Wednesday, November 30, 2011
60 "de novo" genes found in humans
An international team of researchers from Canada and China have recently discovered 60 genes in humans that were produced spontaneously from non-coding DNA (also known as "junk" DNA) since our lineage spit from that of chimpanzees several million years ago. It was only two years ago that scientists first discovered that not all "new" human genes were the product of mutation of previously existing genes. Rather, some of our genes were spontaneously created from genetic material that previously did not code for proteins, and thus were not technically genes. These genes which seem to, in a sense, appear out of nowhere, are called "de novo" genes.
Until this most recent study, it was thought that humans had only a very few de novo genes, with 3 or 4 being created every million years. But this study shows that the rate is in fact between 10 and 12 for each million years, three times higher than previously estimated. The scientists made this discovery by combing through the human genome and comparing it to the genomes of the apes most closely related to us and then ruling out all genes that resembled those (either activated or deactivated) in the apes. The 60 out of around 25,000 genes that were left over after this process was completed were considered "de novo."
This discovery is particularly interesting because the majority of the de novo genes discovered seemed to be involved in the functioning of the cerebral cortex, the part of the brain responsible for dealing with memory, emotions, language, and various other functions that most of us deem as critical to making us human. There is, however, some doubt about the specific role these genes play in the cerebral cortex, and whether they have really contributed significantly to the most obvious differences between ourselves and apes. Further research will be difficult since the necessary experimentation is obviously not possible to perform on living humans, but there are hopes that by continuing research on apes or other lab animals further results can be produced.
The original article from Scientific American describing the results of the study can be found here.