119-691: The Late Pleistocene to the beginning of the Holocene saw the extinction of the majority of the world's megafauna (typically defined as animal species having body masses over 44 kilograms (97 lb)), which resulted in a collapse in faunal density and diversity across the globe. The extinctions during the Late Pleistocene are differentiated from previous extinctions by its extreme size bias towards large animals (with small animals being largely unaffected), and widespread absence of ecological succession to replace these extinct megafaunal species, and
238-477: A biodiversity hotspot . In Southeastern Asia, high mountain ranges form tongues of Palearctic flora and fauna in northern Indochina and southern China . Isolated small outposts ( sky islands ) occur as far south as central Myanmar (on Nat Ma Taung , 3,050 m; 10,010 ft), northernmost Vietnam (on Fan Si Pan , 3,140 m; 10,300 ft) and the high mountains of Taiwan . The realm contains several important freshwater ecoregions as well, including
357-503: A cause of the extinctions argue that statistical modelling validates that relatively low-level hunting can have significant effect on megafauna populations due to their slow life cycles, and that hunting can cause top-down forcing trophic cascade events that destabilize ecosystems. The Second-Order Predation Hypothesis says that as humans entered the New World they continued their policy of killing predators, which had been successful in
476-536: A change in the use of coastal resources and advancements in marine technology. The reasons for these changes have not been confirmed; various triggering mechanisms have been theorized such as climate change , the arrival of new people, or the struggle for resources. The South American land mammal age , the Lujanian , corresponds with the late Pleistocene. The Lujanian is a geologic period from 0.8 - 0.11Ma specifically for prehistoric South American fauna. There
595-529: A computer model, the Pleistocene extinction model (PEM), which, using the same assumptions and values for all variables (herbivore population, herbivore recruitment rates, food needed per human, herbivore hunting rates, etc.) other than those for hunting of predators. It compares the overkill hypothesis (predator hunting = 0) with second-order predation (predator hunting varied between 0.01 and 0.05 for different runs). The findings are that second-order predation
714-625: A divide among researches about when and how megafaunal species went extinct. There are at least three hypotheses regarding the extinction of the Australian megafauna : This theory is based on evidence of megafauna surviving until 40,000 years ago, a full 30,000 years after homo sapiens first landed in Australia, and thus that the two groups coexisted for a long time. Evidence of these animals existing at that time come from fossil records and ocean sediment. To begin with, sediment core drilled in
833-433: A few thousand years, around the 45,000 years ago, suggesting a rapid extinction event. In addition, fossils found at South Walker Creek, which is the youngest megafauna site in northern Australia, indicate that at least 16 species of megafauna survived there until 40,000 years ago. Furthermore, there is no firm evidence of homo sapiens living at South Walker Creek 40,000 years ago, therefore no human cause can be attributed to
952-527: A more continental climate than Pleistocene or modern (post-Pleistocene, interglacial) North America. The animals that became extinct actually should have prospered during the shift from mixed woodland-parkland to prairie, because their primary food source, grass, was increasing rather than decreasing. Although the vegetation did become more spatially specialized, the amount of prairie and grass available increased, which would have been good for horses and for mammoths, and yet they became extinct. This criticism ignores
1071-422: A period of cooling. In between these extremes megafaunal extinctions have occurred progressively in such places as North America, South America and Madagascar with no climatic commonality. The only common factor that can be ascertained is the arrival of humans. This phenomenon appears even within regions. The mammal extinction wave in Australia about 50,000 years ago coincides not with known climatic changes, but with
1190-468: A reliable chronology. North American extinctions (noted as herbivores ( H ) or carnivores ( C )) included: The survivors are in some ways as significant as the losses: bison ( H ), grey wolf ( C ), lynx ( C ), grizzly bear ( C ), American black bear ( C ), deer (e.g. caribou , moose , wapiti (elk) , Odocoileus spp.) ( H ), pronghorn ( H ), white-lipped peccary ( H ), muskox ( H ), bighorn sheep ( H ), and mountain goat ( H );
1309-507: A sufficient mix of food to avoid toxins, they extract enough nutrition from forage to reproduce effectively and the timing of their gestation is not an issue. Of course, this criticism ignores the obvious fact that present-day horses are not competing for resources with ground sloths, mammoths, mastodons, camels, llamas, and bison. Similarly, mammoths survived the Pleistocene Holocene transition on isolated, uninhabited islands in
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#17327903882051428-576: A true domestic dog have been dated to 14,200 years ago. Domestication first happened in Eurasia but could have been anywhere from Western Europe to East Asia. Domestication of other animals such as cattle, goats, pigs, and sheep did not begin until the Holocene when settled farming communities became established in the Near East. The cat was probably not domesticated before c. 7500 BC at
1547-489: A very few show unambiguous evidence of human hunting of any type of prey whatsoever." Eugene S. Hunn suggests that the birthrate in hunter-gatherer societies is generally too low, that too much effort is involved in the bringing down of a large animal by a hunting party, and that in order for hunter-gatherers to have brought about the extinction of megafauna simply by hunting them to death, an extraordinary amount of meat would have had to have been wasted. Proponents of hunting as
1666-405: Is also one of the world's most endangered biogeographic regions; only 4% of the region's original vegetation remains, and human activities, including overgrazing , deforestation , and conversion of lands for pasture, agriculture, and urbanization, have degraded much of the region. Formerly the region was mostly covered with forests and woodlands, but heavy human use has reduced much of the region to
1785-488: Is apt to be water. Large animals also store more fat in their bodies than do medium-sized animals and this should have allowed them to compensate for extreme seasonal fluctuations in food availability. Late Pleistocene The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy , also known as the Upper Pleistocene from a stratigraphic perspective. It
