#PLOSGenetics: The Case for Junk DNA

This is the paper to read: Palazzo & Gregory’s The Case for Junk DNA. It clearly and logically lays out the complete argument from evidence and theory for the thesis that most of the genome is junk. It’s not revolutionary or radical, though: the whole story is based on very fundamental population genetics and molecular biology, and many decades of accumulated observations. And once you know a little bit of those disciplines — you don’t need to be a genius with a great depth of understanding — the conclusion is both obvious and in some ways, rather trivial.

Here’s that conclusion:

For decades, there has been considerable interest in determining what role, if any, the majority of the DNA in eukaryotic genomes plays in organismal development and physiology. The ENCODE data are only the most recent contribution to a long-standing research program that has sought to address this issue. However, evidence casting doubt that most of the human genome possesses a functional role has existed for some time. This is not to say that none of the nonprotein-coding majority of the genome is functional—examples of functional noncoding sequences have been known for more than half a century, and even the earliest proponents of “junk DNA” and “selfish DNA” predicted that further examples would be found. Nevertheless, they also pointed out that evolutionary considerations, information regarding genome size diversity, and knowledge about the origins and features of genomic components do not support the notion that all of the DNA must have a function by virtue of its mere existence. Nothing in the recent research or commentary on the subject has challenged these observations.

The whole ENCODE debacle, in which hundreds of millions of dollars was sunk into an effort to identify the function of every bit of the genome, was a PR disaster. Larry Moran asks how Nature magazine dealt with the errors; the answer seems to be with denial. Authors of the ENCODE report are claiming they were “misunderstood & misreported” and that they aren’t “backing away from anything”.

I’m not too dismayed that science journalists didn’t understand how the claims of ENCODE conflicted with evolutionary biology, since I don’t expect journalists to have the same focus on the science (this is not a knock on science journalism; I have a lot of respect for the good practitioners of the art, but just that they have different priorities than the working scientists who have to deal with the background details). But what really shocks me is that big-name genomics researchers, people who get awarded lots of money to study the structure of the genome, don’t understand the fundamentals laid out for them in the Palazzo & Gregory paper. It’s not that I expect every scientist to know the entirety of a gigantic field — heck, I get confused and lost every time I read a bioinformatics paper — but these are scientists paid in big money and prestige to study genome function who don’t have a grasp on the evolutionary constraints on genome function, which seems to be a rather critical omission. And these scientists without a clue get elected to the Fellowship of the Royal Society.

How does that happen? I had this fantasy that science was a meritocracy and that great scientists advanced by having deep knowledge and doing great work, but it seems another way to succeed is leap into a new field and bamboozle everyone with technology.

I am so disillusioned.