15.magafuana extinction– 4.10 JJ

　　考古版

　　V1：P1：讲非洲和什么洲的什么猛兽只有20%-30%(数字不确定)再A时期灭绝，澳大利亚和什么洲的同样大型猛兽七八十吧(数字不确定，但是比前面大很多)在B时期(比A晚很多年)灭绝。作者认为是因为在A时期猛兽有时间去适应人类逐渐变强变得可以消灭他们。而B时期，人类能力已经很强了。

　　P2：不太记得了，大概是继续证明上述观点吧。好像是有人说是因为是天气原因，然后作者举例两个相近的地方，如果是因为天气原因，那么这两个地方的猛兽应该都在同样的时间消失，但是事实不是这样。所以作者继续坚持自己的观点。

　　P3：给了两个反对作者观点的意见。第一个ms是和植物灭绝有什么关系，但是作者认为虽然和动物灭绝滴证据很少(little之类的词修饰的吧)，但是整个就没有(记得作者用的是no)和植物灭绝有关的evidence。第二个是什么忘记了，作者就是又反驳了这个观点。总之，作者就是坚持自己的观点。

　　V2：讨论亚洲，非洲，澳洲还有m什么地方的大型动物(?)在不同时期大量灭绝的问题。第一段提出一个是人类把这些动物都给干了，但是非洲和亚洲这些动物灭绝的少一些，其他地方挺多的(这儿有个细节忘了，有题——为什么亚洲和非洲的少，我选的这儿的人养殖还是耕种什么的，忘了)二，三段又说神马人反对，说是可能由于气候原因还有什么的(题——如果是气候原因会发生什么)，然后作者说如果是气候原因的话应该XX地和YY地的大型动物同时灭据，但事实上没有，反正都被作者给驳倒了。

　　主旨题：main purpose好像是一个theory并支持它。

　　V3：大型动物的灭绝和人类的捕猎有关，然后提出了很多论据证明这一观点。最后一点驳斥了他人的反对意见：一，大型动物灭绝是气候所致;二人类的捕猎技术不能达到比如补杀野牛得水平

　　V4：P1：就是说非洲，亚洲等等人类迁移较早的地区，动物在一个较早的时期内灭绝的较少，15%左右(数据比较确定，但是不考)。。。然后澳洲、美洲等等人类取得较玩的地方在较晚的时候反而大规模灭绝80-95%左右(数字依然比较确定然后依旧不考)。然后就说这是因为亚非等等的动物AND人类一起生活，慢慢人类的进步，比如狩猎工具的进步，然后比较有时间去慢慢适应，然后那些人类较晚的因为过去很少有人而且人类更加发达，然后就大规模灭绝。(有题，文章主旨，以及作者的对这个大灭绝原因的同意)。顺便说下，那个人类较早迁徙和较晚迁徙文章中没有直接提到，但这基本是个常识，也为了同学们理解方便就顺便补上了。

　　P2： 将有人提出可能是气候原因，然后作者反驳，说如果是气候原因那为神马美洲(还是非洲?)周围的群岛以及澳洲AND澳洲周围的新西兰的大型猛兽没有同时灭绝。。。。然后这里有题问如果是气候原因应该是怎么样?

　　P3：也是反驳另一种理论，但是不考，可以忽略。意思也大概说下，就是有些人说猛兽灭绝的化石证据不足，但是作者说已经很充足了，如果和植物的化石一比，意思植物化石很少很少。总之就是为了证明是人类还有猛兽的适应性等等。

　　V5：作者观点：猛兽灭绝跟人类有关

　　P1：讲了三个地方，第一个地方在60000年灭绝了15%，第二个地方在40000年前灭绝了80%。第三个地方blabla。然后讲原因，因为第一个地方的动物适应了人类的捕猎，而第二个地方的人类来的太快，没动物没来的及适应(问题：为什么第一个地方比第二个地方灭绝的百分比小?)

　　P2：讲灭绝不会是因为气候引起的，如果是气候原因，A地和B地距离很近，但是动物灭绝时间却不一样。(问题：如果是气候引起的灭绝，会怎么样?)

　　P3：又提出别人的两种观点，作者又一一反驳。第二个观点处有题，我想不起来了。。。

　　V6：M灭绝那个，狗狗里面有~~就是第一段讲是人们造成的，举了一些例子~~

　　第二段讲是气候造成的，但是后来被否定了，因为临近几个地方的其他动物什么的都没灭绝，这里举了两个例子，都是和地理位置靠的近什么(后面的网了，看看以前的吧)

　　我想说文章真的很熟悉，可是题目满陌生的，但是也不是很难，我也想不起来了~~~

　　gwd里阅读的变体。嗯!以下是找到的原文了!

