Word: dna
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When an inversion, deletion or duplication occurs in an unused portion of the genome, nothing much changes--and indeed, the human, chimp and other genomes are full of such inert stretches of DNA. When it happens in a gene or in a functional noncoding stretch, by contrast, an inversion or a duplication is often harmful. But sometimes, purely by chance, the change gives the new organism some sort of advantage that enables it to produce more offspring, thus perpetuating the change in another generation...
Comparisons of primitive genomes have also led to an astonishing, controversial and somewhat disquieting assertion about the origin of humanity. Along with several colleagues, David Reich of the Broad Institute in Cambridge, Mass., compared DNA from chimpanzees and humans with genetic material from gorillas, orangutans and macaques. Scientists have long used the average difference between genomes as a sort of evolutionary clock because more closely related species have had less time to evolve in different directions. Reich's team measured how the evolutionary clock varied across chromosomes in the different species. To their surprise, they deduced that chimps and humans...
...last 10,000 to 15,000 years." We eventually outcompeted them, and the key to how we did so may well lie in our genes. So two years ago, Svante Pääbo, the man who deconstructed the FOXP2 language gene and has done considerable research on ancient DNA, launched an effort to re-create the Neanderthal genome. Rubin, meanwhile, is tackling the same task using a different technique...
...easy one. Like any complex organic molecule, DNA degrades over time, and bones that lie in the ground for thousands of years become badly contaminated with the DNA of bacteria and fungi. Anyone who handles the fossils can also leave human DNA behind. After probing the remains of about 60 different Neanderthals out of the 400 or so known, Pääbo and his team found only two with viable material. Moreover, he estimates, only about 6% of the genetic material his team extracts from the bones turns out to be Neanderthal DNA...
Although Pääbo admits that he still hasn't learned much about what distinguishes us from our closest cousins, simply showing he can reconstruct significant DNA sequences from such long-dead creatures is an important proof of concept. Both he and Rubin agree that within a couple of years a reasonably complete Neanderthal genome should be available. "It will tell us about aspects of biology, like soft tissue, that we can't say anything about right now," Rubin notes. "It could tell us about disease susceptibility and immunity. And in places where the sequence overlaps that of humans...