Billions of years ago, organic chemicals in the primordial soup somehow organized themselves into the first organisms. A few years ago scientists found that something similar happens every once in awhile in the cells of all living things: bits of once-quiet stretches of DNA sometimes spontaneously assemble themselves into genes. Such "de novo" genes may go on to play significant roles in the evolution of individual organisms—even humans. But how many are there?
More than anyone thought, it turns out.
The most prolific source of new genes in animals, plants, fungi and other life whose cells have nuclei involves the shuffling or duplication of bits of DNA from existing genes. It was widely thought that de novo evolution of genes was quite rare, because the proteins they code for are often large and complex—most fail to function properly if a single key component is out of place, so randomly evolving a working gene seemed implausible.
When an international team of researchers scanned the human genome for de novo genes, however, they putatively uncovered 60, three times more than once estimated. More surprising, many of these genes are active in the cerebral cortex, suggesting that de novo genes might have played a key role in the evolution of the human mind
No comments:
Post a Comment