　　Martin (1968, 1984, 1990) has summarized the evidence for the world-wide

　　extinction of late Pleistocene megafauna.

　　In Africa and Asia 15–20 percent of the genera disappeared 80–60,000 years B.P.; in Australia 94 percent were lost from 40–15,000 years B.P.; North and South America

　　experienced a 70–80 percent loss in the last 15,000 years, with an abrupt North American loss of mammoth, mastodon, ground sloth, and such dependent predators and scavengers as the saber toothed cat and (in much of its range) the condor 11,000 years ago. The horse and two subspecies of bison were gone by 9–8,000 years ago. This worldwide pattern correlates suspiciously with the chronology of human colonization leading to Paul Martin's hypothesis that extinction was directly or indirectly due to “overkill” by exceptionally competent hunter cultures. This model explains the light extinctions in Africa and Asia where modern humankind “grew up,” allowing gradual adaptation to humankind's accumulating proficiency as a super predator; it explains the abrupt massive losses in Australia and the Americas—the only habitable continents that were colonized suddenly by advanced stone-aged humans. But the control cases for Martin's “experiment” are the large oceanic islands such as Madagascar and New Zealand; both were colonized within the last 1000 years, and both suffered a wave of extinctions at this time.One wonders, if extinction was due to climatic change, why Madagascar extinctions were not coincident with those of Africa 220 miles off its coast, and those of Australia were not coincident with New Zealand extinctions; and why European and Ukrainian mammoths became extinct 13,000 years B.P. while in North America they survived another 2000 years. Previous great extinction waves had affected plants and small animals as well as large animals, but the late Pleistocene extinctions are concentrated on the large gregarious herding, or slow moving, animals—the ideal prey of human hunters. Such large genera are also the animals that are slower growing, have longer gestation periods, require longer periods of maternal care, and live longer. Consequently they were more vulnerable to hunting pressure because reductions in biomass require more time to recover. The theory is bold—some say fanciful.

　　古中古

　　V1：P1：一个是maya(某种动物)的灭绝是因为人类的殖民发展，它在亚洲和非洲可能会上升..和美洲想比 balabal之类(我认为作者是认同这个观点的)

　　P2：说一个反对观点是因为天气，接着举例排除了这个可能性...另一个反对观点说是因为maya没有存活技能，后来通过fossil又排除了这个观点..这个考了两个文章结构题..还有举例说作者会同意下面那一项...

　　V2：还有个阅读，讲M动物在P时代灭绝。跟JJ一样。很简单。题目基本都忘记了。但是大家都应该能把这阅读的题都作对。

　　问题：1.问「 If hunting evidence are small, then the collecting evidence is nonexistent.」这句话被作者拿来做什么用?

　　我选「不能用来作为反驳「人类活动造成m动物灭绝」这个理论的理由」

　　2.问作者对第二个counterargument(即人类狩猎技术不够好)的反驳暗指下列哪件事?

　　我选「更新世动物的防御能力较现存动物低」

　　#第二个counterargument是说古时候人类狩猎技巧不高明，所以应该很难将m动物的灭绝归因于人类。但是作者驳斥说，并不需要高超的狩猎用具(用于捕捉现在的大型动物，如大象)就可以捕捉到m动物，因为m动物的防御能力并不如现在的大象等，所以自然也不需要高超的狩猎工具。

　　V3：说一种大型动物的灭绝问题。三段：第一段，先说了他们分别在几个洲灭绝的时间和percent。然后结论是因为人类的捕猎。第二段，说是不是天气原因呢。举了例子说不是，如果是也会影响小动物和植物。这里有考题，说作者用什么论点推翻这个假设的。第三段，有人说化石里面没有证据，作者就说如果这个证据很少，别的更没证据。反正作者就是认准了是human hunter。讨论了为什么在亚洲和非洲减少的比较慢，早期时候，我答的是因为那时候人类发展慢，动物有时间适应，美洲都是直接拿枪去殖民的。第一段有，可以确认下。

　　V4：第二篇是说大型动物M(貌似是猛犸象吧～)的灭绝原因，基本上作者就是先描述一下灭绝的时间和情况然后说不知道是人类原因还是气候原因，中间是排除气候原因，然后说就是人类HUNTING造成的。也不难。有一个题目说解释一个曾经发生的“lighter extinction”，文中说的是当时人们也处于捕猎技术成长的阶段，那些动物就有时间去适应，答案就是这个意思的一个改写

　　V5：史前(P开头的那个单词)大动物(M开头单词)灭绝理论 Quaternary extinction event

　　(1)P时期大动物灭绝很快，最早在亚非，接着到澳洲和美洲(都有具体年份说明的，比如15000年前)，好奇怪。为什么呢?学者A说是因为人类活动。因为这些时间都对应着相应地区的人类频繁活动。为了进一步说明，A还说一：灭绝的都是那种又大又笨的，容易被人抓到，二：亚非的大动物灭绝的不如澳美的 drastically，是因为人类是突然到澳美洲的，大动物都来不及反应。(有题问道亚非动物灭绝的为什么比澳美缓慢)

