12月GMAT阅读机经:动物灭绝.

　　GMAT逻辑机经能够指引人们在阅读的道路上不再迷茫，这不12月GMAT阅读机经就来为你指明道路，澳际小编就在这寒冬中为大家吹来一股GMAT机经的暖风，为大家分享GMAT阅读机经，希望大家能感受到这股暖意，并把它化为能量，在GMAT考试的道路上勇往直前。

　　巨型动物megafauna灭绝的，好像亚洲非洲没灭，因为它们慢慢适应了捕猎的人，但是其他地方都灭光了，因为人类突然出现，很长，没仔细看，也是乱选的。

　　【考古】

　　【版本1】

　　第一段：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)

　　第二段：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。

　　第三段：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)。

　　【版本2】

　　第一段：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)

　　第二段，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...

　　【版本3】

　　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。

　　【版本4】

　　说一种大型动物的灭绝问题。

　　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。

　　【版本5】

　　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。

　　【背景资料】

　　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 rerred 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 rerred 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 bore the last glacial maximum and bore 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 bore extinction.

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