Fifty Years Of The Double Helix

THE picture of the double helix, the structure of the DNA, has today become the icon of science, replacing the earlier one of the atom, tainted now by its association with nuclear weapons. And this week, the discovery of the chemical structure of life, the DNA structure of the Double Helix is 50 years old. Watson and Crick first hit upon this structure on February 28, 1953. The paper that James Watson and Francis Crick published subsequently in Nature, April 25 titled “Molecular Structure of Nucleic Acids” will remain as one of the definitive moments in the history of science.

The future of genetics and its benefits are mired in deep controversy. Genetically modified foods have come up against stiff resistance as also the fear of unintentionally letting loose a new and deadly disease. There are also ethical concerns regarding human cloning and bioengineering the human genome itself. Alongside, we also have the continuation of the earlier debate of Nature vs. Nurture, with genetic fundamentalists using genes to explain all traits — from intelligence to disease. Watson, the co-discoverer of DNA structure has recently even suggested genetic engineering should be used to remove stupidity and “make all girls pretty,” drawing sharp criticism both from an ethical standpoint as well as Watson’s understanding (or lack of it) of how genes work.

Not only the future of genetics is open to controversy, even its past is not free from it. Central to the discovery of DNA structure was a key X-ray photograph of a DNA molecule that Rosalind Franklin had taken. Maurice Wilkins, her colleague in Kings College, who did not get along with her, showed this to Watson without either her permission or knowledge. Neither Watson nor Crick acknowledged Franklin’s role in their discovery, though Watson was to write later that the X-ray picture was what opened his eyes to the DNA structure being a double helix. Worse, Watson in his book, The Double Helix (1968), not only underplayed Franklin’s role, but wrote disparagingly, calling her “Rosy” and implying that she was a Gorgon of a lady and extremely difficult to work with. He wrote, “Clearly Rosy had to go or be put in her place.” Later, he added, “The thought could not be avoided that the best home for a feminist was in another person’s lab.”  According to Brenda Maddox, in her biography “Rosalind Franklin: the Dark Lady of DNA” has suggested convincingly that Watson portrayed her as hostile and unreasonable to justify his stealing of her data with the connivance of Maurice Wilkins. Watson Crick and Wilkins went on to get the Nobel prize in 1962, a prize Rosalind Franklin could not have shared in any case as she died in 1958 aged 37 of ovarian cancer. Nobel is not given posthumously. But deliberate omission of Rosalind Franklin had much to do with the almost male world of British science, which did not permit women to close the threshold. It was not an accident that Franklin left King’s College to join J D Bernal in his laboratory; Bernal was a communist and far more egalitarian in his lab then what was prevailing elsewhere.

The race for discovering the DNA structure was an intense one with Linus Pauling, later to get the Nobel Prize twice — once for chemistry and once for peace — as the clear front-runner. The King’s College had Maurice Wilkins and Rosalind Franklin who were photographing diffraction patterns by bombarding powdered DNA molecules with X-rays. Crick and Watson did no experiments themselves but build models of the DNA structure. They had come up earlier (1951) with a three-chained model of the DNA structure that was found to be wrong. Linus Pauling in 1952 announced that he had determined the structure of the DNA. However, he also had 3 chains, which Crick and Watson knew to be incorrect, themselves having traversed that path. Franklin’s photograph made clear to Watson that DNA consisted of two spiral chains, running parallel to each other but in opposite directions. Watson and Crick also found that two combinations of four bases – adenine-thymine (A-T) and guanine-cytosine (G-C) lined up in a way that they could hook together in the space between the sugar phosphate spiral chains. Thus was born the familiar spiral staircase model of the DNA, with the sugar phosphate ribbons forming the support for the steps, while the steps were the AT and GC pairs. This was the seminal discovery that discovery that Watson and Crick made in 1953 that we are celebrating this week.

The sequence of these bases – the code of AT and GC pairs — makes up the genes. It is the basic code that contains the information for replication of the cell. If we unwind the DNA strand in just 1 person, it would stretch about 600 million miles, about six times the distance from the earth to the sun. In one cell, the DNA strand would stretch for 6 feet.

