In the nineteenth century north american bison populations were reduced to near extinction for a variety of reasons, all of which are human-related and a result of settler activity in the region. bison population has undergone wide fluctuations in size throughout history; however, human activity, including using bison as a food source, introduction of animal species that competed for habitat, and hunting, all dramatically reduced herd populations.
Early north american settlers and native american indians relied on bison as a food source. nomadic hunters would follow herd movements across the plains and to the rocky mountains where bison grazing trails had been established. it is estimated that 20 to 30 million bison once dominated the north american landscape and it was in part this gigantic population that led many people to believe that bison was an inexhaustible and limitless supply of food. as the settlers moved west, over-consumption of the bison reduced bison populations to less than 2,000 before the turn of the nineteenth century.
During the american civil war period, humans introduced many other grazing species that directly competed with bison for habitat and food resources. these species included cattle and horses which forced bison into smaller and smaller pockets of habitat. this had the result of bison directly competing with each other for food. under these circumstances, it is no wonder bison populations were quickly decimated.
Technological developments in the accuracy and range of rifles also had a considerable impact on bison herd populations. the new rifles allowed for increased accuracy from increased distances so that the slaughter of bison became easier and easier. the increased mortality of these new rifles, coupled with the fact that many people took up bison hunting for sport, pushed bison to the brink of complete annihilation.
综合写作听力音频：
Question:
Summarize the points made in the lecture you just heard, explaining how they cast doubt on the specific theories discussed in the reading passage.
As I mentioned in class, governments make public policies to describe their responses to various problems that affect a community. Part of this process involves setting and defending priorities about which issues deserve the most attention and resources. For example, governments need to decide whether they should spend more money on education or on environmental protections. If you were a policy maker, which issue would you argue is more important—education or environmental protections? Why?
Kelly的观点：
We all live on planet Earth, and it is the only planet we have. Therefore, we must take care of it. Clearly, protecting the environment should be the government’s priority over education. I think the REAL question is, which approach to protecting the environment —restricting pollution, regulating population, promoting clean energy, or something else—should be the government’s priority
Andrew的观点：
I disagree with Kelly that that the environment is more important than education.
Education is actually the best way to protect the environment. Educated people can see
how their decisions affect the world around them. Also, with better science and
technology education, we can develop solutions to environmental problems. Therefore,
I think the government should spend more money on education.
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