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Thread: Synergistic Roles of Climate Warming and Human Occupation in Patagonian Megafaunal Extinctions During the Last Deglaciation

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    Synergistic Roles of Climate Warming and Human Occupation in Patagonian Megafaunal Extinctions During the Last Deglaciation

    It would be weird had continental megafauna been wiped out by humans in the Americas but not in Africa or the tropics of Asia. The famous overkill hypothesis omits to explain for example why hindgut digesters like elephants and rhinos were hit much harder than foregut fermenters such as ruminants and kangaroos, or why coastal mammals were not severely impacted till industrial-scale slaughter in seal fisheries.

    http://advances.sciencemag.org/content/2/6/e1501682

    The causes of Late Pleistocene megafaunal extinctions (60,000 to 11,650 years ago, hereafter 60 to 11.65 ka) remain contentious, with major phases coinciding with both human arrival and climate change around the world. The Americas provide a unique opportunity to disentangle these factors as human colonization took place over a narrow time frame (~15 to 14.6 ka) but during contrasting temperature trends across each continent. Unfortunately, limited data sets in South America have so far precluded detailed comparison. We analyze genetic and radiocarbon data from 89 and 71 Patagonian megafaunal bones, respectively, more than doubling the high-quality Pleistocene megafaunal radiocarbon data sets from the region. We identify a narrow megafaunal extinction phase 12,280 ± 110 years ago, some 1 to 3 thousand years after initial human presence in the area. Although humans arrived immediately prior to a cold phase, the Antarctic Cold Reversal stadial, megafaunal extinctions did not occur until the stadial finished and the subsequent warming phase commenced some 1 to 3 thousand years later. The increased resolution provided by the Patagonian material reveals that the sequence of climate and extinction events in North and South America were temporally inverted, but in both cases, megafaunal extinctions did not occur until human presence and climate warming coincided. Overall, metapopulation processes involving subpopulation connectivity on a continental scale appear to have been critical for megafaunal species survival of both climate change and human impacts.

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    H. sapiens proper, meaning African sapiens was not a big game hunter. Today's African fauna is called "Pleistocene Fauna" everywhere else because everywhere else it was hunted down by men and eaten. Returning to people, only archaics or Neanderthal-sapiens hybrids ever hunted the megafauna to any great extent.

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    Quote Originally Posted by Shadow View Post
    H. sapiens proper, meaning African sapiens was not a big game hunter. Today's African fauna is called "Pleistocene Fauna" everywhere else because everywhere else it was hunted down by men and eaten. Returning to people, only archaics or Neanderthal-sapiens hybrids ever hunted the megafauna to any great extent.
    Though the living African HGs do hunt big game they still depend far more on gathering resources by hand, without reliance on fashioned weapons. This kind of Pleistocene or early Holocene economy stands in contrast to the assumption underlying the overkill hypothesis, which is that all expanding Pleistocene populations, such as the first aboriginal Australians or native Americans, were more similar to the famous Fuegian s in depending heavily upon weapons for their subsistence. The economy and ecology of the Fuegians surely fits a cold temperate climate as in Europe or North America, but they are extreme among the HGs studied by western anthropologists, and it was probably atypical as a lifestyle even back in the Pleistocene.

    The tropical African fauna actually did suffer mass extinctions of the Late Pleistocene type far earlier during the time of Homo erectus and is attributed to a change of climate. At this time were the extinction of all African machairodont cats and many of the continent's elephants, which more closely matches the terminal Pleistocene extinctions than the disasters on the islands of Hawaii or New Zealand following the arrival of Polynesians who undoubtedly created late extinctions by overkill. Even before the Neolithic began primitive economies were diverse and must have had different ecological impacts.

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    Quote Originally Posted by Shadow View Post
    H. sapiens proper, meaning African sapiens was not a big game hunter. Today's African fauna is called "Pleistocene Fauna" everywhere else because everywhere else it was hunted down by men and eaten. Returning to people, only archaics or Neanderthal-sapiens hybrids ever hunted the megafauna to any great extent.
    I notice that big wild animals have survived to this day in numbers only in the far north, designated national parks of North America, or most especially in Africa.

    Here are some drawings of how the Latin American megafauna may have looked.




