马牙齿化石印证“人如其食”的道理-凯发k8官网

马牙齿化石印证“人如其食”的道理
文章来源:未知 文章作者:enread 发布时间:2011-03-04 01:54 字体: [ ] 
(单词翻译:双击或拖选)

fossil records verify a long-standing theory that horses evolved through natural selection, according to groundbreaking research by two 1(解剖学) professors at new york college of osteopathic medicine (nycom) of new york institute of technology. working with colleagues from massachusetts and spain, matthew mihlbachler, ph.d., and nikos solounias, ph.d. arrived at the conclusion after examining the teeth of 6,500 fossil horses representing 222 different populations of more than 70 extinct horse species. the records, spanning the past 55 million years, indicate a "critical" lag time between the evolution of horse teeth and dietary changes resulting from climate change. the breakthrough findings were chosen for publication in the march 4 issue of the 2 bi-weekly international journal science.

"one of the advantages of studying extinct creatures like 3 horses is we can look at how animals responded to their environments over millions of years—something that biologists who study living species cannot do," mihlbachler said, adding that the biggest surprise of the study was that while some of the extinct populations they examined had extremely 4(粗糙的) diets, much of the time, it seemed horses had it surprisingly easy. this suggests that "strong natural selection" for different types of teeth only happened occasionally during brief 5 in horse history.

solounias helped develop a methodology(方法学) known as dental mesowear analysis to reconstruct the diets of extinct species by measuring food-related wear and tear on fossil teeth. he and mihlbachler used the process to investigate wear patterns on the molars of thousands of fossil horses. they later 6 their data alongside records of north american climate changes that would have shifted the animals' diets from rainforest fruits and woody, leafy vegetation to the more abrasive(粗糙的) diets found in 7.

"lag time in the evolution of horse teeth in comparison to dietary changes is critical," mihlbachler explained. "we found that 8 changes in tooth anatomy(解剖学) lag behind the dietary changes by a million years or more."

while paleontologists(古生物学者) have long held horses as classic examples of evolution through natural selection, the theory has been difficult to test because the majority of horse species are extinct. however, mihlbachler and solounias' observation that dental changes in horses follow their dietary changes is consistent with evolution due to adaptation.

"'you are what you eat': we hear this all the time, but now we know it is true," explained thomas scandalis, dean of nycom. "this study shows that the evolutionary path of horses as we know them today was 9 by the food available to their prehistoric ancestors."

the duo's research shows that not only has the number of horse species been greatly reduced in the past few million years, but also that the diets of horses have been narrowly restricted. "living horses are anything but typical examples of the dietary ecology of this once great group of mammals," solounias said.



点击收听单词发音收听单词发音  

1 cwgzh     
n.解剖学,解剖;功能,结构,组织
参考例句:
  • he found out a great deal about the anatomy of animals.在动物解剖学方面,他有过许多发现。
  • the hurricane's anatomy was powerful and complex.对飓风的剖析是一项庞大而复杂的工作。
2 nq2xn     
adj.有威望的,有声望的,受尊敬的
参考例句:
  • the young man graduated from a prestigious university.这个年轻人毕业于一所名牌大学。
  • you may even join a prestigious magazine as a contributing editor.甚至可能会加入一个知名杂志做编辑。
3 spvxq     
adj.(有记载的)历史以前的,史前的,古老的
参考例句:
  • they have found prehistoric remains.他们发现了史前遗迹。
  • it was rather like an exhibition of prehistoric electronic equipment.这儿倒像是在展览古老的电子设备。
4 3ydz3     
adj.使表面磨损的;粗糙的;恼人的
参考例句:
  • his abrasive manner has won him an unenviable notoriety.他生硬粗暴的态度让他声名狼藉。
  • she had abrasions to her wrists where the abrasive rope had scraped her.她的手腕有多出磨伤,那是被粗糙的绳子擦伤的。
5 f46c9d8b430e8c86dea610ec56b7cbef     
n.[军事]间隔( interval的名词复数 );间隔时间;[数学]区间;(戏剧、电影或音乐会的)幕间休息
参考例句:
  • the forecast said there would be sunny intervals and showers. 预报间晴,有阵雨。
  • meetings take place at fortnightly intervals. 每两周开一次会。
6 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
参考例句:
  • the doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • the young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
7 72179cad53224d2f605476ff67a1d94c     
n.草原,牧场( grassland的名词复数 )
参考例句:
  • songs were heard ringing loud and clear over the grasslands. 草原上扬起清亮激越的歌声。 来自《现代汉英综合大词典》
  • grasslands have been broken and planted to wheat. 草原已经开垦出来,种上了小麦。 来自《简明英汉词典》
8 ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • life has its own evolutionary process.生命有其自身的进化过程。
  • these are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
9 tzuzg0     
adj.不自然的,假装的
参考例句:
  • she showed an affected interest in our subject.她假装对我们的课题感到兴趣。
  • his manners are affected.他的态度不自然。
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