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1、MammothReadingAround 11,000 years ago, at the end of the last Ice Age, the mammoth elephants of North America had it pretty good. Food was plentiful, the herds were strong, the climate was favorable. However, something happened and in a short time, all the mammoths disappeared. What happened? These
2、are the three main theories explaining their extinction.The most likely theory involves “man vs. mammoths.” Around 11,000 years ago, the first humans, a group called the Clovis People, came across the land bridge connecting Asia and North America. According to University of Arizona scientist Paul Ma
3、rtin, the Clovis People were clever hunters. They were accompanied by dogs and were armed with spears with sharp stone points. According to Professor Martin, the Clovis People hunted the mammoths to extinction.A second theory is that climatic changes killed off the mammoths. During the Ice Age, huma
4、ns may have found the climate harsh, but it is was perfect for wooly mammoths. The weather seldom changed; it was cold and damp all year round, and there were no seasons. Little by little, however, the climate grew warmer, the glaciers receded, and the moist air became drier. Seasons emerged, plant
5、life changed. Grassy plains became deserts, and the wooly mammoths died of starvation, according to this theory.A third theory, advanced by Ross McPhee of the American Museum of Natural History, is that mammoths were destroyed by diseases brought by humans from the Old World. The microbes were destr
6、oyed by diseases brought by humans from the Old World. The microbes may have been carried by the lice in their hair or by the fleas on their dogs. The mammoths had no resistance. This plague may have passed from mammoth to mammoth and from herd to herd, destroying the species.Listening08,26Listen to
7、 part of a lecture in a geo-science class All right, now were going to continue our discussion of extinction, extinction at the end of the Ice Ages. I gave you a couple of articles to read over the weekend. I d like to talk about. Lets see, lets talk about the wooly mammoth article first. Everyone p
8、ull that one out, okay?Now, the article seems to imply that one of these three theories about the mammoths is probably the right one, but in fact, there are some problems with. Well, with all directly killed off the mammoths by hunting them to death. Sure, it s attempting to blame humans because mam
9、moths were doing just fine until people showed up in North America. But think about this: mammoths were huge, strong, dangerous, wee-armed creatures-look at those tusks! They had thick, thick skin and thick layers of fat-hard to pierce with any spear, no matter how sharp. Why should humans hunt thes
10、e giants when there were other animals around that were smaller, easier to kill? The Clovis People were few in number and they were widely scattered. A computer study shows that they could have eaten only 10% of the mammoths that they supposedly killed. Why would they have killed so many if they wer
11、ent going to eat them?Then, theres the climate-change theory, that mammoths died because it got warmer. The thing is, mammoths endured them just fine. Besides, their relatives in the Old World, the ancestors of the African and Indian elephants, managed to survive this climate change without any problems.So, maybe one of these theories is correct. Maybe a combination of these factors doomed the mammoths, killed them all off. But. Maybe, just maybe, none of these theories is true, and we still dont know the true cause of the mammoths extinction.
