Wednesday, January 02, 2013

The Power of Simple Prose

Sixty years ago this year, Nature published a trio of landmark papers in its April 25 issue. All three were concerned with the structure of DNA, which until then had not been elucidated.

The authors of one of the papers, Watson and Crick [1], won the Nobel Prize, even though their work was based on the efforts of the authors of the other two papers.

Molecular bond structure of DNA. The
pentagonal structures are ribose
moieties. The rungs of the ladder
are purine-pyrimidine pairs.
Few people now remember the papers of Franklin [2] and Wilkins [3], whose work made possible the famous Watson and Crick paper.

Maurice Wilkins began research on the structure of DNA in 1947, at King's College, London. Rosalind Franklin moved to King's four years later to work on the same problem. There was friction, however, between Wilkins and Franklin. Ultimately, Wilkins chose to discuss his frustrations—and laboratory findings—with Cambridge University's Francis Crick and Crick's charismatic young collaborator, James Watson.

On a January 1953 visit to King's, Wilkins showed Franklin's x-ray crystallography data to Watson (without Franklin's knowledge). Rosalind Franklin's work provided incontrovertible evidence of a helical structure for DNA, although (interestingly) she herself didn't believe her results required such a structure.

After meeting with Wilkins, Watson made some quick sketches in the margin of a newspaper, which he later showed to Crick. Four weeks later, Watson and Crick proposed their now-famous model for the structure of DNA.

Ironically, neither Watson nor Crick had worked directly with DNA, and their Nobel Prize winning paper described no lab work. It contained speculations based on the experimental findings of Wilkins and Franklin, and the unpublished work of a number of others.

Rosalind Franklin, whose work
made possible the Watson and
Crick paper, died of ovarian
cancer in 1954, possibly due
to exposure to x-rays in
her laboratory.
When it came to presenting their theories, Watson and Crick had a powerful secret weapon, something completely overlooked by Wilkins and Franklin: good writing.

The Watson/Crick paper was and is a model of exemplary scientific writing. It's brief, clear, simple, and to the point. In fewer than 900 words (half the number used by either Wilkins or Franklin in their papers), Watson and Crick made clear the salient chemical and three-dimensional features of deoxyribonucleic acid, leaving no doubt as to how the double strands of DNA are held together, saying: "The novel feature of the structure is the manner in which the two chains are held together by the purine and pyrimidine bases," and "only specific pairs of bases can bond together. These pairs are: adenine (purine) with thymine (pyrimidine), and guanine (purine) with cytosine (pyrimidine)."

Franklin wrote things like:

For a smooth single-strand helix the structure factor on the nth layer line is given by:

where Jn(u) is the nth-order Bessel function of u, r is the radius of the helix, and R and ψ are the radial and azimuthal co-ordinates in reciprocal space; this expression leads to an approximately linear array of intensity maxima of the type observed, corresponding to the first maxima in the functions J1, J2, J3, etc.

Wilkins wrote things like:

Third, if the nucleotide is extended as an arc of a circle in a plane at right-angles to the helix axis, and with centre at the axis, the intensity of the system of Bessel function layer-line streaks emanating from the origin is modified owing to the phase differences of radiation from the helices drawn through each point on the nucleotide.

Franklin and Wilkins got bogged down in prolix descriptions of their laboratory findings without emphasizing, in spare and elegant fashion, the importance of their findings.

The first paragraph of the Wilkins paper has 74 words contained in three sentences. Franklin's paper starts with 110 words in six sentences. By contrast, the first paragraph of the Watson/Crick paper is just two sentences long:

We wish to suggest a structure for the salt of deoxyribose nucleic acid (DNA). This structure has novel features which are of considerable biological interest.

Watson and Crick thus laid the groundwork for one of the most important scientific papers of all time in just 25 words.

Watson and Crick also knew the value of short paragraphs. Their 843-word paper had 14 paragraphs, total. The papers by Franklin and Wilkins each had 18 paragraphs, but those papers had twice the word count of the Watson/Crick piece.

The secret of genetic reproduction is, of course, implicit in the double-helix structure of DNA, and one would think the implications of this might warrant special discussion in any paper announcing the breaking of the genetic code. What do Watson and Crick do? They throw in a simple one-sentence paragraph: "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material."

Talk about understated. Talk about minimalist.

Three papers; three different approaches. One Nobel Prize.

Is there any better proof of the power of simple, direct language?


1. Watson, J.D., Crick, F.H. A structure for deoxyribose nucleic acid. Nature 1953;171:737–738.[PDF]

2. Franklin, R.E., Gosling, R.G. Molecular configuration in sodium thymonucleate. Nature 1953;171:740–741. [PDF]

3. Wilkins, M.H.F., Stokes, A.R., Wilson, H.R.. Molecular structure of deoxypentose nucleic acids. Nature 1953;171:738–740. [PDF]

If you enjoyed this post, please tweet it, blog it, or simply pass the URL on to a friend. Thanks!