(TIME杂志文章节选)What Makes us Different?
Posted: 2006-10-06 13:36
What Makes us Different?
Not very much, when you look at our DNA. But those few tiny changes made all the difference in the world
全文在以下链接,估计下周就没了。
http://www.time.com/time/magazine/artic ... 83,00.html
还有几处细节,挺好玩的。
人为什么会得一些猿猴不易得的病:
Allan Wilson要是还活着,恐怕能得炸弹奖,可惜他90年代初才50多就白血病过世了。
Not very much, when you look at our DNA. But those few tiny changes made all the difference in the world
全文在以下链接,估计下周就没了。
http://www.time.com/time/magazine/artic ... 83,00.html
哈哈,从雄猩猩到男人,进化的需要更大!……overall, the sequences of base pairs that make up both species' genomes (human and chimp)differ by 1.23%--a ringing confirmation of the 1970s estimates--and that the most striking divergence between them occurs, intriguingly, in the Y chromosome, present only in males. And when they compared the two species' proteins--the large molecules that cells construct according to blueprints embedded in the genes--they found that 29% of the proteins were identical (most of the proteins that aren't the same differ, on average, by only two amino-acid substitutions).
还有几处细节,挺好玩的。
人为什么会得一些猿猴不易得的病:
基因和语言的联系?As long ago as 1998, for example, glycobiologist Ajit Varki and colleagues at the University of California, San Diego, reported that humans have an altered form of a molecule called sialic acid on the surface of their cells. This variant is coded for by a single gene, which is damaged in humans. Since sialic acids act in part as a docking site for many pathogens, like malaria and influenza, this may explain why people are more susceptible to these diseases than, say, chimpanzees are.
下巴肌肉的重要性?A few years later, a team led by Pääbo announced that the human version of a gene called FOXP2, which plays a role in our ability to develop speech and language, evolved within the past 200,000 years--after anatomically modern humans first appeared. By comparing the protein coded by the human FOXP2 gene with the same protein in various great apes and in mice, they discovered that the amino-acid sequence that makes up the human variant differs from that of the chimp in just two locations out of a total of 715--an extraordinarily small change that may nevertheless explain the emergence of all aspects of human speech, from a baby's first words to a Robin Williams monologue. And indeed, humans with a defective FOXP2 gene have trouble articulating words and understanding grammar.
最后8卦两下:Then, in 2004, a team led by Hansell Stedman of the University of Pennsylvania identified a tiny mutation in a gene on chromosome 7 that affects the production of myosin, the protein that enables muscle tissue to contract. The mutant gene prevents the expression of a myosin variant, known as MYH16, in the jaw muscles used in biting and chewing. Since the same mutation occurs in all of the modern human populations the researchers tested--but not in seven species of nonhuman primates, including chimps--the researchers suggest that lack of MYH16 made it possible for our ancestors to evolve smaller jaw muscles some 2 million years ago. That loss in muscle strength, they say, allowed the braincase and brain to grow larger. It's a controversial claim, one disputed by anthropologist C. Owen Lovejoy of Kent State University. "Brains don't expand because they were permitted to do so," he says. "They expand because they were selected"--because they conferred extra reproductive success on their owners, perhaps by allowing them to hunt more effectively than the competition.
现在把人和黑猩猩的基因组实实在在对比,这个百分比还是对头的。所以虽然“分子钟”(molecular clock)受到一些质疑,我觉得大体上还是很有意义的。And by 1975, the then new science of molecular genetics had led to a landmark paper by two University of California, Berkeley, scientists, Mary-Claire King and Allan Wilson, estimating that chimps and humans share between 98% and 99% of their genetic material.
Allan Wilson要是还活着,恐怕能得炸弹奖,可惜他90年代初才50多就白血病过世了。
小火焰,认识这人么?A group led by geneticist Stephen Scherer of the Hospital for Sick Children in Toronto has identified 1,576 apparent inversions between the chimp and human genomes; more than half occurred sometime during human evolution.