; altering of the flora; etc.
Except that megafaunal extinctions happened frequently prior to the end Pleistocene and at times where human causes could not have been a factor..so clearly humans are not needed for extinction to occur whether they played a role in this particular extinction or not.
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Yes. "Only have to kill of the young". Now, where has this happened to cause a species to go extinct?
Those of us who do not view the end Pleistocene extinctions as a closed issue are trying to find out...Peter Dazsak is doing this type of research for modern extinctions. Exactly how much do you really think is known about extinction in any case?
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I'll repeat. Now where has this happened to cause a species to go extinct?
When has there been an equivalent situation to the end Pleistocene regarding immunlogically naive species? There is somne evidence that Xmas Island rats went extinct by introduction of pathogens from ship rats..we are doing the molecular work now...there is also evidence that the thylacine was brought down by disease and not purely by hunting....though some advocates claim it is still alive in the outback.
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They need not be on the scale of the end of the Pleistocene. What you are asking for is essentially impossible, since humans had, after this, moved into all of the world's major land masses. However, extinctions relative to the sizes of the land masses that were moved into after this point, clearly due to overhunting and other human-related causes, are quite observed.
Why would they not be on this scale? Land of plenty..no negative selection...human population only recently became so tremendous...overkill should have been widely supportable yet write up a list of the number of megafauna that went extinct at the end Pleistocene and then do the same for the time since then..what do you think you see?
Clearly birth rate isn't a problem - the issue is how much resources are there for people to survive on. Initially, there are vast resources. Consequently, one expects, in the absense of social memes preventing it, a population boom.
Parrots are quite intelligent, and can learn things such as being able to recognize the difference between similar objects (size, shape, color, etc) and understand the concept of "names" for objects, and yet have tiny brains.
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