時(shí)差N小時(shí):遺傳錯(cuò)誤和大腦理論 Genetic Error and the Big Brain Theory

When cells divide to create copies of themselves or tomakesperm and eggs, there is always a chance ofgenetic error.

當(dāng)細(xì)胞分裂自我復(fù)制或者生成精子和卵子時(shí)，總有機(jī)會(huì)發(fā)生遺傳錯(cuò)誤。

Gene duplication, when a regular geneis copiedtwice, is one of those mishaps.

當(dāng)一個(gè)常規(guī)基因被復(fù)制兩次，基因復(fù)制就是這些失誤中的一種。

Gene duplication is usually detrimental and canlead to deformation and death if not caught bythecell’s repair machinery.

基因復(fù)制通常是有害的，如果沒(méi)有得到細(xì)胞修復(fù)機(jī)制修復(fù)的話，會(huì)導(dǎo)致變形和死亡。

But in rare instances, it may also be evolutionarily important.

但在極少數(shù)情況下，它也許對(duì)進(jìn)化很重要。

Scientists researching genes important in brain development believe they have foundduplicationerrors that reveal how the human brain increased in size during evolutionaryhistory.

研究基因?qū)Υ竽X進(jìn)化重要性的科學(xué)家們認(rèn)為他們已經(jīng)發(fā)現(xiàn)了復(fù)制錯(cuò)誤，該錯(cuò)誤揭示了在進(jìn)化過(guò)程中人類大腦的體積是如何增加的。Whilestudying SRGAP2, a gene linkedto epileptic seizures, scientists found that the gene had not onlyduplicated once, but a numberof times throughout human lineage.

當(dāng)研究SRGAP2這個(gè)同癲癇發(fā)作相關(guān)的基因時(shí)，科學(xué)家們發(fā)現(xiàn)基因不只復(fù)制一次，而是在人類的血統(tǒng)中多次復(fù)制。

Analysis of the SRGAP2 genes determined that duplications occurred 3.4 and 2.4 million yearsago,during which time chimp like ancestors were evolving into the first pre humans and humanlikeancestors.

對(duì)SRGAP2基因的分析確定了復(fù)制發(fā)生在340萬(wàn)年至240萬(wàn)年前，那時(shí)，同黑猩猩相似的人類祖先正進(jìn)化成為史前人類和類人祖先。

To test the function of the duplicated genes, scientists inserted human copies into mice.

為了測(cè)試復(fù)制了的基因它的功能，科學(xué)家們將人類基因的復(fù)制品注入到小鼠體內(nèi)。

The micedidn’t grow larger brains, but their brain cells looked more like human cells withthicker, longer andmore numerous spines to connect with other neurons.

小鼠并未長(zhǎng)出更大的大腦，但是他們的腦細(xì)胞看起來(lái)象人類的細(xì)胞，有著更厚，更長(zhǎng)，更多的棘狀突起同其他神經(jīng)元相連，

The neurons also grew more quickly,suggesting they could migrate farther during developmentand enable the brain to become larger.

神經(jīng)元也生長(zhǎng)得非常快，這表明它們?cè)谏L(zhǎng)過(guò)程中能移動(dòng)的更遠(yuǎn)，大腦也能變得更大。

About 30 genes have undergone gene duplication since humans and chimps diverged fromacommon ancestor about six million years ago.

自六百萬(wàn)年前，人類和黑猩猩從同一個(gè)祖先分離開(kāi)來(lái)，大約有30個(gè)基因已經(jīng)發(fā)生基因復(fù)制。

Many of these genes control brain development.Researchers suspect that gene duplicationis the key to unlocking the mysteries surroundinghuman brain evolution.

這其中的許多基因控制著大腦進(jìn)化，研究人員猜測(cè)基因復(fù)制是揭開(kāi)圍繞在人類大腦進(jìn)化周?chē)i題的關(guān)鍵。