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科学家最想做的不道德试验之人猿杂交 [Copy link] 中文

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Post time 2012-10-19 16:51:28 |Display all floors

人猿杂交
试验:人和黑猩猩杂交繁育
The Experiment:Cross-breed a human with a chimpanzee.

试验背景:
The premise:

伟大的生物学家史蒂芬·杰伊·古尔德称这个试验是“我所能想到的最有趣的也是伦理上最不能接受的”。什么试验呢?人和黑猩猩交配。古尔德在研究蜗牛时发现:同属近亲的不同蜗牛外壳的构造却百样千种,他由此对人猿杂交的怪诞想法产生了兴趣。古尔德把蜗牛的多样性归因于几个主导基因,这些主导基因启动或关闭调控外壳构造基因中的部分片段。古尔德推测,人和类人猿之间的巨大差异显而易见,但这可能只是基因发育时间差异的结果。他指出,成年人类的某些身体特征,如头盖骨较大、眼间距较宽,和幼年黑猩猩类似,这种现象被称为幼态持续,也就是成年后仍然保留幼年的某些性状。古尔德提出了一个假说,进化过程中幼态持续的不断积累可能是猿最终进化成人的原因之一。如果能够直接观察半人半猿生物的发育过程,这个假说就能直接得到验证。
The great biologist Stephen Jay Gould called it “the most potentially interesting and ethically unacceptable experiment I can imagine.” The idea? Mating a human with a chimp. His interest in this monstrosity grew out of his work with snails, closely related species of which can display wide variation in shell architecture. Gould attributed this diversity to a few master genes, which turn on and off the shared genes responsible for constructing the shells. Perhaps, he speculated, the large visible differences between humans and apes were also a factor of developmental timing. He pointed out that adult humans have physical traits, such as larger craniums and wide-set eyes, that resemble infant chimpanzees, a phenomenon known as neoteny—the retention of juvenile traits in adults. Gould theorized that over the course of evolution, a tendency toward neoteny might have helped give rise to human beings. By watching the development of a half-human, half-chimp, researchers could explore this theory in a firsthand (and truly creepy) way.

试验过程:
How it works:

出奇的简单:用体外受精技术就能制造出可以正常发育的人猿杂交胚胎。研究人员已经培育出了恒河猴和狒狒的杂交后代,人与猿之间的基因差距和这两者之间的基因差异相当。黑猩猩有24对染色体,人类有23对,不过这并不能完全阻止两个物种间的杂交。不过他们后代的染色体可能不成对,因而不能继续繁育。至于妊娠和生产,都可以采用自然的方式,黑猩猩新生儿比人类新生儿稍小,重4磅(约1.8千克)左右。所以从解剖学的角度考虑,人和猿的杂交后代应该在人类子宫内孕育。
It would probably be frighteningly easy: The same techniques used for in vitro fertilization would likely yield a viable hybrid human-chimp embryo. (Researchers have already spanned a comparable genetic gap in breeding a rhesus monkey with a baboon.) Chimps have 24 pairs of chromosomes, and humans 23, but this is not an absolute barrier to breeding. The offspring would likely have an odd number of chromosomes, though, which might make them unable to reproduce themselves. As for the gestation and birth, it could be done the natural way. Chimpanzees are born slightly smaller than humans, on average—around 4 pounds—and so comparative anatomy would argue for growing the embryo in a human uterus.

研究意义:
The payoff:

至少可以说,古尔德的幼态持续理论仍存在争议。哈佛大学人类进化生物学教授丹尼尔·利伯曼说:“这种理论受到多次审查,已经被多种方法证明是错误的。”但是加州大学戴维斯分校人类学名誉教授亚历山大·哈克特认为幼态持续的解释依然是可行的。如果人猿杂交的试验付诸实施,关于古尔德幼态持续理论的争论就可以水落石出了,而且,在更广泛的意义上,这项不道德的试验有助于阐释两个基因及其相似的物种为什么会有这么大的差异。试验结果将引领生物学家深入探讨我们最关心的物种——人的起源。我们只希望找到这个答案的道路不会那么崎岖。
Gould’s idea about neoteny remains controversial, to say the least. “It got a lot of scrutiny and has been disproved in many ways,” says Daniel Lieberman, a Harvard professor of human evolutionary biology. But Alexander Harcourt, professor emeritus of anthropology at UC Davis, regards neoteny as “still a viable concept.” This forbidden experiment would help to resolve that debate and, in a broader sense, illuminate how two species with such similar genomes could be so different. Its outcome would take biologists deep into the origin of the species we care about most: ourselves. Let’s just hope we can find a less disturbing route to get there.


来源:译言网

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