请教OG12第二篇阅读，第7题

candybecky

原文是：the researchers dismissed demographic bias because older individuals were not overrepresented in the fossil samples.

第7题是：

The researchers’ conclusion concerning the absence demographic bias would be most seriously undermined if it were found that

(A) the older an individual carnivore is, the more likely it is to have a large number of tooth fractures

(B) the average age at death of a present-day carnivore is greater than was the average age at death of a Pleistocene carnivore

(C) in Pleistocene carnivore species, older individuals consumed carcasses as thoroughly as did younger individuals

(D) the methods used to determine animals’ ages in fossil samples tend to misidentify many older individuals as younger individuals

(E) data concerning the ages of fossil samples cannot provide reliable information about behavioral differences between extinct carnivores and present-day carnivores


我不明白的是C选项，为什么不对？


OG的解释更离谱，之前明明说：older individuals were not overrepresented in the fossil samples. This implies that older carnivores would be expected to have more tooth fractures than younger ones.

看，它提到了older 什么什么than younger
结果到了C的解释，却说：The comparison between older and younger individuals is irrelevant to the researchers' conclusion.

这是什么意思啊？？

The comparison between older and younger individuals is irrelevant to the researchers' conclusion.

这是什么意思啊？？

candybecky

bias就是认为older应该比young更多，那么C说两者一样不就是undermine了吗

ashleych

我覺得樓主是理解錯了題目

首先文章中說一個研究發現滅絕的物種比現存物種有更多的牙齒破碎，研究

者們首先排除了年齡結構的因素，因為認為遠古的動物并不比現在的動物有

更多的老齡人口（作者默認了老了的動物會有更多的牙齒破損，因此如果遠

古動物比現在的動物老齡化的話，就不能排除年齡結構的因素了）

第7題題目問的是，如果下面哪個選項被發現的話，研究者排除年齡結構這

一推測會被Undermined
正確答案D的意思是研究者根據化石確定滅絕動物年齡的做法是錯誤的，把

某些老年動物誤當做了年輕動物。這個錯誤導致了老年動物沒有

overrepresent, 實際上卻發生了overrepresent 的情況，因此demographic

bias 就會被undermined

C選項的意思是老年動物和年輕動物consumed carcasses 的程度相同。這和

demographic bias 沒有關係
樓主是不是過度推理了，認為如果老年動物和年輕動物condumed carcasses

的程度相同，他們就會有相同的tooth fraction, 但即使這樣，仔細想想，

會認為滅絕動物應該比現存的動物有更少的tooth fraction. 當然這已經扯

遠了。
至於文章爲什麽會默認老年動物會比年輕動物有更多的牙齒破損，我認為把

原文的那句話多讀幾遍就應該會感受到作者的意思。另外即使C成立，即兩

者有相同的carcasses consumption 也和作者默認的老年動物比年輕動物有

更多的牙齒破損不矛盾，因為有其他很多因素（如自然衰老）等因素影響著

牙齒情況。當然，文章沒提這些，我又扯遠了……

candybecky

楼上的解释的太好了！ 谢谢！

debbiebeansky

解释的真好，这样清晰的解释。。。cd不多见，如果所有问题都有一针见血地道的解释，很多人能少走弯路当然个人认为还是有点不全对。作者排除的第一个是统计学上出错的可能性，是排除当older individuals 是不是在比较的过程中样本过多导致得出OI breakage frequency高于present-day individuals的结论的。这里文章说已经排除了OI overrepresented in the samples。og中该选项的解释也很明确。

psychepsyche

The key of here is the underlying hypothesis that older carnivors had comsumed more carcasses in their lives than  had the younger and more comsumption caused more fraction.
The C option is just a part of this hypothesis and of course a wrong option.
However, the hypothesis  is not explicit in the passage but can be reached in mind through the reading process.
I think LZ didn't understand the constrcture here rather than over-reasoninged the question.