腦公 我的眼睛好像被什麼遮住了
貧窮遮住了我的雙眼
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腦公 我的眼睛好像被什麼遮住了
貧窮遮住了我的雙眼
表情包
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Line up the genomes of humans and chimps side by side and they differ by little more than 1 per cent. That may not seem like much, but it equates to more than 30 million point mutations. Around 80 per cent of our 30, 000 genes are affected, and although most have just one or two changes (Gene, vol 346, p 215), these can have dramatic effects. The protein made by the human geneFOXP2, which helps us to speak, differs from its chimp counterpart by just two amino acids, for example. And small changes in the microcephalin andASPM genes may underlie big differences in brain size between humans and chimps.
But protein evolution is only part of what makes us human. Also critical are changes in gene regulation - when and where genes are expressed during development - says James Noonan of Yale University. Mutations in key developmental genes are likely to be fatal. But, he says: "Altering the expression of a gene in a single tissue or at a single time can more easily lead to an innovation that is not lethal." Noonan's lab is one of many that are busy comparing gene expression in tissues such as the brain to home in on the key regulatory difference between chimps and humans, most of which have still to be uncovered.