A recent paper in PLOS Genetics considers the origins of new “genes” in humans and chimps. By comparing RNA sequences, researchers identified over 600 transcriptionally active “genes” that appear to be present only in humans and not in chimps or the other mammal species tested. They claimed that these “genes” were the product of evolution from previously non-coding, untranscribed DNA. They argued that some of the “genes” are made into proteins and perhaps may be subject to selection, meaning that they are evolving.
I put genes in quote because this is not what the term gene typically means. It used to be that a gene was a stretch of DNA that coded for a protein, meaning it was a stretch of DNA that was copied into RNA (transcribed), and then translated into protein.
These researchers are using “gene” to signify any stretch of DNA that is copied (transcribed) into RNA and that meets certain criteria (size, the frequency with which they found it, etc.). They do not require that the RNA be turned into protein. In fact most of the time it probably isn’t. But still they call them genes. Only in some cases do they find evidence that these genes actually make protein, protein that may be evolving new functions, they say. More.
What new functions? How do we know if they are evolving new functions? How do we know if they are not?
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