1904-473: Is clear, therefore, that we are now in an altogether exceptional period of the earth's history. We live in a zoologically impoverished world, from which all the hugest, and fiercest, and strangest forms have recently disappeared; and it is, no doubt, a much better world for us now they have gone. Yet it is surely a marvellous fact, and one that has hardly been sufficiently dwelt upon, this sudden dying out of so many large mammalia, not in one place only but over half
2023-482: Is coincident with increasing aridity. Increasingly arid conditions in southeastern Australia during the late Pleistocene may have stressed megafauna, and contributed to their decline. In Sahul (a former continent composed of Australia and New Guinea ), the sudden and extensive spate of extinctions occurred earlier than in the rest of the world. Most evidence points to a 20,000 year period after human arrival circa 63,000 BCE, but scientific argument continues as to
2142-503: Is conducive for preserving fossils . Neanderthal hominins ( Homo neanderthalensis ) inhabited Eurasia until becoming extinct between 40 and 30 ka, towards the end of the Pleistocene and possibly into the early Holocene and were replaced with modern humans ( Homo sapiens ) who emerged from East Africa about 195,000 years ago. Neanderthals co-existed with the Homo sapiens until they died out. In Eurasia, extinction happened throughout
2261-610: Is due to the lack of chronological information. The resemblance of Late Pleistocene species in Northern Africa to modern animals is the same as in Southern Africa but it's extremely difficult to date when these fauna came into place because of the lack of reliable samples from the mid-Pleistocene. Most of the significant fossil records are from the Maghreb because of its geology which helps to create deep caves which
2380-432: Is evidence of human habitation in mainland Australia , Indonesia , New Guinea and Tasmania from c. 45,000 BC. The finds include rock engravings, stone tools and evidence of cave habitation. In Australia, there are sites which show evidence of pollen records from the Late Pleistocene and they are mostly found in more temperate regions of the continent. Some megafauna decreased in size over time, while others remained
2499-399: Is evidence that anthropogenic fire use had major impacts on the local environments in both Australia and North America. At the end of the 19th and beginning of the 20th centuries, when scientists first realized that there had been glacial and interglacial ages, and that they were somehow associated with the prevalence or disappearance of certain animals, they surmised that the termination of
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#17327903882052618-620: Is evidence that the average size of mammalian fauna declined over the course of the Quaternary, a phenomenon that was likely linked to disproportionate hunting of large animals by humans. Extinction through human hunting has been supported by archaeological finds of mammoths with projectile points embedded in their skeletons, by observations of modern naive animals allowing hunters to approach easily and by computer models by Mosimann and Martin, and Whittington and Dyke, and most recently by Alroy. A number of objections have been raised regarding
2737-542: Is intended to be the fourth division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently defined as the time between c. 129,000 and c. 11,700 years ago. The late Pleistocene equates to the proposed Tarantian Age of the geologic time scale , preceded by the officially ratified Chibanian (commonly known as the Middle Pleistocene). The beginning of the Late Pleistocene
2856-534: Is more consistent with extinction than is overkill (results graph at left). The Pleistocene extinction model is the only test of multiple hypotheses and is the only model to specifically test combination hypotheses by artificially introducing sufficient climate change to cause extinction. When overkill and climate change are combined they balance each other out. Climate change reduces the number of plants, overkill removes animals, therefore fewer plants are eaten. Second-order predation combined with climate change exacerbates
2975-667: Is rare, though megafauna exploitation has been documented at a number of sites. Fishtail points rapidly disappeared after the extinction of the megafauna, and were replaced by other styles more suited to hunting smaller prey. Some authors have proposed the "Broken Zig-Zag" model, where human hunting and climate change causing a reduction in open habitats preferred by megafauna were synergistic factors in megafauna extinction in South America. A scarcity of reliably dated megafaunal bone deposits has made it difficult to construct timelines for megafaunal extinctions in certain areas, leading to
3094-545: Is still heavily debated what caused the extinctions. Bison occidentalis and Bison antiquus , an extinct subspecies of the smaller present-day bison, survived the late Pleistocene period, between about 12 and 11 ka ago. Clovis people depended on these bison as their major food source. Earlier kills of camels, horses, and muskoxen found at Wally's beach were dated to 13.1–13.3 ka B.P. Over 50 genera (~ 83%) of megafauna in South and North America went extinct during
3213-624: Is the same scheme that persists today, with relatively minor revisions, and the addition of two more realms: Oceania and the Antarctic realm . The Palearctic realm includes mostly boreal/subarctic-climate and temperate-climate ecoregions, which run across Eurasia from western Europe to the Bering Sea . The boreal and temperate Euro-Siberian region is the Palearctic's largest biogeographic region, which transitions from tundra in
3332-703: Is the transition between the end of the Penultimate Glacial Period and the beginning of the Last Interglacial around 130,000 years ago (corresponding with the beginning of Marine Isotope Stage 5 ). The Late Pleistocene ends with the termination of the Younger Dryas , some 11,700 years ago when the Holocene Epoch began. The term Upper Pleistocene is currently in use as a provisional or "quasi-formal" designation by
3451-633: The Americas , Madagascar and New Zealand without the earliest humans. The overkill hypothesis, a variant of the hunting hypothesis, was proposed in 1966 by Paul S. Martin, Professor of Geosciences Emeritus at the Desert Laboratory of the University of Arizona . Circumstantially, the close correlation in time between the appearance of humans in an area and extinction there provides weight for this scenario. Radiocarbon dating has supported
3570-607: The Bering land bridge which joined Alaska to Siberia . The last Ice Age was followed by the Late Glacial Interstadial , a period of global warming to 12.9 ka, and the Younger Dryas , a return to glacial conditions until 11.7 ka. Paleoclimatology holds that there was a sequence of stadials and interstadials from about 16 ka until the end of the Pleistocene. These were the Oldest Dryas (stadial),
