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You are what you eat. This saying has provided1 scientists with clues2(线索)about the diet of hominids- our early relatives of 3 million years ago.
Studying carbon3 atoms(碳原子)locked up in tooth enamel4(珐琅质),two researchers argue against the widely held belief that hominids ate little more than fruits and leaves. Sponheimer and Julia Lee-Thorp of the University of Cape5 Town, South Africa, report their findings6 in Friday’s Science.
There aren’t many clues for us to know the life of early hominids. The shape of hominids’ teeth offered the first clues. Large and flat-edged with thick enamel, they looked perfect for eating nuts and fruits, different from the sharp teeth one would want to tear into meat with. The first stone tools, which would help in eating meat, didn’t appear until about half a million years later.
Scientists have also found marks on hominids’ teeth with patterns very similar to those on the teeth of modern-day fruit eaters. Sponheimer and Lee-Thorp tried a new method , looking at the chemical composition of the tooth enamel. They studied the enamel for the carbon-13. Animals that eat grasses have higher carbon-13 levels than those eating fruits and other plants.
What they found was that the teeth to the hominids had an in-between amount of carbon-13, which meant not only they were eating fruits, they were eating a lot of grasses, or animals eating grasses. The lower7 carbon-13 levels could also come from eating certain types of insects (昆虫).
But there are people who understand differently. Prof. Ungar of the University of Arkansas agrees the study offers new suggestions of hominids diet, but disagrees about the suggestion that meat could explain the lower carbon-13 levels .
One suggestion might be true though-take good care of your teeth .In 3 million years, a scientist might be using them to figure out what you ate for dinner.
64. Which of the following can be the best title for the text?
A. Protect Your Teeth B. What the Hominid Ate C. Where the Hominid lived D. The Formation8 of Teeth Enamel
65. Before the two scientists' findings, most people thought that hominids______.
A. lived half a million years ago B. ate mainly fruits and leaves
C. used tools to dig9 grass D. had sharp teeth.
66. The two scientists' findings were mainly based on the study about _____.
A. the shape of hominids' teeth B. the teeth marks of early fruit eaters
C. the grasses of 3 million years ago D. the make-up of the tooth enamel
67. What is it that Prof. Ungar finds doubtful10?
A. Hominids possibly ate grass-eating animals. B. Hominids probably had different diets.
C. Hominids were basically11 fruit- and grass-eaters. D. Hominids had lower level of carbon-13 in the teeth.
1 provided | |
conj.假如,若是;adj.预备好的,由...供给的 | |
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2 clues | |
n.线索( clue的名词复数 );提示;(帮助警方破案的)线索;(纵横填字谜、游戏或问题的)提示词语 | |
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3 carbon | |
n.碳元素 | |
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4 enamel | |
n.珐琅,搪瓷,瓷釉;(牙齿的)珐琅质 | |
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5 cape | |
n.海角,岬;披肩,短披风 | |
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6 findings | |
n.发现物( finding的名词复数 );调查(或研究)的结果;(陪审团的)裁决 | |
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7 lower | |
adj.较低的;地位较低的,低等的;低年级的;下游的;vt.放下,降下,放低;减低 | |
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8 formation | |
n.形成,组成;形成物,结构;队形,排列 | |
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9 dig | |
v.挖(洞,沟等);掘 | |
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10 doubtful | |
adj.难以预测的,未定的;怀疑的,可疑的 | |
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11 basically | |
adv.基本上,从根本上说 | |
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