As textbooks would have it, the term “junk DNA” was coined in 1972 by Susumu Ohno as part of his work on the role of gene and genome duplication. I met Susumu Ohno at a meeting in Crete many years ago, and the way I understood what he told me was that he “deliberately” chose a “provocative term” to emphasize the “uselessness” of this DNA fraction.
I no longer believe this historical “narrative.”
It all started with my obsession to read very thoroughly every article that I quote, instead of relying on indirect references. In this day and age, in which articles are signed by hundreds of authors, the vast majority of whom don’t even bother to read their “work,” I stand out like a nigella seed in mayonnaise. This disorder is probably due to my association with Mina Graur, who is a historian that only trusts “primary sources.” Indeed, so strong is her belief in primary sources, that I am quite certain she wouldn’t even trust a textbook description of the double helix—she would want to read Watson and Crick’s (1953) article, as well as their notebooks, correspondences, and preliminary drafts, and if possible interview each and every one associated with the lab in Cambridge including the janitors. What can I say? She does NOT trust “secondary” sources!
For a while now, I became entangled in a bitter fight with the ENCODE gang over “junk DNA,” and to my dismay, I realized that I cannot find a copy of Susumu Ohno’s (1972) article “So much ‘junk’ DNA in our genome.” So, I started searching the net for the article. My searches led me to discover three publications from 1972 that mention “junk DNA.” The above mentioned paper by Susumu Ohno, a book chapter by David Comings, and a New Scientist commentary by Tim Hunt.
Where did Comings and Hunt get their “junk DNA” from? Solving the origin of Comings’ “junk DNA” was easy. He got it from Susumu Ohno, as he quotes two “in press” papers by Ohno. The origin of Tim Hunt’s “junk DNA” proved to be much more interesting.
In 1972, Tim Hunt was a 29-year-old researcher at Cambridge trying to understand messenger RNA and the great amounts of DNA that never produce mRNA. In time, his research led him into a different area of study, and in 2001, Tim Hunt shared the Nobel Prize in Physiology or Medicine with Paul Nurse and Leland H. Hartwell. The work for which he was conferred the highest accolade in the sciences had nothing to do with either mRNA or junk DNA—the Nobel was in recognition of his discovery of proteins that control cell division.
In his 1972 commentary, Tim Hunt uses the term “junk DNA” to refer to “the large amount of nucleic acid that never finds its way out of the nucleus, which does not fit in with the old categories of genes and messages.”
Where did Tim Hunt get the term? I sent him an email.
“I have recently realized that although the late Susumu Ohno is credited solely with the coinage “junk DNA,” he was not the only person to have used the term in 1972. In your “How mammals get the message” in New Scientist, you have an entire section entitled
“Why all that junk?” In this section you mention “junk DNA.” I am curious whether (1) you got the term from Susumu Ohno, (2) he got it from you, (3) you coined it independently, or (4) you got it from a third person. I would greatly appreciate your help with this historical puzzle.”
The reply by Dr. Hunt was surprising.
“Gosh, yes! I did write that piece, and I never met Ohno. I got it from Sydney Brenner and/or Francis Crick—it was certainly current in Cambridge at the time. Maybe they got it from Ohno? You should ask Sydney.”
So, I wrote Dr. Brenner. The first sentence of his reply made the puzzle even more profound.
“I can confirm that we were using the idea of “junk” in the genome in the sixties in Cambridge.”
Really? The sixties? If the term was indeed current in the sixties, it is entirely possible that the term may have found its way into the literature and hasn’t been detected thus far. If it was there, I was determined to find it.
Enter Google Ngram Viewer, with which one can find short phrases in over 5.2 million books (published between 1500 and 2008) that have been digitized by Google.
With Google Ngram, I struck gold, a 1963 paper by Charles Ehret and Gérard de Haller entitled “Origin, development, and maturation of organelles and organelle systems of the cell surface in Paramecium.” The paper which was published in Journal of Ultrastructure Research is huge—42 pages and 86 figures. On page 39 it is written:
“While current evidence makes plausible the idea that all genetic material is DNA (with the possible exception of RNA viruses), it does not follow that all DNA is competent genetic material (viz. ‘junk’ DNA), nor that all Feulgen-positive material is active DNA.”
This was completely unexpected. Nine years before Susumu Ohno, two authors wrote about “junk DNA” in a casual manner without even bothering to explain what junk DNA is. I have never heard of the authors before. Who was Charles F. Ehret? Who was Gérard de Haller?
A little more digging revealed that Charles F. Ehret was an important person, as evidenced by the fact that The Washington Post published an obituary on his death in 2007.
“Charles F. Ehret, 83, a scientist whose study of circadian rhythms led to a widely popular anti-jet lag regimen that improved the trips of untold numbers of world travelers, died February 24 of multiple illnesses at his home in Grayslake, Ill.
In more than 35 years of experimentation, Dr. Ehret found that the headaches, nausea, disorientation, fatigue and malaise suffered by globe-trotters had almost nothing to do with thin air and the dizzying effects of supersonic speed, as was commonly assumed. Rather, jet lag is a matter of crossing too many time zones too quickly for the body to adjust. It can be ameliorated by adjusting eating, activity and sleep schedules according to a strict system that Dr. Ehret developed.”
A search of the literature revealed that the Journal of Ultrastructure Research paper represented quite a detour in the scientific life of Dr. Ehret. With the exception of a 1948 paper in The Anatomical Record, entitled “The mating reaction of multimicronuclear monstrosities in Paramecium bursaria,” his entire research program dealt with circadian rhythms, jet lag, and light exposure.
Interestingly, Dr. Ehret worked on many different organisms which, according to The Washington Post, included “single-celled organisms, rats, his eight children, and volunteers.” Rats and eight children… what a winning combination!
The amount of information I could find on Gérard de Haller is quite minimal. He became Professor of Protistology at the University of Geneva in 1969. He mostly published in French, and the last known address for him was the Molecular Systematics Group at the University of Geneva. As far as I could ascertain, he published his last paper in 1993.
How should we, then, present the historical background of “junk DNA” in textbooks? I am quite certain that Ehret and de Haller did not invent the term. They used it properly, but it wasn’t theirs. At this point and in the absence of new information, the following paragraph may be appropriate.
“The term ‘junk DNA’ became popular in the 1960s (e.g., Ehret and de Haller 1963). It was formalized by Susumu Ohno in 1972.”
In the manner of the appeals by Oxford English Dictionary, I would like to ask the readers: Do you have an earlier record of the term “junk DNA”? Please submit your evidence by email.
From left to right: Ohno, Hunt, Comings, Brenner, Crick, and Ehret. (I would greatly appreciate receiving a picture of Gérard de Haller.)