3689-487: The Bering land bridge , and have very similar mammal and bird fauna, with many Eurasian species having moved into North America, and fewer North American species having moved into Eurasia. Many zoologists consider the Palearctic and Nearctic to be a single Holarctic realm . The Palearctic and Nearctic also share many plant species, which botanists call the Arcto-Tertiary Geoflora . The lands bordering
Late Pleistocene extinctions - Misplaced Pages Continue
3808-881: The Bølling oscillation (interstadial), the Older Dryas (stadial), the Allerød oscillation (interstadial) and finally the Younger Dryas. The end of the Younger Dryas marks the boundary between the Pleistocene and Holocene Epochs. Hominids in all parts of the world were still culturally and technologically in the Palaeolithic (Old Stone) Age . Tools and weapons were basic stone or wooden implements. Nomadic tribes followed moving herds. Non-nomadics acquired their food by gathering and hunting . Its present physical geography and climate have changed over time caused by
3927-647: The International Union of Geological Sciences (IUGS). Although the three oldest ages of the Pleistocene (the Gelasian , the Calabrian and the Chibanian ) have been officially defined, the late Pleistocene has yet to be formally defined. Following the brief Last Interglacial warm period (~130–115,000 years ago), where temperatures were comparable to or warmer than the Holocene, the Late Pleistocene
4046-693: The Japanese archipelago has been traced to prehistoric times between 40,000 BC and 30,000 BC. The earliest fossils are radiocarbon dated to c. 35,000 BC. An archeological record of Neanderthals has been found in Asia along with records of two other hominin populations, the Denisovans and Homo floresiensis . Japan was once linked to the Asian mainland by land bridges via Hokkaido and Sakhalin Island to
4165-570: The Mediterranean Sea in southern Europe, north Africa, and western Asia are home to the Mediterranean Basin ecoregions, which together constitute the world's largest and most diverse mediterranean climate region of the world, with generally mild, rainy winters and hot, dry summers. The Mediterranean basin's mosaic of Mediterranean forests, woodlands, and scrub are home to 13,000 endemic species. The Mediterranean basin
4284-651: The Mediterranean Sea until 4,000 to 7,000 years ago, as well as on Wrangel Island in the Siberian Arctic. Additionally, large mammals should have been able to migrate, permanently or seasonally, if they found the temperature too extreme, the breeding season too short, or the rainfall too sparse or unpredictable. Seasons vary geographically. By migrating away from the equator , herbivores could have found areas with growing seasons more favorable for finding food and breeding successfully. Modern-day African elephants migrate during periods of drought to places where there
4403-535: The Nile Valley as the Sahara was transformed from grassland to desert. The Nazlet Khater skeleton was found in 1980 and has been radiocarbon dated to between 30,360 and 35,100 years ago. Most of the knowledge of the Late Pleistocene is obtained from regions like Morocco , Algeria , Tunisia , some coastal regions of Maghreb , Libya and Egypt . The only issue with interpreting the data from this region
4522-850: The North American land mammal age scale, the Rancholabrean spans the time from c. 240,000 years ago to c. 11,000 years ago. It is named after the Rancho La Brea fossil site in California , characterized by extinct forms of bison in association with other Pleistocene species such as the mammoth . During the Late Pleistocene about 35 genera of megafauna went extinct including species such as mastodons , saber-toothed cats and giant ground sloths . Some other species went extinct in North America but not globally. it
4641-458: The Wisconsin ice sheet could have placed enough thermal stress on cold-adapted mammals to cause them to die. Their heavy fur, which helps conserve body heat in the glacial cold, might have prevented the dumping of excess heat, causing the mammals to die of heat exhaustion. Large mammals, with their reduced surface area-to-volume ratio , would have fared worse than small mammals. A study covering
4760-526: The mammoth , mastodon , and Irish elk became extinct. Upper Paleolithic people also made paintings and engravings on walls. Cave paintings have been found at Lascaux in the Dordogne which may be more than 17,000 years old. These are mainly buffalo , deer , and other animals hunted by humans. Later paintings occur in caves throughout the world, including Altamira , Spain, and in India, Australia, and
4879-443: The regime shift of previously established faunal relationships and habitats as a consequence. The timing and severity of the extinctions varied by region and are thought to have been driven by varying combinations of human and climatic factors. Human impact on megafauna populations is thought to have been driven by hunting ("overkill"), as well as possibly environmental alteration. The relative importance of human vs climatic factors in
Late Pleistocene extinctions - Misplaced Pages Continue
4998-531: The sclerophyll shrublands known as chaparral , matorral , maquis , or garrigue . Conservation International has designated the Mediterranean basin as one of the world's biodiversity hotspots . A great belt of deserts , including the Atlantic coastal desert , Sahara Desert, and Arabian Desert , separates the Palearctic and Afrotropic ecoregions. This scheme includes these desert ecoregions in
5117-514: The straight-tusked elephant and the narrow-nosed rhinoceros generally going extinct earlier than cold adapted species like the woolly mammoth and woolly rhinoceros . Climate change has been considered a probable major factor in the extinctions, possibly in combination with human hunting. Extinctions in North America were concentrated at the end of the Late Pleistocene, around 13,800–11,400 years Before Present, which were coincident with
5236-628: The temperate rain forests of the Euxine-Colchic deciduous forests ecoregion. Central Asia and the Iranian plateau are home to dry steppe grasslands and desert basins, with montane forests, woodlands, and grasslands in the region's high mountains and plateaux. In southern Asia the boundary of the Palearctic is largely altitudinal. The middle altitude foothills of the Himalaya between about 2,000–2,500 m (6,600–8,200 ft) form
5355-482: The Alps and interglacials (temperate phase). The evidence of the changes in climatic conditions was from fragmentary sequences in formerly glaciated areas in northern Europe . The only domesticated animal in the Pleistocene was the dog , which evolved from the grey wolf into its many modern breeds . It is believed that the grey wolf became associated with hunter-gatherer tribes around 15 Ka. The earliest remains of