　　(2)顺承上文，继续支持A(没有问道问题，没记得很多)不过有说道，历史上如果由CLIMATE造成的物种灭绝都是更大范围，而且大物种，小物种一起灭绝的，但这个P时段的灭绝只涉及大物种，所以还是认为还是人类干涉而不是气候。

　　(3)但是这个解释又两个counterargument，(但最后还是被作者反对掉了，说明作者是支持A的)counterargument一：根据fossil，P时代人类主要靠collect植物什么的过活，化石没有反映出人类hunting，作者反对，提出一句话：if hunting evidences are "small", then the collecting evidence are nonexistent. (这句话有考题，但有点忘了);counterargument二：在那个时代人类捕猎水平不够，根本不可能造成那么多物种灭绝，说道要用rifle之类的才能造成，另外还说到，大动物如果被捕猎死的话，死相会有挣扎的痕迹，但是没有。最后作者还是把这个反对了下(没仔细看了)。720 (M50 V37)

　　相关文章，背景知识　　Pleistocene megafauna 更新世动物

　　In broad usage, the Holocene extinction event includes the notable disappearance of large mammals, known as megafauna, by the end of the last glacial period 9,000 to 13,000 years ago. Such disappearances have been considered as either a response to climate change, a result of the proliferation of modern humans, or both. These extinctions, occurring near the Pleistocene–Holocene boundary, are sometimes referred to as the Quaternary extinction event or Ice Age extinction event. However the Holocene extinction event continues through the events of the past several millennia and includes the present time.

　　These species appear to have died off as humans expanded out of Africa and Eurasia, the only continents that still retain a diversity of megafauna comparable to what was lost. Three theories have been given for these extinctions: hunting by the spreading humans, climatic change, and spreading disease. A combination of those explanations is also possible.

　　Human Hunting

　　This hypothesis was proposed 40 years ago by Paul S. Martin。This theory holds Pleistocene humans responsible for the megafaunal extinction. One variant, often referred to as overkill, portrays humans as hunting the megafauna to extinction within a relatively short period of time. Some of the direct evidence for this includes: fossils of megafauna found in conjunction with human remains, embedded arrows and tool cut marks found in megafaunal bones, and 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, the Americas, Madagascar and New Zealand, areas where early humans were non-existent. Based on this evidence, a picture arises of the megafauna of Asia and Africa evolving with humans, learning to be wary of them, and in other parts of the world the wildlife appearing ecologically naive and easier to hunt. This is particularly true of island fauna, which display a dangerous lack of fear of humans.

　　The most convincing evidence of his theory is that 80% of the North American large mammal species disappeared within 1000 years of the arrival of humans on the Western Hemisphere continents. World wide extinctions seem to follow the migration of humans and to be most severe where humans arrived most recently and least severe where humans were originally – Africa (see figure at right). This suggests that in Africa, where humans evolved, prey animals and human hunting ability evolved together, so the animals evolved avoidance techniques. As humans migrated throughout the world and became more and more proficient at hunting, they encountered animals that had evolved without the presence of humans. Lacking the fear of humans that African animals had developed, animals outside of Africa were easy prey for human hunting techniques. It also suggests that this is independent of climate change

　　Circumstantially, the close correlation in time between the appearance of humans in an area and extinction there provides weight to this theory. This is perhaps the strongest evidence, as it is almost impossible that it could be coincidental when science has so many data points. For example, the woolly mammoth survived on islands despite worsening climatic conditions for thousands of years after the end of the last glaciation, but they died out when humans arrived around 1700 BC. The megafaunal extinctions covered a vast period of time and highly variable climatic situations. The earliest extinctions in Australia were complete approximately 30,000 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 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.

　　Climate Change

　　The size of a short faced bear compared with a human.An alternative explanation offered by many scientists is that the extinctions were caused by climatic change following the last Ice Age. Critics object that since there were multiple Ice Ages in the evolutionary history of many of the megafauna, it is rather implausible that only after the last glacial would there be such extinctions.

　　Some evidence weighs against this theory as applied to Australia. It has been shown that the prevailing climate at the time of extinction (40,000–50,000 BP) was similar to that of today, and that the extinct animals were strongly adapted to an arid climate. The evidence indicates that all of the extinctions took place in the same short time period, which was the time when humans entered the landscape. The main mechanism for extinction was likely fire (started by humans) in a then much less fire-adapted landscape. Isotopic evidence shows sudden changes in the diet of surviving species, which could correspond to the stress they experienced before extinction