A recent study has provided clues to predator-prey dynamics in the late Pleistocene era. Researchers compared the number of tooth fractures in present-day carnivores with tooth fractures in carnivores that lived 36,000 to 10,000 years ago and that were preserved in the Rancho La Brea tar pits in Los Angeles. The breakage frequencies in the extinct species were strikingly higher than those in the present-day species.

In considering possible explanations for this finding, the researchers dismissed demographic bias because older individuals were not overrepresented in the fossil samples. They rejected preservational bias because a total absence of breakage in two extinct species demonstrated that the fractures were not the result of abrasion within the pits. They ruled out local bias because breakage data obtained from other Pleistocene sites were similar to the La Brea data. The explanation they consider most plausible is behavioral differences between extinct and present-day carnivores—in particular, more contact between the teeth of predators and the bones of prey due to more thorough consumption of carcasses by the extinct species. Such thorough carcass consumption implies to the researchers either that prey availability was low, at least seasonally, or that there was intense competition over kills and a high rate of carcass theft due to relatively high predator densities.


The primary purpose of the passage is to


present several explanations for a well-known fact

suggest alternative methods for resolving a debate

argue in favor of a controversial theory

question the methodology used in a study

discuss the implications of a research finding

考题讲解

题目分析:

题目释义:

主旨题目

考点:

主旨(Main idea)  

旨在考察我们对文章整体的把握程度,对文章的结构的分析能力和把控能力,以及对作者逻辑的判断。

这篇文章作者是想说明自己对一个发现的看法。主题十分突出。



选项分析:

A选项:展示出对于一个众所周知的事实的几个解释。首先,即便是第一段的研究发现可以算作是一个“众所周知的事实”,作者的目的也不是展示那几个“bias”。

B选项:提出解决一个争论的其他方法。这个选项比较有迷惑性。作者确实是想提出一个自己的原因来解读一个“发现”。但是作者不是要说明怎么解决这些“bais”的方法。而是提出自己对一个研究发现的解读。

C选项:支持一个有争议的原理。作者并没有支持哪个原理,而是提出自己对一个问题的解读。

D选项:
质疑在一个在研究中应用的方法。文中没有提到研究中应用了什么方法。这个选项属于无中生有。

E选项:
Correct. 讨论一个研究发现的含义。作者的目的是驳斥其他的对与这项发现的解读而提出自己对这项发现的解释。

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