5474-555: The Americas were virtually simultaneous, spanning only 3000 years at most. Overall, during the Late Pleistocene about 65% of all megafaunal species worldwide became extinct, rising to 72% in North America, 83% in South America and 88% in Australia, with all mammals over 1,000 kilograms (2,200 lb) becoming extinct in Australia and the Americas, and around 80% globally. Africa, South Asia and Southeast Asia experienced more moderate extinctions than other regions. The Late Pleistocene saw
5593-514: The Indian Ocean off the SW coast of Australia indicate the existence of a fungus called Sporormiella, which survived off the dung of plant-eating mammals. The abundance of these spores in the sediment prior to 45,000 years ago indicates that many large mammals existed in the southwest Australian landscape until that point. The sediment data also indicates that the megafauna population collapsed within
5712-526: The Indian subcontinent is uncertain due to a lack of reliable dating. Similar issues have been reported for Chinese sites, though there is no evidence for any of the megafaunal taxa having survived into the Holocene in that region. Extinctions in Southeast Asia and South China have been proposed to be the result of environmental shift from open to closed forested habitats. The Palearctic realm spans
5831-603: The Late Pleistocene. Some species which went extinct at the end of the Late Pleistocene in Southern Africa are the giant warthog , long-horn buffalo, Southern springbok , etc. These species were common because their distribution changed in response to climatic influences on vegetation. Carnivores were more widespread due to their varying habitat requirements. In Egypt , the Late (or Upper) Palaeolithic began sometime after 30,000 BC. People in North Africa had relocated to
5950-603: The North American Great Lakes region, the population declines of mastodons and mammoths have been found to correlate with climatic fluctuations during the Younger Dryas rather than human activity. In the Argentine Pampas, the flooding of vast swathes of the once much larger Pampas grasslands may have played a role in the extinctions of its megafaunal assemblages. Critics object that since there were multiple glacial advances and withdrawals in
6069-514: The Old World but because they were more efficient and because the fauna, both herbivores and carnivores, were more naive, they killed off enough carnivores to upset the ecological balance of the continent, causing overpopulation , environmental exhaustion, and environmental collapse. The hypothesis accounts for changes in animal, plant, and human populations. The scenario is as follows: The second-order predation hypothesis has been supported by
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#17327903882056188-410: The Pleistocene ice age might be an explanation for the extinctions. The most obvious change associated with the termination of an ice age is the increase in temperature. Between 15,000 BP and 10,000 BP, a 6 °C increase in global mean annual temperatures occurred. This was generally thought to be the cause of the extinctions. According to this hypothesis, a temperature increase sufficient to melt
6307-673: The Pleistocene but those that happened during the Later Pleistocene were of megafauna and there were no replacements for the extinct species. Some Molluscan species went extinct but not on the same scale as the mammals living during the time. Some examples of species which extinct without replacements include the Straight-tusked elephant ( Palaeoloxodon antiquus ), Giant deer ( Megaloceros giganteus ), cave bear ( Ursus spelaeus ) and woolly rhinoceros ( Coelodonta antiquitatis ). Several large mammalian species including
6426-479: The Pleistocene extinction model. Also, the control of population sizes by predators is not fully supported by observations of modern ecosystems. The hypothesis further assumes decreases in vegetation due to climate change, but deglaciation doubled the habitable area of North America. Any vegetational changes that did occur failed to cause almost any extinctions of small vertebrates, and they are more narrowly distributed on average, which detractors cite as evidence against
6545-662: The Pleistocene populations particularly vulnerable to changes in their environment. Studies propose that the annual mean temperature of the current interglacial that we have seen for the last 10,000 years is no higher than that of previous interglacials, yet most of the same large mammals survived similar temperature increases. In addition, numerous species such as mammoths on Wrangel Island and St. Paul Island survived in human-free refugia despite changes in climate. This would not be expected if climate change were responsible (unless their maritime climates offered some protection against climate change not afforded to coastal populations on
6664-482: The Pleistocene. most mega mammals (>1000kg) and large mammals (>40kg) went extinct by the end of the Late Pleistocene. During this period there was a major cooling event called the Younger Dryas and the Clovis culture of capturing game became more prominent. Diverse factors such as climate change may have triggered this extinction but it's still in debate what the major factors were. The Late Pleistocene saw
6783-680: The Sahara. Magdalenian hunter-gatherers were widespread in western Europe about 20 -12.500 cal BP years ago until the end of the Pleistocene. An example of this is the antler-working done by the human groups who lived in the Santimamine cave in the Magdalenian. They invented the earliest known harpoons using reindeer horn. Climatic conditions during the Late Pleistocene in Eurasia were predominantly cold with glaciation events happening in northern Europe , northwest Siberia and
6902-407: The arrival of humans on different continents or islands. This was compared against climate reconstructions for the last 90,000 years. The researchers found correlations of human spread and species extinction indicating that the human impact was the main cause of the extinction, while climate change exacerbated the frequency of extinctions. The study, however, found an apparently low extinction rate in
7021-479: The arrival of humans. In addition, large mammal species like the giant kangaroo Protemnodon appear to have succumbed sooner on the Australian mainland than on Tasmania, which was colonised by humans a few thousand years later. A study published in 2015 supported the hypothesis further by running several thousand scenarios that correlated the time windows in which each species is known to have become extinct with
7140-698: The basis for zoogeographic classification. In an 1858 paper for the Proceedings of the Linnean Society , British zoologist Philip Sclater first identified six terrestrial zoogeographic realms of the world: Palaearctic, Aethiopian/ Afrotropic , Indian / Indomalayan , Australasian , Nearctic , and Neotropical . The six indicated general groupings of fauna, based on shared biogeography and large-scale geographic barriers to migration. Alfred Wallace adopted Sclater's scheme for his book The Geographical Distribution of Animals , published in 1876. This
