Modern Mind

another enzyme, known as Hinfl, which separates out the ribbons of DNA that contain the repeated sequences. Finally, by a process known as electrophoresis, the DNA fragments were sorted into bands of different length and transferred to nylon sheets, where radioactive or luminescent techniques obtained images unique to individuals. 3
    Jeffreys was called in to try this technique with Richard Buckland. He was sent samples of semen taken from the bodies of both Lynda Mann and Dawn Ashworth, together with a few cubic centimetres of Buckland’s blood. Jeffreys later described the episode as one of the tensest moments of his life. Until that point he had used his technique simply to test whether immigrants who came to Britain and were admitted on the basis of a law that allowed entry only to close relatives of those already living in the country really were as close as they claimed. A double murder case would clearly attract far more attention. When he went into his lab late one night to get the results, because he couldn’t bear hanging on until the next morning, he got a shock. He lifted the film from its developing fluid, and could immediately see that the semen taken from Lynda and Dawn came from the same man – but that killer wasn’t Richard Buckland. 4 The police were infuriated when he told them. Buckland had confessed. To the police mind, that meant the new technique had to be flawed. Jeffreys was dismayed, but when an independent test by Home Office forensic experts confirmed his findings, the police were forced to think again, and Buckland was eventually acquitted, the first person ever to benefit in this way from DNA testing. Once they had adjusted to the surprising result, the police mounted a campaign to test the DNA of all the men in the Narborough area. Despite 4,000 men coming forward, no match was obtained, not until Ian Kelly, a baker who lived some distance from Narborough, revealed to friends that he had taken the test on behalf of a friend, Colin Pitchfork, who
did
live in the vicinity of the village. Worried by this deception, one of Kelly’s friends alerted the police. Pitchfork was arrested and DNA-tested. The friend had been right to be worried: tests showed that Pitchfork’s DNA matched the semen found on Lynda and Dawn. In January 1988, Pitchfork became the first person to be convicted after genetic fingerprinting. He went to prison for life. 5
    DNA fingerprinting was the most visible aspect of the revolution in molecular biology. Throughout the late 1980s it came into widespread use, for testing immigrants and men in paternity suits, as well as in rape cases. Its practical successes, so soon after the structure of the double helix had been identified, underlined the new intellectual climate initiated by techniques to clone and sequence genetic material. In tandem with these practical developments, a great deal of theorising about genetics revised and refined our understanding of evolution. In particular, much light was thrown on the stages of evolutionaryprogress, working forward from the moment life had been created, and on the philosophical implications of evolution.
    In 1985 a Glasgow-based chemist, A. G. Cairns-Smith, published
Seven Clues to the Origin of Life. 6
In some ways a maverick, this book gave a totally different view of how life began to the one most biologists preferred. The traditional view about the origins of life had been summed up by a series of experiments carried out in the 1950s by S. L. Miller and H. C. Urey. They had assumed a primitive atmosphere on early Earth, consisting of ammonia, methane, and steam (but no oxygen – we shall come back to that). Into this early atmosphere they had introduced ‘lightning’ in the form of electrical discharges, and produced a ‘rich brew’ of organic chemicals, much richer than had been expected, including quite a large yield of amino acids, the building blocks for the nucleic acids which make up DNA. Somehow, from this rich brew, the ‘molecules of life’ formed. Graham Cairns-Smith thought this view nonsense because DNA molecules are extremely complicated, too complicated architecturally and in an engineering sense to have been produced accidentally, as the Miller-Urey reactions demanded. In one celebrated part of his book, he calculated that for nucleotides to have been invented, something like 140 operations would have needed to have evolved
at the same time,
and that the chances of this having occurred were one in