下面是出國(guó)留學(xué)網(wǎng)小編為大家?guī)?lái)的英語(yǔ)聽力音頻：人類跟黑猩猩DNA相似度真的有99%。希望能對(duì)大家的英語(yǔ)口語(yǔ)和聽力練習(xí)有所幫助!
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It's often said that we humans share 50 percent of our DNA with bananas,80 percent with dogs,and 99 percent with chimpanzees.Taken literally,those numbers make it sound like we could pluck one cell from a chimp and one from a human,pull out the tangle bundles of DNA known as chromosomes,unroll each on elike a scroll,and read off two nearly identical strings of letters.
人們常說(shuō) 人類DNA與香蕉DNA的相識(shí)度50%，與狗的相似度80% 與黑猩猩相似度99%。這聽起來(lái)就好像 我們可以從猩猩和人類身上各取一個(gè)細(xì)胞，拖出染色體上纏成一團(tuán)的DNA，展成卷軸狀，然后讀取出兩列幾乎一樣的字母排序。
But in reality,the human and chimp scrolls don't sync up so easily.In the six to eight million years since we split from our last common ancestor,chance mutations and natural selection have changed each of our genomes in radical-and unique-ways.
但事實(shí)上，人類和黑猩猩的卷軸并沒那么同步。在我們從最后一位共同祖先分化之后的6-8百萬(wàn)年間，突變和自然選擇以獨(dú)特的方式徹底地改變了我們的基因組。
Two human scrolls fused,leaving us with 23 pairs of chromosomes to chimps' 24.Other large mutations revised huge sections of text-duplicating a chunk of a human DNA here.erasing a chunk of chimp DNA there-while throughout the scrolls,tiny mutations swapped one letter for another.When researchers sat down to compare the chimp and human genomes,those single letter differences were easy to tally.
人類卷軸的兩段融合，使我們只剩23對(duì)染色體而黑猩猩有24對(duì)。其他大量的突變則改變了大段的遺傳信息在這兒復(fù)制一大段人類DNA。在那兒刪除一大段黑猩猩DNA 個(gè)別字母替換這種小差異則遍布整幅卷軸研究員著手比較黑猩猩和人類基因時(shí)，可以輕松找出這些小差異。
But the big mismatched sections weren't.For example,if a genetic paragraph-thousands of letters long-appears twice in a human scroll,but only once in its chimp counterpart,should the second copy as thousands of changes,or just one?And what about identical paragraphs that appear in both genomes,but in different places,or in reverse order,or broken up into pieces?
但是大的片段差異...則不然例如，一段含有幾千個(gè)字母的基因片段 在人類卷軸里出現(xiàn)了兩次。而在黑猩猩卷軸里只出現(xiàn)了一次。那么多出來(lái)的這段基因應(yīng)該視為幾千個(gè)差異還有一個(gè)?再例如 相同的片段在兩者基因組中都出現(xiàn)，但是位置不同。或順序變化，或變成分散的片段又該怎么算呢?
Rather than monkey around with these difficult questions,the researchers simply excluded all the large mismatched sections- a whopping 1.3 billiion letters of DNA-and performed a letter by letter comparison on the remaining 2.4 billion,which turned out to be 98.77% identical.So,yes,we share 99% of our DNA with chimps-if we ignore 18 percent of their genome and 25 percent of ours.
與其對(duì)著這些難題瞎忙活，研究人員干脆刪除了13億 差異較大的DNA序列 然后對(duì)剩余的24億進(jìn)行逐字比較，得出了相似度98.77%的結(jié)論。是的，我們的DNA跟黑猩猩相似度高達(dá)99%前提是忽略18%的黑猩猩基因和25%的人類基因。
And there's another problem:just as a small tweak to a sentence can alter its meaning entirely or not at all,a few mutations in DNA sometimes produce big changes in a creature's looks or behavior,whereas other times lots of mutations make very little difference.So just counting up the number of genetic changes doesn't really tell us that much about how similar or different two creatures are.
還有一個(gè)問題:句子中一個(gè)小小的停頓就可能完全改變句子的意思也可能毫無(wú)影響，有時(shí)一點(diǎn)點(diǎn)的DNA變化會(huì)令生物的外觀或行為發(fā)生巨變，而有時(shí)大段的變化只會(huì)造成些微差異。因此只是數(shù)數(shù)基因變化的數(shù)量 并沒辦法說(shuō)明兩個(gè)物種是否相似。
But that doesn't mean we can't learn anything by comparing their genomes.DNA contains a record of the evolutionary relationships between all organisms.It's a garbled record-but by reading closely,we've been able to glean enough information to refine the evolutionary trees we started drawing long before genome sequencing was around.
當(dāng)然這并不表示比較基因組的做法一無(wú)是處。DNA中記錄著所有物種的進(jìn)化關(guān)系。這些記錄雜亂無(wú)章但通過(guò)細(xì)致的研究。我們就能夠收集到足夠的信息，完善早在基因組測(cè)序出現(xiàn)前就開始繪制的基因樹。
We may not actually be 99 percent chimp,but we are 100 percent great ape...and at least a little bananas.
我們或許當(dāng)成不了99%的黑猩猩。但我們是100%的人類猿。。?；蛟S還捎帶點(diǎn)香蕉血統(tǒng)。