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人类DNA竟然和黑猩猩99%都一样?

Are We Really 99% Chimp?

人们常说 人类和香蕉的DNA50%是相似的
It’s often said that we humans share 50 percent of our DNA with bananas, 80 percent
80%与狗的相似 99%和黑猩猩的相似
with dogs, and 99 percent with chimpanzees.
这听起来就好像 我们可以从猩猩和人类身上各取一个细胞
Taken literally, those numbers make it sound like we could pluck one cell from a chimp
提取染色体上缠在一起的DNA
and one from a human, pull out the tangled bundles of DNA known as chromosomes, unroll
像卷轴一样展开 提取出两列几乎相同的字序列
each one like a scroll, and read off two nearly identical strings of letters.
但事实上 人类和和黑猩猩的卷轴并不那么吻合
But in reality, the human and chimp scrolls don’t sync up so easily.
在我们从最后一位共同祖先分化之后的6-8百万年间
In the six to eight million years since we split from our last common ancestor, chance
突变和自然选择以独特和激进的方式改变了我们的基因组
mutations and natural selection have changed each of our genomes in radical – and unique – ways.
人类有两个基因合二为一 使我们比猩猩少了一对染色体 剩23对
Two human scrolls fused, leaving us with 23 pairs of chromosomes to chimps’ 24.
其他大量的突变则改变了大段的遗传信息 在这儿复制了一大段人类DNA
Other large mutations revised huge sections of text – duplicating a chunk of a human DNA here
然后在那删除一大段黑猩猩的DNA 而在整幅卷轴中
erasing a chunk of chimp DNA there – while, throughout the scrolls, tiny mutation
都是这种个别字母被替换的小差异
swapped one letter for another.
当研究人员开始比较黑猩猩和人类基因组时 这单字节差异
When researchers sat down to compare the chimp and human genomes, those single-letter differences
很容易被找到
were easy to tally.
但是大的片段差异……则并非如此
But the big mismatched sections…weren’t.
例如 一段含有几千个字母的基因片段 在人类卷轴里出现了两次
For example, if a genetic paragraph – thousands of letters long – appears twice in a human
而在黑猩猩的卷轴里只出现了一次 另一段基因中有几千种差异
scroll, but only once in its chimp counterpart, should the second copy count as thousands
还是只有一种?
of changes, or just one?
再者 相同的片段在两者基因组中都出现 但在不同的位置
And what about identical paragraphs that appear in both genomes, but in different places,
或顺序相反 或变成分散的片段
or in reverse order, or broken up into pieces?
与其对着这些难题瞎忙活 研究人员已经轻松排除了
Rather than monkey around with these difficult questions, the researchers simply excluded
13亿差异较大的DNA序列 然后
all the large mismatched sections – a whopping 1.3 billion letters of DNA – and performed
对剩下的24亿进行逐个比较 得出相似度是98.77%的结论
a letter-by-letter comparison on the remaining 2.4 billion, which turned out to be 98.77% identical.
没错 我们的DNA跟黑猩猩相似度高达99% 前提是忽略了18%的黑猩猩基因
So, yes, we share 99% of our DNA with chimps – if we ignore 18 percent of their genome
和25%的人类基因
and 25 percent of ours.
还有一个问题:句子中一个小小的停顿 就可能完全改变句子的意思
And there’s another problem: just as a small tweak to a sentence can alter its meaning
或者毫无影响 有时 DNA中的一点点变化 会令生物的
entirely or not at all, a few mutations in DNA sometimes produce big changes in a creature’s
外观或习性发生巨变 而有时大的变化只会造成细小的差异
looks or behavior, whereas other times lots of mutations make very little difference.
所以仅仅计算基因变化的数量 还无法说明
So just counting up the number of genetic changes doesn’t really tell us that much about
两个物种是否相似
how similar or different two creatures are.
这并不表示比较基因组的做法是徒劳的
But that doesn’t mean we can’t learn anything by comparing their genomes.
DNA中记录着所有物种的进化关系
DNA contains a record of the evolutionary relationships between all organisms.
这些记录杂乱无章 但通过细致的研究 我们就能够获得足够的信息
It’s a garbled record – but by reading closely, we’ve been able to glean enough
以对在基因测序出现前 就开始绘制的进化树进一步补充
information to refine the evolutionary trees we started drawing long before genome sequencing was around.
我们或许不是99%的黑猩猩
We may not actually be 99 percent chimp
但我们是100%的猿……或许还带点香蕉血统
but we are 100 percent great ape…and at least a little bananas.
嗨 我是艾米丽
Hi, this is Emily.
这集由Squarespace提供给您 该公司可以让你
This episode was brought to you in part by Squarespace, the company that will allow you,
就算没有编码或网页设计经验 也可以2015年做一个
even if you have no coding or web design experience whatsoever, to make a website in 2015 that
像一个2015年的网站 也就是说
looks and acts like a website from 2015 – which is to say
在你的智能手机浏览器上很漂亮的网页
beautiful and functional on your smartphone and in your browser.
登陆Squarespace.com/minuteearth 免费使用Squarespace 不需要信用卡
Go to Squarespace.com/minuteearth to try Squarespace out for free, with no credit card required,
首次购买返10%
and get 10% off your first purchase.

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视频概述

人类和黑猩猩的相似度研究

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收集自网络

翻译译者

SIDE B

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视频来源

https://www.youtube.com/watch?v=IbY122CSC5w

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