下面是出国留学网GMAT频道提供的2015年7月GMAT阅读机经之物种灭绝，欢迎阅读。
点击进入：2015年7月GMAT阅读机经汇总
物种灭绝(已考古/待确认)
本月原始：
[v1]
一篇是讲物种灭绝的，但是不是JJ上那一个。
第一段：是说这个物种在哪段时间各个地区各减少了多少，有一堆百分比。然后说减少的速度和什么东西correlates了(这里有题，问那个不认识的词是指什么)。所以作者猜测这个物种的灭绝和人类hunting有关系。
第二段：说有人说这个生物灭绝是因为climate的变化。然后说可是climate变化导致某种whale灭绝的同时其他生物数量也减少。而这种生物灭绝时却不是这样。(这里有题，好像是问为什么climate不是导致这个生物灭绝的原因)
最后： 又有人说可是找到的化石很少有人能说明那个时期的人靠打猎为生，然后作者回应说，虽然打猎的化石少，但是完全没有找到化石说他们靠采集为生。(这里有题，作者这样说这个化石是什么意思)
后面好像记不清了。。卤煮自己的语言讲一下：又有人question说这个动物很大，现在的科学技术要打猎他都比较困难，古代那些人不怕它吗。然后作者说这个动物，还是这些土著以前能过survive下来可能就是因为它们成功地防御了袭击。。。(这边有题考的)，无奈时间仓促，文章又长，卤煮没怎么看懂，大家考到认真看看最后几句。
考古：
V1.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。
V2.是讲大动物灭绝的，不过不是灭绝原因，是讲生态学家们想要在北美引进曾在P时代灭绝的大动物们(如猛犸象等等)，说现在的北美洲有它们的后代。讲了引进大动物的好处(举了一些引进别的动物如狮子、老虎、狼之类的)，好像可以保持生物链平衡或者生态平衡。最后一段说有人反对这个提议，说了两个反对点，都被作者一一反驳了。
V3. 第三篇是No.7-动物灭绝。一共有三段。
P1：科学家们普遍接受陨星撞击地球导致恐龙灭绝的观点，这个被称作K-Tevent。有一系列证据能够证明这个观点。包括1.那个时代的sediment中包含某种地球上不常见但常见于外太空的物质;2.某种in的东东dusted 在地表(这里有细节题，问说关于撞击地球的陨石，可以推断出什么，我选了陨石中含有大量这种in的东东，不确定，但是其他选项好像也都不太对，大家到时再仔细看看);3.sediment中含有某种东西，这种东西是由于植物大量快速死亡产生的，因此能够证明这个时代有植物突然灭绝。
P2：科学家们也曾猜想过陨星撞击地球也导致了某些其他物种灭亡。但是证据表明其他物种是陆续灭亡的，不像是陨星撞击地球产生的结果。
P3：火山爆发可能是导致这些物种灭亡的一些原因。然后就讲了火山爆发释放某种有毒物质，这种有毒物质慢慢渗透蔓延，导致各种植物灭亡。
V4. 第一段主要讲现在大多数科学家相信大型动物,如恐龙消失是由于损石撞击的原因,接着讲了很多关于asteriod 的东西,及释放很多Iradium 什么的有考点,但是植物是由于什么原因(有考点) 有一个问题是问第一句话作用的,第一句说就是说大多数科学家相信大型动物怎么样的,第二段有人说asteriod 也导致了其他的一些动物消失,但是这个结论不成立, 举了很多不成立的原因.第二段说其他的动物消失是由于后来的火山活动造成的,总之这个结论是成立的.
V5. 另一篇是物种灭绝，不过与JJ里的不一样貌似变体，说一下：
第一段：K-T陨石碰撞事件引起了恐龙灭绝，证据是有大量地球上没有的i元素。另外有两个分别关于突然灭绝的证据：动物的证据是fossil;植物的证据是碳的同位素剧增。
第二段：K-T事件不能解释其他种类的灭绝。举了另外两个时期的例子。说如果其他种类的灭绝也是行星碰撞引起的，则需要有多次行星与地球碰撞的事件发生，这在其他种类灭绝的时间范围内是不大可能的。第三段：其他种类灭绝的原因是火山爆发。岩浆流到水里，阻挡更多氧气进入，造成厌氧细菌大量繁殖。释放出的硫有毒物毒死了很多物种。导致了其他种类的灭绝。其实就是说陨石碰撞造成恐龙灭绝，火山爆发造成其他种类的灭绝。By tcpwt
问题：
1.这篇的第一道题目是问第一段第一句话的用意是什么(就是“科学家们普遍接受陨星撞击地球导致恐龙灭绝的观点，这个被称作E-T event”那句)?选项有a.说明其实恐龙不是灭绝于陨星撞击;b.提出了一个后面两段都在反对的观点。C.提出了全文的中心论点。我觉得好像都不大对啊，就很囧地选了最后一项：说明E-T event是如何导致恐龙灭绝的。
V6：关于生物灭绝的，大概就是一个远古时期的恐龙灭绝了，有科学家说是因为陨石坠落造成气候变化，但第二段反驳说气候变化范围太大，而有些对气候敏感的动物并未灭绝，接着说可能是因为植物的大规模灭绝导致的，找到一些证据，最后一段不记得了。
V7.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)。
V8.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...
V9.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。
V10.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>.
V11.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。
【参考文献】
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.