時差N小時:遺傳錯誤和大腦理論 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.

當細胞分裂自我復制或者生成精子和卵子時，總有機會發(fā)生遺傳錯誤。

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

當一個常規(guī)基因被復制兩次，基因復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.

基因復制通常是有害的，如果沒有得到細胞修復機制修復的話，會導致變形和死亡。

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

但在極少數(shù)情況下，它也許對進化很重要。

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進化重要性的科學家們認為他們已經(jīng)發(fā)現(xiàn)了復制錯誤，該錯誤揭示了在進化過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.

當研究SRGAP2這個同癲癇發(fā)作相關(guān)的基因時，科學家們發(fā)現(xiàn)基因不只復制一次，而是在人類的血統(tǒng)中多次復制。

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SRGAP2基因的分析確定了復制發(fā)生在340萬年至240萬年前，那時，同黑猩猩相似的人類祖先正進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.

為了測試復制了的基因它的功能，科學家們將人類基因的復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.

小鼠并未長出更大的大腦，但是他們的腦細胞看起來象人類的細胞，有著更厚，更長，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)元也生長得非?？欤@表明它們在生長過程中能移動的更遠，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.

自六百萬年前，人類和黑猩猩從同一個祖先分離開來，大約有30個基因已經(jīng)發(fā)生基因復制。

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化，研究人員猜測基因復制是揭開圍繞在人類大腦進化周圍謎題的關(guān)鍵。