7259-412: The boundary between the Palearctic and Indomalaya ecoregions. China , Korea and Japan are more humid and temperate than adjacent Siberia and Central Asia, and are home to rich temperate coniferous, broadleaf, and mixed forests, which are now mostly limited to mountainous areas, as the densely populated lowlands and river basins have been converted to intensive agricultural and urban use. East Asia
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#17327903882057378-595: The conclusion: "The inability of climate to predict the observed population decline of megafauna, especially during the past 75,000 years, implies that human impact became the main driver of megafauna dynamics around this date." Although Africa was one of the least affected regions, the region still suffered extinctions, particularly around the Late Pleistocene-Holocene transition. These extinctions were likely predominantly climatically driven by changes to grassland habitats. The timing of extinctions on
7497-400: The continents, with around 83% of its megafauna going extinct. These extinctions postdate the arrival of modern humans in South America around 15,000 years ago. Both human and climatic factors have been attributed as factors in the extinctions by various authors. Although some megafauna has been historically suggested to have survived into the early Holocene based on radiocarbon dates this may be
7616-472: The deepest astonishment, on the changed state of [South America]. Formerly it must have swarmed with great monsters, like the southern parts of Africa, but now we find only the tapir, guanaco, armadillo, capybara; mere pigmies compared to antecedents races... Since their loss, no very great physical changes can have taken place in the nature of the Country. What then has exterminated so many living creatures? It
7735-475: The direct evidence for this includes: fossils of some megafauna found in conjunction with human remains, embedded arrows and tool cut marks found in megafaunal bones, and European cave paintings that depict such hunting. Biogeographical evidence is also suggestive: the areas of the world where humans evolved currently have more of their Pleistocene megafaunal diversity (the elephants and rhinos of Asia and Africa ) compared to other areas such as Australia ,
7854-682: The earliest, again in the Near East . A butchered brown bear patella found in Alice and Gwendoline Cave in County Clare and dated to 10,860 to 10,641 BC indicates the first known human activity in Ireland . The topography and geography of Asia were subject to frequent changes such as the creation of land bridges when sea levels dropped which helped with the expansion and migration of human populations . The first human habitation in
7973-508: The effect of climate change. (results graph at right). The second-order predation hypothesis is further supported by the observation above that there was a massive increase in bison populations. However, this hypothesis has been criticised on the grounds that the multispecies model produces a mass extinction through indirect competition between herbivore species: small species with high reproductive rates subsidize predation on large species with low reproductive rates. All prey species are lumped in
8092-569: The end of the Pleistocene (although the genus was regionally extirpated in many areas). The survival of bison into the Holocene and recent times is therefore inconsistent with the overkill scenario. By the end of the Pleistocene, when humans first entered North America, these large animals had been geographically separated from intensive human hunting for more than 200,000 years. Given this enormous span of geologic time, bison would almost certainly have been very nearly as naive as native North American large mammals. The culture that has been connected with
8211-673: The entirety of the European continent and stretches into northern Asia , through the Caucasus and central Asia to northern China , Siberia and Beringia . Extinctions were more severe in Northern Eurasia than in Africa or South and Southeast Asia. These extinctions were staggered over tens of thousands of years, spanning from around 50,000 years Before Present (BP) to around 10,000 years BP, with temperate adapted species like
8330-461: The evolutionary history of many of the megafauna, it is rather implausible that only after the last glacial maximum would there be such extinctions. Proponents of climate change as the extinction event's cause like David J. Meltzer suggest that the last deglaciation may have been markedly different from previous ones. Also, one study suggests that the Pleistocene megafaunal composition may have differed markedly from that of earlier interglacials, making
8449-479: The exact date range. In the rest of the Pacific (other Australasian islands such as New Caledonia, and Oceania ) although in some respects far later, endemic fauna also usually perished quickly upon the arrival of humans in the late Pleistocene and early Holocene. The megafaunal extinctions were already recognized as a distinct phenomenon by some scientists in the 19th century: It is impossible to reflect without
8568-401: The extinction are automatically to be preferred by default, however, any more than weaknesses in climate change arguments can be taken as supporting overkill. Some form of a combination of both factors could be plausible, and overkill would be a lot easier to achieve large-scale extinction with an already stressed population due to climate change. South America suffered among the worst losses of
8687-453: The extinction of 90% of megafauna species. Several studies provide evidence that climate change caused megafaunal extinction during the Pleistocene in Australia. One group of researchers analyzed fossilized teeth found at Cuddie Springs in southeastern Australia. By analyzing oxygen isotopes , they measured aridity, and by analyzing carbon isotopes and dental microwear texture analysis, they assessed megafaunal diets and vegetation. During
8806-402: The extinction of many mammals weighing more than 40 kilograms (88 lb), including around 80% of mammals over 1 tonne. The proportion of megafauna extinctions is progressively larger the further the human migratory distance from Africa, with the highest extinction rates in Australia, and North and South America. The increased extent of extinction mirrors the migration pattern of modern humans:
8925-419: The extinction of these megafauna. However, there is evidence of major environmental deterioration of South Water Creek 40,000 years ago, which may have caused the extinct event. These changes include increased fire, reduction in grasslands, and the loss of fresh water. The same environmental deterioration is seen across Australia at the time, further strengthening the climate change argument. Australia's climate at
