Cracking the Neanderthal code_英文原版

two new studies show how to sequence the genome of an extinct species

recreating dinosaurs may be the stuff of science fiction—but scientists have for some years been able to extract information from the remains of species that no longer walk the earth. unfortunately this evidence is often in the form of tiny, jumbled snippets and it is frequently contaminated. two new ways to patch the oddments together and distinguish genuine from false information are reported this week. scientists intend to use the techniques to produce the complete genome of a creature that is not only extinct but also happens to be their closest relative.

when humans first emerged as a species they shared the planet with many types of ape. the fossilised remains of one such species were discovered in the neander valley in germany some 150 years ago. neanderthal man, as the species has come to be called, was shorter and stockier than humans. the evidence suggests that he was a cousin rather than an ancestor of humanity. mitochondrial extracted from the bones of neanderthals does not resemble from any known modern humans, so scientists have concluded that there was no interbreeding between the two, which is what distinguishes one species from another.

nevertheless neanderthal man is thought to be man's closest relative. if scientists could recreate his genome, the strings of billions of letters that spell out how to build and run a neanderthal, they would be able to pinpoint the precise difference between the two species. moreover, by comparing the two genomes, they could see what makes people human. until now many researchers have argued that it would be impossible to sequence the entire genome of an extinct creature because the samples are so degraded. how could so many tiny fragments of be pieced together? and how would it be possible to check whether the jigsaw pieces had been assembled correctly?