填空题
Mastering the Race

A If asked to identify the single most important physical attribute that marks mankind from the beasts, the ability to run for long distances without falling over would probably trail last, long after an expanded brain, dexterous hands, the existence of childhood or even just standing upright. Yet according to a report in today's Nature, it is endurance running—as distinct from sprinting, walking or just standing up—that explains many of the peculiarities of the human frame.
B Most of the explanations of the origins and evolution of bipeds have concentrated on our ability to walk. But humans have two gaits, walking and running, and in discussions of evolution, running gets left behind. Why? The easy answer is the proverbial one, that we had to learn to walk before we could run. This does not really explain anything, and in any case there's more to it than that, according to Dennis M. Bramble of the University of Utah, and Daniel E. Lieberman of Harvard University.
C Scientists have not looked at the evolution of running, because in the world of animal athleticism humans are seen as very poor runners. Or are they? As every Olympian will know, there is more than one kind of running. But usually when we think of running, it is running fast over short distances. Sprinting demands specialist training. Few humans make good sprinters and even an Olympian can't keep up the pace of a 100-metre dash for more than 15 seconds or so. Which is, in the scheme of things, pathetic. Horses, antelope, and greyhounds can gallop twice as fast for several minutes without conspicuous distress.
D Sustained running, however, is a different game, and something we are surprisingly successful at. With a little training, we can maintain a steady pace for miles at a time and our speeds compare not too unfavourably with those of horses and dogs. Although four-legged animals easily outpace us in a sprint, this is partly a function of having four legs, in that quadrupeds can gallop, a fore-and-aft gait that is physically impossible for an animal with two legs, one on each side. But trotting is a contralateral gait directly comparable with human running, and a human can keep up with a trotting pony. If this sounds incredible as you charge down the street after a fast-disappearing bus, consider this: long-distance running may be common among animals such as dogs and horses, but extremely rare in primates—so rare, in fact, that humans are the only primates to do it. To be sure, chimps may be nifty sprinters, but they are lousy joggers.
E All this, say Bramble and Lieberman, demands explanation. So they point to a number of features of the human frame that seem particularly good adaptations for running, as distinct from just walking. Our long legs with compact, strongly-arched feet, pulled together with long tendons that store energy, ensure a bouncy, efficient trot. Less obvious is the fact that our bodies are constructed so that our arms can swing freely, out of phase with our moving feet, keeping us balanced as we run'. Our forearms are proportionally shorter and lighter than in other primates—an advantage given that we keep them habitually flexed as we run. We have a ligament in our necks that ensures our heads are maintained in an upwards and forwards direction, towards the finish line. An equivalent ligament is found in horses but not, crucially, in chimpanzees.
F Questions of cause and effect in evolution are notoriously tricky, as they so often go no further than "just-so" stories that cannot be tested or falsified. Scenarios abound explaining what made humans stand upright: to free hands for carrying food, making tools or cuddling babies; to expose a greater area of (increasingly hairless) skin to cooling breezes; simply to see over the long grass, and so on. All are possible, but none can be tested rigorously. In any case, none can explain adaptations that seem to make sense only in the context of endurance running. To explain these, we have to invoke scenarios that are equally unfalsifiable.
G One interesting idea comes from studying animals that also go in for endurance running—open country pursuit-predators and scavengers such as dogs and hyenas. A suitable frame for long-distance running emerged with the genus Homo around 2.5 million years ago, along with big brains, small guts and small teeth—all traits consistent with a carnivorous lifestyle and a diet rich in fats and proteins. Before we invented bows and arrows to bridge that gap, if we wanted to bring meat home, we had to run for it.
Questions 1-6
Reading Passage 1 has seven paragraphs A-G.
Choose the most suitable headings for paragraphs B-G from the list of headings given.
Write the correct numbers, in boxes 1-6 on your answer sheet.
List of Headings

i A key difference between humans and animals
ii Good balance when running
iii Looking for evolutionary reasons
iv Using weapons to kill animals for food
v Relatively weak performance as sprinters
vi Hunting by chasing animals over long distances
vii Why we are well built for distance running
viii Two different ways of going on foot
ix Good long-distance performance
x Comparing human performance then and now
填空题 Paragraph B
填空题 Paragraph C
填空题 Paragraph D
填空题 Paragraph E
填空题 Paragraph F
填空题 Paragraph G