問題詳情

四、閱讀測驗：請依文意選出一個最適合的答案，每題 2 分，共 10 分。  Although humans have much bigger brains relative to body weight than do other primates, the total resting energyrequirements of the human body are no greater than those of any other mammal of the same size, implying that we use a highershare of our daily energy budget to feed our voracious brains. How did such an energetically costly brain evolve?  One theory holds that bipedalism enabled hominids to cool their cranial blood, thereby freezing the heat-sensitive brain ofthe temperature constraints that had kept its size in check. But brain expansion almost certainly could not have occurred untilhominids adopted a diet sufficiently rich in calories and nutrients to meet the associated costs. Across all primates, species withbigger brains dine on richer foods, and humans are the extreme example of this correlation, boasting the largest relative brain sizeand the choicest diet. Animal foods are far denser in calories and nutrients than most plant foods, and so it stands to reason thatfor early Homo, acquiring more gray matter meant seeking out more of the energy-dense fare. Fossils, too, indicate that improvements to dietary quality accompanied evolutionary brain growth. The later, robust protohumans— a dead-end branch of the human family tree that lived alongside members of our own genus had heavily builtmandibles and huge, thickly enameled molar teeth built for processing tough, low-quality plant foods, while early members ofthe genus Homo, which descended from the gracile proto-humans, had much more delicate jaws and, smaller molars, despitebeing far larger in terms of overall body size than their predecessors.Environmental change appears to have set the stage for this evolutionary change when the continued desiccation of theAfrican landscape limited the amount and variety of edible plant foods available to hominids. Thus, we often see an increase inanimal bones at hominid sites during this period, along with evidence that these beasts were butchered using stone tools. Whilethe robust proto-humans coped with this problem morphologically, evolving anatomical specializations that enabled them tosubsist on more widely available, difficult-to-chew foods, Homo took a different path. As it turns out, the spread of grasslandsalso led to an increase in the relative abundance of foraging mammals such as antelope and gazelle, creating opportunities forhominids capable of exploiting them. Homo developed the first hunting-and-gathering economy in which game animals becamea significant part of the diet and resources were shared among members of the foraging groups.  These changes in diet and foraging behavior did not turn our ancestors into strict carnivores, but the addition of modestamounts of animals foods to the menu, combined with the sharing of resources that is typical of hunter-gatherer groups,significantly increased the quality and stability of hominid diets, and after the initial spurt in brain growth, diet and brainexpansion probably interacted synergistically: bigger brains produced more complex social behavior, which led to further shiftsin foraging tactics and improved diet, which in turn fostered additional brain evolution.
46. The author is primarily concerned with ________.
(A) contrasting the characteristics of Homo and his primate ancestors
(B) analyzing the evolutionary basis for the development of the modern human diet
(C) disproving the view that bipedalism alone can account for the human brain’s evolution
(D) describing a relationship between the acquisition of an improved diet and the development of the human brain
(E) demonstrating the importance of brain growth in developing human social behavior, foraging tactics and better diet.

參考答案

答案：D
難度：簡單0.714286
統計：A(1),B(1),C(1),D(10),E(1)

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