9044-498: The extinctions has been the subject of long-running controversy. Major extinctions occurred in Australia-New Guinea ( Sahul ) beginning approximately 50,000 years ago and in the Americas about 13,000 years ago, coinciding in time with the early human migrations into these regions. Extinctions in northern Eurasia were staggered over tens of thousands of years between 50,000 and 10,000 years ago, while extinctions in
9163-692: The extinctions. It has been shown that vegetation changed from mixed woodland - parkland to separate prairie and woodland. This may have affected the kinds of food available. Shorter growing seasons may have caused the extinction of large herbivores and the dwarfing of many others. In this case, as observed, bison and other large ruminants would have fared better than horses, elephants and other monogastrics , because ruminants are able to extract more nutrition from limited quantities of high- fiber food and better able to deal with anti-herbivory toxins. So, in general, when vegetation becomes more specialized, herbivores with less diet flexibility may be less able to find
9282-525: The foothills of the Himalayas , and North Africa . The realm consists of several bioregions : the Euro-Siberian region; the Mediterranean Basin ; North Africa ; North Arabia ; and Western , Central and East Asia . The Palaearctic realm also has numerous rivers and lakes, forming several freshwater ecoregions. The term 'Palearctic' was first used in the 19th century, and is still in use as
9401-669: The fossil record of mainland Asia. A 2020 study published in Science Advances found that human population size and/or specific human activities, not climate change, caused rapidly rising global mammal extinction rates during the past 126,000 years. Around 96% of all mammalian extinctions over this time period are attributable to human impacts. According to Tobias Andermann, lead author of the study, "these extinctions did not happen continuously and at constant pace. Instead, bursts of extinctions are detected across different continents at times when humans first reached them. More recently,
9520-468: The further away from Africa, the more recently humans inhabited the area, the less time those environments (including its megafauna) had to become accustomed to humans (and vice versa). There are two main hypotheses to explain this extinction: There are some inconsistencies between the current available data and the prehistoric overkill hypothesis. For instance, there are ambiguities around the timing of Australian megafauna extinctions. Evidence supporting
9639-580: The heavily developed rivers of Europe , the rivers of Russia , which flow into the Arctic , Baltic , Black , and Caspian seas, Siberia 's Lake Baikal , the oldest and deepest lake on the planet, and Japan's ancient Lake Biwa . One bird family, the accentors (Prunellidae), is endemic to the Palearctic region. The Holarctic has four other endemic bird families: the divers or loons (Gaviidae), grouse (Tetraoninae), auks (Alcidae), and waxwings (Bombycillidae). There are no endemic mammal orders in
9758-438: The hunting hypothesis. Notable among them is the sparsity of evidence of human hunting of megafauna. There is no archeological evidence that in North America megafauna other than mammoths, mastodons, gomphotheres and bison were hunted, despite the fact that, for example, camels and horses are very frequently reported in fossil history. Overkill proponents, however, say this is due to the fast extinction process in North America and
9877-439: The hypothesis. In southeastern Australia, the scarcity of water during the interval in which humans arrived in Australia suggests that human competition with megafauna for precious water sources may have played a role in the extinction of the latter. One consequence of the colonisation by humans of lands previously uninhabited by them may have been the introduction of new fire regimes because of extensive fire use by humans. There
9996-524: The increased abundance and broad geographic extent of Pleistocene bison at the end of the Pleistocene, which would have increased competition for these resources in a manner not seen in any earlier interglacials. Although horses became extinct in the New World, they were successfully reintroduced by the Spanish in the 16th century—into a modern post-Pleistocene, interglacial climate. Today there are feral horses still living in those same environments. They find
10115-407: The individuals extinctions tended to occur during times of environmental change and did not correlate particularly well with human migrations. In Australia, some studies have suggested that extinctions of megafauna began before the peopling of the continent, favouring climate change as the driver. In Beringia, megafauna may have gone extinct because of particularly intense paludification and because
10234-473: The interplay of climate change , competition between species , unstable population dynamics , and hunting as well as competition by humans. The original debates as to whether human arrival times or climate change constituted the primary cause of megafaunal extinctions necessarily were based on paleontological evidence coupled with geological dating techniques. Recently, genetic analyses of surviving megafaunal populations have contributed new evidence, leading to
10353-449: The isolated and uninhabited Commander Islands for thousands of years after they had vanished from the continental shores of the north Pacific. The later disappearance of these island species correlates with the later colonization of these islands by humans. Still, there are some arguments that species responded differently to environmental changes, and no one factor by itself explains the large variety of extinctions. The causes may involve
10472-420: The issue of the Pleistocene megafauna extinctions, concluding that the extinctons were at least in part the result of human agency in combination with other factors. Discussion of the topic became more widespread during the 20th century, particularly following the proposal of the "overkill hypothesis" by Paul Schultz Martin during the 1960s. By the end of the 20th century, two "camps" of researchers had emerged on
10591-611: The land connection between Eurasia and North America flooded before the Cordilleran Ice Sheet retreated far enough to reopen the corridor between Beringia and the remainder of North America. Woolly mammoths became extirpated from Beringia because of climatic factors, although human activity also played a synergistic role in their decline. In North America, a Radiocarbon-dated Event-Count (REC) modelling study found that megafaunal declines in North America correlated with climatic changes instead of human population expansion. In
