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Development of a widely accepted chronology for the arrival of humans has been equally difficult, and it was only with the development of optically stimulated luminescence dating that a human presence in Australia was confirmed at 53,000 to 60,000 years ago. Older dates for a human presence in Australia have now been shown to be erroneous .
The importance of Australia as a separate natural laboratory in which to test extinction theories lies in the fact that humans arrived there much earlier than they arrived in the other continental areas (the Americas and northern Eurasia) that experienced substantial
megafaunal extinction. What Miller et al. have shown is that the extinction of Genyornis occurred simultaneously across southeastern Australia (indeed probably right across the continent) about 50,000 years ago. This is very close to the presently accepted time of
arrival of humans in Australia. It was also a period of modest climate change, well before the dramatic climatic fluctuations of the terminal Pleistocene. The data of Miller et al., therefore, support those who see human hunting rather than climate as causing the extinction of the megafauna.
Genyornis was a ponderous bird, around 80 to 100 kg in weight, about twice as heavy as the living emu and cassowary. It was an inhabitant of Australias inland plains and some coastal regions, but its legs were relatively short and thick, suggestion that it was a slower runner than the emu. Proponents of humancaused extinction suggest that it is just such characteristics that made the megafauna vulnerable to human hunting.
A new school of thought has recently established itself in the extinction debate. It advocates the idea that a combination of human impact and climate change was responsible for the extinction of the worlds megafauna. The new Genyornis data also weaken that argument, for the following reason. Fifty thousand years ago, Australia was experiencing mild cooling; 11,000 to 12,000 years ago, the Americas were experiencing rapid warming. These disparate climatic conditions, all coincident with megafaunal extinction, suggest that whatever was happening with climate, it was bad for the big animals. Under these
conditions, the hybrid model becomes indistinguishable from the humancaused extinction model for the influence of climate becomes extremely weak, and only the arrival of humans is important in predicting extinction.［382 words］
1. The last word “megafauna” in Paragraph 2 most probably means
［A］ birds. ［B］ plants.
［C］ big animals. ［D］ small animals.
2. Genyornis was vulnerable to human hunting because it was
［A］ a delicacy. ［B］ very weak.
［C］ very small in size. ［D］ clumsy.
3. How many models have been put forward for the extinction of Genyoris?
［A］ One. ［B］ Two.
［C］ Three. ［D］ Four.
4. That Australia experienced mild cooling and the Americas rapid warming suggests that
［A］ the climatic conditions were unfit for Genyornis to live.
［B］ Genyornis were highly adaptable to different climatic conditions.
［C］ The two climatic conditions were both bad for Genyornis.
［D］ The climatic conditions had nothing to do with the extinction of Genyoris.
5. The selection is mainly about(此题与2004年第55题相仿)
［A］ the debate over the time of the human presence in Australia.
［B］ the relationship between the human presence and magafaunal extinction.
［C］ the relationship between human activities and climatic changes.
［D］ the debate over factors causing megafaunal extinction.
-核心及超纲词汇
1.chronologyn.年代学
2.luminescencen.发光
3.erroneousa.错误的 ［同义］ false, incorrect, inexact
4.megafaunan.巨型动物
5.fluctuationn.变化 ［同义］ oscillation, rolling
6.ponderousa.笨重的 ［同义］ heavy, weighty, massive, bulky
7.cassowaryn.食火鸡
-全文精译
澳洲古代巨鸟灭绝探因
要创建人类是何时到来的、且为人们所广为接受的年代表同样也是困难的。并且只有在光学模拟发光测定年代的方法发展起来后，人们才确定53，000年到60，000年前澳洲有了人类，现在已证明更久远的年代是错误的。
之所以把澳洲称为试验种族灭绝理论的天然实验室，其重要性在于(lie in)：人类到达这儿的年代要远远先于到达经历过巨型动物灭亡的其他大陆(如欧洲和欧亚大陆北部)的年代。Miller等人向我们说明，“巨鸟”于50，000年前在澳洲南部同时灭绝，这和人们普遍接受的人类到达澳洲大陆的时间相当接近。这也是气候温和的时期，随后很久才发生了更新世晚期灭绝性的气候剧变。Miller的资料支撑了认为人类捕猎而非气候变化是巨兽灭绝的原因的观点。
“巨鸟”是远古时期一种巨型鸟类，重约80到100公斤，是鸸鹋和食火鸡的两倍重。它是澳洲内陆和沿海地区的动物，但它的腿相对短而粗，证明它不如鸸鹋跑得快。坚持人类导致这种鸟灭绝的人说，它们的这种特性使它们很容易受到(be vulnerable to ...)捕杀。
在这一“灭绝争论”中，新的学派又建立了。他们赞成人类及气候因素结合导致(be responsible for ...)了世界范围巨型动物的灭绝的观点。新的巨鸟资料也削弱了这种争论，原因如下：50，000年前，澳洲气候逐渐变冷；11，000到12，000年前，美洲气温迅速上升。这些完全相异的气候条件正好与巨鸟灭绝时期相吻合(be coincident with)。这说明，无论气候怎样变化，巨型动物还是难逃厄运。在这种情况下(under these conditions)，这种结合两种说法的观点就变得与人类导致其灭绝的观点难以区别了。因为在他们看来，气候影响是那么微弱，只有人类的到来才预示了巨型动物的灭绝。
-答案详解
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