There’s a very cool paper in the latest issue of Science that pinpoints a particular chunk of DNA that may have played a role in the evolution of a human-like hand from the hands of our primate ancestors. Not Exactly Rocket Science has the details. For some reason, a number of articles on the paper are using the hook that this segment of DNA was once dissed as junk. “A patch of DNA once regarded as ‘junk’ may hold the key to upright walking and opposable thumbs,” according to Wired. These reports seem to be following the language from the original press release.
The “Wow! Junk DNA is not junk after all” news hook is a tempting one, but it needs to be resisted. At the very least, science writers need to recall some history.
Less than two percent of the human genome consists of protein-coding genes. The “junk DNA” the news reports are referring to is the other 98%. But in the late 1950s, researchers discovered that short segments of DNA near protein-coding genes in E. coli played important functions. Proteins could clamp onto those segments to shut a gene down or to ramp up the production of the corresponding protein. In other words, scientists already knew fifty years ago that some segments of DNA that did not encode proteins were useful. This was not obscure research: the scientists got the Nobel prize. No big secret there.
The new paper about hand evolution reports on the discovery of a special kind of DNA segment called an enhancer. An enhancer sits very far away from the gene it enhances. But if DNA is folded in on itself, the two come close together. Proteins that clamp down on the DNA can then increase the production of the gene’s protein.
So, are enhancers an amazing new kind of junk that’s not junk?
Nope. The first reports of enhancers came out in 1981, 27 years ago.
In other words, scientists have known for a long time that at least some parts of the genome that are not protein-coding genes served a function. The particular kind of DNA that was discovered to play a role in the development of hands has been familiar to biologists for nearly three decades. It comes as no surprise that there are more enhancers to be discovered in the human genome. They’re just hard to find, because they’re so short and so far from the genes they enhance.
Those who do not know their science history are doomed to repeat bad news hooks.
(For more on this history, see this post at Genomicron.)
September 5th, 2008 at 3:52 pm
Very well stated.
September 5th, 2008 at 8:07 pm
Yep. Plenty of DNA has regulatory function.
September 5th, 2008 at 8:57 pm
This should be required reading for every science journalist. It’s kind of appalling that so many articles seem to be written without even the basic knowledge that is found in introductory biology texts.
September 8th, 2008 at 5:18 am
So, I get the impression that many of the “Science Journalists” are not actually science journalists, but editors re-writing press releases. As an aspiring science writer myself, when I practice my writing I like to go to the original source of science news (an original paper.) Do you think that a majority of science journalists are just taking shortcuts?
There are notable exceptions, of course, but it appears to me that many science journalists don’t have any more of a background in science than they do in politics. I don’t know of any schools that focus on science in their mass communications programs. Considering how the assignment desk works, I imagine that most of the people that are science writers were writing about something else until a copy editor says “Hey, Johnson, here’s something from the wire that looks interesting about junk DNA. Give me a piece on it by deadline.” Suddenly, Johnson is the “science writer” for the paper or the magazine.
I’m not saying that science writers should be required to have PhD’s, but I am saying that with the media as it is, there is no wonder that accurate science journalism is a problem. It would be nice to be able to say “Here’s a great story, read up on the background of DNA and check out the literature and if it has new information that sheds light on regulator genes give me a piece by next week.” With the budgets for writers being continually cut at the major dailies, I don’t see this happening too much.
September 8th, 2008 at 10:56 am
I haven’t read too much of the coverage of this paper. But like it or not, most of the public is not familiar with conserved non-coding DNA, nor introns (or exons), nor microRNAs, not even promoters.
I included “junk” (within quotes) in my story as a cue to readers that conserved non-coding sequences were something they’ve heard of before. I’m sure some of my readers are familiar with CNSs, but I’d bet dollars to doughnuts that most aren’t.
Perhaps this perpetuates the myth that our genomes are full of biochemical detritus, but I doubt it.
September 8th, 2008 at 5:42 pm
[...] Science Writers Need Science History By Carl Zimmer There’sa very cool paper in the latest issue of Science that pinpoints a particular chunk of DNA that may have played a role in the evolution of a human-like hand from the hands of our primate ancestors. Not Exactly Rocket Science has … The Loom – http://blogs.discovermagazine.com/loom [...]
September 9th, 2008 at 2:18 pm
In response to Mike Haubrich, there are a number of journalism/writing programs that emphasize science writing and have produced first-rate science writers:
* UCSD’s program for science grad students & postdocs
* MIT’s Writing Program
* Lehigh University-Journalism (environment & risk communication)
* University of Wisconsin
* Johns Hopkins (in Washington, DC)
* Caltech (though it doesn’t have a formal program, it seems to produce a number of science writers)
I agree that it is more likely to be editors than the writers who got the story wrong–unless they are just rewriting the press release.
September 10th, 2008 at 3:55 am
This is not an example of bad science journalism. It may be a tad inaccurate in that the author failed to identify enhancers as non-junk. The fact remains that they discovered a, previously unknown, function of a piece of DNA. We as scientist needs to get off our high horses and not criticize every bit of unimportant detail that isn’t referred correctly. Besides, there is an ongoing scientific debate on “junk” DNA and the inaccuracy is further diminished by that fact. There are far better examples of bad science journalism (like the over-hyping of imminent cures for cancer, diabetes and Alzheimer). Criticize those reports please, not something miniscule like this.
September 17th, 2008 at 9:22 pm
[...] ·Tagged enhancers, junk DNA, science writing Book author and Discover blogger Carl Zimmer criticizes those who wrote about a recent Science paper, saying essentially: “Enhancers aren’t junk [...]
September 19th, 2008 at 6:31 am
[...] Science Writers Need Science History …science writers need to recall some history. [...] In other words, scientists already knew fifty years ago that some segments of DNA that did not encode proteins were useful. [...]
September 27th, 2008 at 12:06 pm
Absolutely! As a historian of medicine, I’m so intrigued by how much we take for granted as “new” when it’s really part of a long historical trajectory. The more we know about this history–the better we can understand our present!
November 11th, 2008 at 1:50 am
[...] few weeks ago Carl Zimmer wrote a nice post at The Loom taking science writers to task for leaping at every chance to grab ahold of the “Wow! [...]
October 8th, 2009 at 2:47 pm
[...] What most biologists call “junk DNA” is primarily made up of repetitive DNA sequences from transposable elements, not [...]