The DNA research has not only created controversies such as human cloning and genetically modified foods, but also various uses. One of them, DNA fingerprinting, by which each individual can be uniquely identified based on even a tiny amount of DNA material, has had unexpected consequences. A group in the US started the Innocence Project and used DNA evidence to clear 124 person convicted of serious crimes, many of them condemned to the death penalty. In Illinois, the DNA evidence exonerated so many, that Governor George Ryan lost confidence in his state’s justice system and commuted all the death sentences. Incidentally, George Bush remains still a devotee of the death sentence, and in his period as Governor of Texas, carried out a very large number of such sentences. In Argentina, the mothers of those who were secretly killed by the military regime, used the DNA evidence to reclaim their grandchildren who had been “adopted” by childless military couples. Nora Cortinas, one of the leaders of this movement – the Mothers of Mayo Plaza, who had lost her own son, was in the Asian Social Forum in Hyderabad this January.

Perhaps the most important work in genetics has been mapping the human genome. The project was proposed by many scientists in the US, but really gathered steam when Watson joined the project in 1990. He quit the project when he found the then Director of National Institute of Health was patenting genes. The human genome project, initially housed in NIH in the US, later became an international effort, with many countries and laboratories joining in. By this time, a private company set up by Craig Venter, who first sequenced a single celled organism, had also joined the race. Finally, the two groups shared their knowledge and announced their results in the same time, one in Nature and the other in Science, in February 2001.

The results of the Human Genome project not only produced the first draft of the gene sequences but also showed that the number of genes were much lower than the 140,000 that it was supposed to contain. The final tally was closer to 30,000. While at first sight this may be considered only a question of numbers, it has profound implications. There are just not that many genes that would explain various facets of human personality. Worse, the number of genes that human beings share with lower mammals such as mice, make it very unlikely that human nature is a product of just genes expressing themselves. The ideological world of free market of course loves genetic determinism. According to the free market ideologues, genes explain the status quo completely. This genetic fundamentalism, flowing out of geneticists such as Richard Dawkins and socio-biologists such Edward Wilson, now comes up against hard evidence that there are not enough codes in the genome to programme human nature. The cultural component of human development is what decides the way we behave. Venter, in his 2001 Press Conference announcing the sequencing of the Genome had said, “The small number of genes—30,000 instead of 140,000—supports the notion that we are not hard wired. We now know that the notion that one gene leads to one protein and perhaps one disease is false.”

Further, Venter continued, “We now know that the environment acting on these biological steps may be key in making us what we are. Likewise, the remarkably small number of genetic variations that occur in genes again suggest a significant role for environmental influences in developing each of our uniqueness.” In the Nature versus Nurture debate, in which IQ to criminal behaviour has all been attributed by some to genes and heredity, the genome’s unravelling gives a clear refutation of the Nature position. On the question of race, in his Press Note Venter had said, “We are confident that our sequence will help to demonstrate that the human genome will not aid those who want to perpetuate racial prejudice.” Neither is it likely to help those who propose that the elite in society are those who have more intelligence coded in their genes.

The change of only a few genes has resulted in the growth of the brain, rise of speech and tool making abilities in human beings. It is sobering and enormously humbling for human beings to know that they have arisen from a few genetic accidents. The complexities of human civilisation thus lie in enabling cultural evolution to take place rather than the earlier expectation of a long history of physical evolution. Human uniqueness lies not in our genes but in our culture. This explains the enormous changes in how we live today, a result of our cultural evolution of the last 150,000 years.

While hailing the 50 years of development that started with the Double Helix, we must end on a note of caution. Today, the ethical questions such as should human cloning be allowed, should we allow genetic engineering to produce designer babies have to be addressed along with real dangers — either intentionally or by accident – of producing dangerous pathogens or producing super pests and new exotic species that crowd out other species. While it is impossible to stop the growth of knowledge, just as King Canute could not stop the waves, we have to develop not only the maturity of a civilisation that can handle such questions and dangers, but also a just and equitable social order. Whether we will get drugs at astronomical prices, with all genetic knowledge patented by the drug companies, while a large part of the population languishes without health care as it is uninsurable due to genetic “defects”, depends on what kind of society we want to build. The answer here does not lie in our genes but in ourselves. To Paraphrase Marx, it is men (and women) who make history. Not genes. This is what 50 years of the Double Helix has now made clear.