单选题 18.From enlargements that are commonly found on the ulna bones of the forearms of Ice Age human skeletons, anthropologists have drawn the conclusion that the Ice Age humans represented by those skeletons frequently hunted by throwing spears. The bone enlargements, the anthropologists believe, resulted from the stresses of habitual throwing.
Which of the following, if true, would be the LEAST appropriate to use as support for the conclusion drawn by the anthropologists?

A、 Humans typically favor one arm over the other when throwing, and most Ice Age human skeletons have enlargements on the ulna bone of only one arm.
B、 Such enlargements on the ulna bone do not appear on skeletons from other human cultures of the same time period whose diets are believed to have been mainly vegetarian.
C、 Cave paintings dating from approximately the same time period and located not far from where the skeletons were found show hunters carrying and throwing spears.
D、 Damaged bones in the skeletons show evidence of diseases that are believed to have afflicted most people living during the Ice Age.
E、 Twentieth-century athletes who use a throwing motion similar to that of a hunter throwing a spear often develop enlargements on the ulna bone similar to those detected on the Ice Age skeletons.

【正确答案】 D

【答案解析】Evaluation of a Plan
Situation The ulna-bone enlargements often found on forearms of skeletons of Ice Age humans have led anthropologists to conclude that those humans frequently hunted by throwing spears and that this practice caused the bone enlargement.
Reasoning Which of the additional pieces of information offered provide the weakest (if any) support for the anthropologists' conclusion? A. premise of the anthropologists' reasoning is that many Ice Age humans developed enlarged ulna bones. Another premise is that the bone enlargements resulted from the stresses of habitual [spear] throwing. The anthropologists' conclusion is that those Ice Age humans frequently hunted by throwing spears. Several of the five additional pieces of information provide additional support for the anthropologists' conclusion.
A The information, if true, that the bone enlargement found on Ice Age skeletons is typically found on just one arm provides significant additional support for the argument's conclusion. Ice Age spear-throwing hunters would likely have been left-handed or right-handed and would have habitually used just one of their arms—either left or right—to throw spears.
B This information, if true, provides significant additional support for the anthropologists' conclusion. Ice Age humans with mainly vegetarian diets would have hunted, if at all, only infrequently—and so would not have been habitual spear-throwing hunters. We would expect, then, that if the anthropologists' conclusion is correct, enlarged ulna bones would not be found among the remains of such populations— and that is what the archaeological evidence indicates.
C This information, if true, provides compelling evidence that some Ice Age human populations hunted using spears, and so it provides significant additional support for the anthropologists' conclusion.
D Correct. This information, if true, tends to weaken the support for the anthropologists' conclusion. It vaguely suggests that diseases that were endemic in the Ice Age and caused bone damage might adequately explain the enlargement of ulna bones found in the archaeological evidence. If this were correct, then that bone enlargement could no longer be regarded as compelling evidence of spear-throwing.
E This information, if true, provides additional support for the anthropologists' conclusion. Twentieth-century athletes (perhaps javelin throwers, for example) use a throwing motion like that of spear throwers, and they often develop enlarged ulna bones like those found in the archaeological evidence.
The correct answer is D.