Discovering the Double Helix

Question: What was the key breakthrough that led to the discovery of DNA?

James Watson: Well, there were two.  A methodological one, where we borrowed from Linus Pauling, that the most direct route to the structure was building molecular models as opposed to trying to deduce the structure entirely from x-ray defraction data.  There was a decision that Crick and I made in October, 1951. 

The second was the realization that the data of Erwin Chargaff showing similar amounts of adenine and thymine and timing and of guanine and cytosine indicated that they must be paired to each other in the DNA structure.  Once you had that, in fact the structure followed within several weeks. 

Question: Did your inability to find a date at Cambridge contribute to your discovery of DNA?

James Watson: The best thing that ever happened to me was I didn’t find a date because that would have... you know, the right girl I would have found more interesting than the, you know.  If I had a girl to play tennis or something, I would have preferred doing that than just, you know, thinking about DNA.  Whereas my great advantage was, I was at the time the only person truly obsessive about DNA.  And you know, so many people were just obsessive about some unrealized you know, emotional problem.  So at Cambridge University, I mean, today Cambridge University is filled with, you know, well-dressed, attractive, intelligent girls.  The two Cambridge colleges when I was there, the girls were out of town, we virtually never saw them and you know.  It was just lucky it was for a later time in my life.

Question: Have you been happy with the progress in molecular biology since you discovered DNA?

James Watson: Well, initially I wanted to you know, move on from the structure of DNA to RNA and that didn’t seem to fall out, so that was a disappointment.  But on the whole, it was that everything occurred faster than we thought it would.  That you know, we had the genetic code, the first details in '61, and its completion by '66.  That was only 13 years.  And I never thought it would go so fast. 

And then, I never even dreamed, you know, that we would be able to sequence long stretches of DNA. You would actually see the structure of specific genes.  Then we were likely thinking in terms of small viruses because we knew they contained only several genes.  And so maybe the ultimate would be to some day work out the structure of a sequence of a virus containing several thousand letters.  But once it started it just has moved, you know, with always... You know, we had the method before we almost had the questions to ask about what we were seeing. 

Recorded on September 28, 2010
Interviewed by Paul Hoffman

The pioneering molecular biologist recounts some of the major breakthroughs in the search for the structure of DNA.

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