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    As it happens, the South American Aw (savannah climate) vegetation was less grassy back then and there were more browsers, and in particular, more hindgut digesters. I in fact remember reading there's a reason why African savannahs are so grassy, because the soil is weird compared to other Aw areas of the world in a way that prevents more trees and bushes. In turn there's more grass per acreage in Aw Africa than elsewhere, so similar biomes in places like India and South America never have had the diversity of grazing mammals. Its the rise of savannah-type grasses spurred the diversification of the ruminant herbivores that proved relatively immune to climate change - I don't remember why but this is statistical fact.

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    Homo erectus was a big game hunter. He did not have to sophistication to exterminate his fauna through feeding Neanderthals did do some of this. Mammoth population density dropped as they increased so did the cave bear. You mentioned the machairodont cats. In Africa they remained primitive throughout the Pleistocene and relatively small and died out before H. erectus. On the other hand similar cats in Europe, Homotherium, became extinct or greatly reduced in competition with Neanderthals. They were gone before sapiens arrived. But Homotherium lived on in N. America right up to the terminal Pleistocene in the north in the form of Homotherium serum, a very close relative to what was found in Europe.

    African big game hunting apparently never resulted in any species extinction. I know of no tribe in Africa ever living off of elephants, for instance.. Pigmies and bushmen did hunt them but on a very low scale.

    Meanwhile, in Europe, Asia (the straight tusked elephant or Southern Elephant) and America they all went extinct.

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    Quote Originally Posted by Shadow View Post
    Homo erectus was a big game hunter. He did not have to sophistication to exterminate his fauna through feeding Neanderthals did do some of this. Mammoth population density dropped as they increased so did the cave bear.
    Cave bears were rarely hunted by early man, at lest not in the UP period. Unlike lions they rarely feature in cave or portable art and their cultural or economic importance is not certain. Anyway they seem to have vanished into the brown bear gene pool same as neanderthals did into modern humans - up to you if that's a real extinction or just reticulated evolution at work. Dietary differences between neanderthals and UP Europeans suggest neanderthals also "died out" for ecological and climatic reasons around the same time.

    You mentioned the machairodont cats. In Africa they remained primitive throughout the Pleistocene and relatively small and died out before H. erectus. On the other hand similar cats in Europe, Homotherium, became extinct or greatly reduced in competition with Neanderthals. They were gone before sapiens arrived. But Homotherium lived on in N. America right up to the terminal Pleistocene in the north in the form of Homotherium serum, a very close relative to what was found in Europe.
    In Europe Homotherium was also a contemporary of modern Homo sapiens, obviously having outlived the neanderthals, and in Africa all machairodonts disappeared 40,000 to 70,000 years ago. Neanderthals likely had little ecological impact compared to later Pleistocene people but I still doubt the overkill idea.

    African big game hunting apparently never resulted in any species extinction. I know of no tribe in Africa ever living off of elephants, for instance.. Pigmies and bushmen did hunt them but on a very low scale.

    Meanwhile, in Europe, Asia (the straight tusked elephant or Southern Elephant) and America they all went extinct.
    Palaeoloxdon island dwarves persisted into the historical period on Tilos and were even depicted once in Egyptian art. On Wrangel Island woolly mammoths persisted to 3,700 years ago. These dates are not earliest Holocene.




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    Mammoths hung on until the UP but were not widespread. Cave bears were rarely hunted in the UP because they were almost extinct by then. Neanderthals must have had something to do with this. I have never heard it said cave bears were absorbed by brown bears. Do you have an references on this? I believe Homotherium was done before the UP in Europe but maybe that is incorrect, I will have to check Kurten.

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    Quote Originally Posted by Shadow View Post
    Mammoths hung on until the UP but were not widespread. Cave bears were rarely hunted in the UP because they were almost extinct by then. Neanderthals must have had something to do with this. I have never heard it said cave bears were absorbed by brown bears. Do you have an references on this? I believe Homotherium was done before the UP in Europe but maybe that is incorrect, I will have to check Kurten.
    I think the information about cave bears is from John Hawks. Seems now that when related, interfertile species exist sympatrically, assimilation is more likely a fate than real extinction. Such a pattern is proven in bears, canids, hominins and mammoths now.

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    Quote Originally Posted by Catterick View Post
    I think the information about cave bears is from John Hawks. Seems now that when related, interfertile species exist sympatrically, assimilation is more likely a fate than real extinction. Such a pattern is proven in bears, canids, hominins and mammoths now.
    Probably so.

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