10710-508: The land surface of the globe. We cannot but believe that there must have been some physical cause for this great change; and it must have been a cause capable of acting almost simultaneously over large portions of the earth's surface, and one which, as far as the Tertiary period at least is concerned, was of an exceptional character. Several decades later in his 1911 book The World of Life (published 2 years before his death), Wallace revisited
10829-534: The late Pleistocene contains the Upper Palaeolithic stage of human development, including the early human migrations of modern humans outside of Africa, and the extinction of all archaic human species. Paleolithic Epipalaeolithic Mesolithic Neolithic The proposed beginning of the late Pleistocene is the end of the Penultimate Glacial Period (PGP) 126 ka when the Riß glaciation (Alpine)
10948-481: The list of survivors also include species which were extirpated during the Quaternary extinction event, but recolonised at least part of their ranges during the mid-Holocene from South American relict populations, such as the cougar ( C ), jaguar ( C ), giant anteater ( C ), collared peccary ( H ), ocelot ( C ) and jaguarundi ( C ). All save the pronghorns and giant anteaters were descended from Asian ancestors that had evolved with human predators. Pronghorns are
11067-409: The low probability of animals with signs of butchery to be preserved. The majority of North American taxa have too sparse a fossil record to accurately assess the frequency of human hunting of them. A study by Surovell and Grund concluded "archaeological sites dating to the time of the coexistence of humans and extinct fauna are rare. Those that preserve bone are considerably more rare, and of those, only
11186-417: The magnitude of human driven extinctions has picked up the pace again, this time on a global scale." On a related note, the population declines of still extant megafauna during the Pleistocene have also been shown to correlate with human expansion rather than climate change. The extinction's extreme bias towards larger animals further supports a relationship with human activity rather than climate change. There
11305-522: The mainland). Under normal ecological assumptions island populations should be more vulnerable to extinction due to climate change because of small populations and an inability to migrate to more favorable climes. Critics have also identified a number of problems with the continentality hypotheses. Megaherbivores have prospered at other times of continental climate. For example, megaherbivores thrived in Pleistocene Siberia , which had and has
11424-699: The megafaunal extinctions and that Africa's trans-equatorial position allowed rangeland to continue to exist between the deserts and the central forests, therefore fewer megafauna species became extinct there. Evidence in Southeast Asia, in contrast to Europe, Australia, and the Americas, suggests that climate change and an increasing sea level were significant factors in the extinction of several herbivorous species. Alterations in vegetation growth and new access routes for early humans and mammals to previously isolated, localized ecosystems were detrimental to select groups of fauna. Some evidence from Europe also suggests climatic changes were responsible for extinctions there, as
11543-495: The middle Pleistocene, southeastern Australia was dominated by browsers, including fauna that consumed C4 plants . By the late Pleistocene, the C4 plant dietary component had decreased considerably. This shift may have been caused by increasingly arid conditions, which may have caused dietary restrictions. Other isotopic analyses of eggshells and wombat teeth also point to a decline of C4 vegetation after 45 Ka. This decline in C4 vegetation
11662-546: The mix of vegetation they need to sustain life and reproduce, within a given area. Increased continentality resulted in reduced and less predictable rainfall limiting the availability of plants necessary for energy and nutrition. It has been suggested that this change in rainfall restricted the amount of time favorable for reproduction. This could disproportionately harm large animals, since they have longer, more inflexible mating periods, and so may have produced young at unfavorable seasons (i.e., when sufficient food, water, or shelter
11781-408: The movement of tectonic plates and volcanoes but glacial cycles and sea level variation have a more significant effect on the vertebrate communities during the Late Pleistocene. The Late Pleistocene was the time when most animals evolved to resemble modern-day animals and they managed to live through the Late mid-Pleistocene since there were no extinction events of megafauna until the end of
11900-569: The north but was unconnected at this time when the main islands of Hokkaido, Honshu , Kyushu and Shikoku were all separate entities. Human migrations happened during this time with people coming in from Eurasia . From about 28 ka, there were migrations across the Bering land bridge from Siberia to Alaska . The people became the Native Americans . It is believed that the original tribes subsequently moved down to Central and South America under pressure from later migrations. In
12019-542: The northern reaches of Russia and Scandinavia to the vast taiga , the boreal coniferous forests which run across the continent. South of the taiga are a belt of temperate broadleaf and mixed forests and temperate coniferous forests . This vast Euro-Siberian region is characterized by many shared plant and animal species, and has many affinities with the temperate and boreal regions of the Nearctic realm of North America . Eurasia and North America were often connected by
12138-538: The onset of the Younger Dryas cooling period, as well as the emergence of the hunter-gatherer Clovis culture . The relative importance of human and climactic factors in the North American extinctions has been the subject of significant controversy. Extinctions totalled around 35 genera. The radiocarbon record for North America south of the Alaska-Yukon region has been described as "inadequate" to construct
12257-630: The palearctic realm; other biogeographers identify the realm boundary as the transition zone between the desert ecoregions and the Mediterranean basin ecoregions to the north, which places the deserts in the Afrotropic, while others place the boundary through the middle of the desert. The Caucasus mountains, which run between the Black Sea and the Caspian Sea , are a particularly rich mix of coniferous, broadleaf, and mixed forests, and include
12376-649: The past 56,000 years indicates that rapid warming events with temperature changes of up to 16 °C (29 °F) had an important impact on the extinction of megafauna. Ancient DNA and radiocarbon data indicates that local genetic populations were replaced by others within the same species or by others within the same genus. Survival of populations was dependent on the existence of refugia and long distance dispersals, which may have been disrupted by human hunters. Other scientists have proposed that increasingly extreme weather—hotter summers and colder winters—referred to as " continentality ", or related changes in rainfall caused
12495-533: The plausibility of this correlation being reflective of causation. The megafaunal extinctions covered a vast period of time and highly variable climatic situations. The earliest extinctions in Australia were complete approximately 50,000 BP, well before the Last Glacial Maximum and before rises in temperature. The most recent extinction in New Zealand was complete no earlier than 500 BP and during
12614-477: The prehistoric overkill hypothesis includes the persistence of megafauna on some islands for millennia past the disappearance of their continental cousins. For instance, ground sloths survived on the Antilles long after North and South American ground sloths were extinct, woolly mammoths died out on remote Wrangel Island 6,000 years after their extinction on the mainland, while Steller's sea cows persisted off
12733-689: The region, but several families are endemic: Calomyscidae ( mouse-like hamsters ), Prolagidae , and Ailuridae ( red pandas ). Several mammal species originated in the Palearctic and spread to the Nearctic during the Ice Age , including the brown bear ( Ursus arctos , known in North America as the grizzly), red deer ( Cervus elaphus ) in Europe and the closely related elk ( Cervus canadensis ) in far eastern Siberia, American bison ( Bison bison ), and reindeer ( Rangifer tarandus , known in North America as
12852-501: The reproductive effort when circumstances once more favored offspring survival. A study looking at the environmental conditions across Europe, Siberia and the Americas from 25,000 to 10,000 YBP found that prolonged warming events leading to deglaciation and maximum rainfall occurred just prior to the transformation of the rangelands that supported megaherbivores into widespread wetlands that supported herbivore-resistant plants. The study proposes that moisture-driven environmental change led to
12971-621: The result of dating errors due to contamination. The extinctions are coincident with the end of the Antarctic Cold Reversal (a cooling period earlier and less severe than the Northern Hemisphere Younger Dryas) and the emergence of Fishtail projectile points , which became widespread across South America. Fishtail projectile points are thought to have been used in big game hunting, though direct evidence of exploitation of extinct megafauna by humans
13090-466: The same; however, the fossil record is limited in the exact chronologies of the extinctions. In general, various reasons have been stated to have caused the extinctions during the Late Pleistocene but the topic is still being debated. Palearctic realm The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of
13209-443: The second-fastest land mammal (after the cheetah ), which may have helped them elude hunters. More difficult to explain in the context of overkill is the survival of bison, since these animals first appeared in North America less than 240,000 years ago and so were geographically removed from human predators for a sizeable period of time. Because ancient bison evolved into living bison, there was no continent-wide extinction of bison at
13328-423: The time could best be described as an overall drying of the landscape due to lower precipitation, resulting in less fresh water availability and more drought conditions. Overall, this led to changes in vegetation, increased fires, overall reduction in grasslands, and a greater competition for already scarce fresh water. These environmental changes proved to be too much for the Australian megafauna to cope with, causing
13447-475: The topic, one supporting climate change, the other supporting human hunting as the primary cause of the extinctions. The hunting hypothesis suggests that humans hunted megaherbivores to extinction, which in turn caused the extinction of carnivores and scavengers which had preyed upon those animals. This hypothesis holds Pleistocene humans responsible for the megafaunal extinction. One variant, known as blitzkrieg , portrays this process as relatively quick. Some of
13566-487: The wave of extinctions in North America is the paleo-American culture associated with the Clovis people ( q.v. ), who were thought to use spear throwers to kill large animals. The chief criticism of the "prehistoric overkill hypothesis" has been that the human population at the time was too small and/or not sufficiently widespread geographically to have been capable of such ecologically significant impacts. This criticism does not mean that climate change scenarios explaining
13685-590: Was being succeeded by the Eemian (Riß-Würm) interglacial period . The Riß-Würm ended 115 ka with the onset of the Last Glacial Period (LGP) which is known in Europe as the Würm (Alpine) or Devensian (Great Britain) or Weichselian glaciation (northern Europe); these are broadly equated with the Wisconsin glaciation (North America), though technically that began much later. The Last Glacial Maximum
13804-537: Was dominated by the cool Last Glacial Period , with temperatures gradually lowering throughout the period, reaching their lowest during the Last Glacial Maximum around 26-20,000 years ago. Most of the world's large ( megafaunal ) animals became extinct during the Late Pleistocene as part of the Late Pleistocene extinctions , a trend that continued into the Holocene. In palaeoanthropology ,
13923-502: Was not much affected by glaciation in the ice ages , and retained 96 percent of Pliocene tree genera, while Europe retained only 27 percent. In the subtropical region of southern China and southern edge of the Himalayas, the Palearctic temperate forests transition to the subtropical and tropical forests of Indomalaya , creating a rich and diverse mix of plant and animal species. The mountains of southwest China are also designated as
14042-709: Was reached during the later millennia of the Würm/Weichselian, estimated between 26 ka and 19 ka when deglaciation began in the Northern Hemisphere. The Würm/Weichselian endured until 16 ka with Northern Europe, including most of Great Britain , covered by an ice sheet. The glaciers reached the Great Lakes in North America. Sea levels fell and two land bridges were temporarily in existence that had significance for human migration : Doggerland , which connected Great Britain to mainland Europe; and
14161-496: Was unavailable because of shifts in the growing season). In contrast, small mammals, with their shorter life cycles , shorter reproductive cycles , and shorter gestation periods, could have adjusted to the increased unpredictability of the climate, both as individuals and as species which allowed them to synchronize their reproductive efforts with conditions favorable for offspring survival. If so, smaller mammals would have lost fewer offspring and would have been better able to repeat
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