Czytaj książkę: «The Language of the Genes»

Introduction THE FINGERPRINTS OF HISTORY

In 1902, in Paris, a horrible murder was solved by the great French detective Alfonse Bertillon. He used a piece of new technology which struck fear into the heart of the criminal community. Eight decades later two young girls were killed near the Leicestershire village of Narborough. Again, the murderer was found through a technical advance, although the machinery involved would have been beyond the comprehension of Bertillon. These events link the birth and the coming-of-age of human genetics.

The Parisian killer was trapped because he left a fingerprint at the scene of the crime. For the first time, this was used in evidence as a statement of identity. The idea came from ancient Japan, where a finger pressed into a clay pot identified its maker. The Leicestershire murderer was caught in the same way. A new test looked for individual differences in genetic material. This ‘DNA fingerprint’ was as much a statement of personal uniqueness as Bertillon’s clue or the potter’s mark. As usual, life was more complex than science. The killer, a baker called Colin Pitchfork, was caught only after DNA fingerprints had eliminated a young man who had made a false confession and after Pitchfork had persuaded a friend to give a fraudulent blood sample under his name.

The idea that fingerprints could be used to trace criminals came from Charles Darwin’s cousin, Francis Galton. He founded the laboratory in which I work at University College London, the first human genetics institute in the world. Every day I walk past a collection of relics of his life. They include some rows of seeds that show similarities between parents and offspring, an old copy of The Times and a brass counting gadget that can be hidden in the palm of the hand. Each is a reminder of Galton. As well as his revolution in detective work Galton was the first person to publish a weather map and the only one to have made a beauty map of Britain, based on a secret ranking of the local women on a scale of one to five (the low point, incidentally, being in Aberdeen).

His biography reveals an unrelieved eccentricity, well illustrated by the titles of a dozen of his three hundred scientific papers: On spectacles for divers; Statistical inquiries into the efficacy of prayer; Nuts and men; The average flush of excitement; Visions of sane persons; Pedigree moths; Arithmetic by smell; Three generations of lunatic cats; Strawberry cure for gout; Cutting a round cake on scientific principles; Good and bad temper in English families; and The relative sensitivity of men and women at the nape of the neck. Galton travelled much in Africa, regarding the natives with some contempt and measuring the buttocks of the women using a sextant and the principles of surveying.

Galton’s work led, indirectly, to today’s explosion in human genetics. His particular interest was in the inheritance of genius (a class within which he placed himself). In his 1869 book Hereditary Genius, he investigated the ancestry of distinguished people and found a tendency for talent to crop up again and again in the same family. This, he suggested, showed that ability was inborn and not acquired. Hereditary Genius marked the first attempt to establish patterns of human inheritance with well-defined traits – such as becoming (or failing to become) a judge rather than with mere speculation about vague qualities such as fecklessness.

Galton and his followers would be astonished at what biology can now do. It still does not understand attributes such as genius (and reputable scientists hardly concern themselves with them), but DNA is much involved in mental and physical illness. Half a million DNA samples have been taken by police in Britain since the test was invented, and the government has a scheme to follow the genes – and the ailments – of the same number of its citizens over two decades in the hope of finding the biological errors responsible for killers like cancer and heart disease. New tests mean that parents can sometimes choose whether to risk the birth of a child with an inborn defect. Ten thousand such illnesses are known and if we include, as we should, all ailments with an inherited component, most people die because of the genes they carry.

Genetics does more than reveal fate. Humans share much of their heritage with other creatures. As Galton himself illustrated with the appropriate impression pasted near that made by Gladstone, the prime minister, chimpanzees have fingerprints. Now we know that much of their DNA is identical to our own (as indeed is that of bananas). All this suggests that humans and apes are close relatives.

Genetics is the key to the past. As every gene must have an ancestor, inherited diversity can be used to piece together a picture of history more complete than from any other source. Each segment of DNA is a message from our forebears and together they contain the whole story of human evolution. Everyone alive today is a living fossil and carries within themselves a record that revisits the birth of humankind. The Origin of Species expresses the hope that ‘light will be thrown on the origin of man and his history’. Darwin’s hint that humans share a common descent with all other creatures is now accepted by all scientists, because of the evidence of the genes.

Evolution, the appearance of new forms by the alteration of those already present, is no more than descent with modification. The same is true of language. As a boy, I was amused by the tale of the order going down the line of command to soldiers in the trenches. ‘Send reinforcements, we’re going to advance’ changed to ‘Send three and fourpence, we’re going to a dance’ as it passed from man to man. This simple tale illustrates how accidents, as an inherited message is copied, can lead to change. Because of mutation, life, too, is garbled during transmission.

This book is about inheritance: about the clues of our past, present and future that we all contain. The language of the genes has a simple alphabet, with not twenty-six letters, but four; the DNA bases – adenine, guanine, cytosine and thymine (A, G, C and T for short). They are arranged in words of three letters such as CGA or TGG. Most code for different amino acids, which are themselves joined together to make proteins, the building blocks of the body.

The economy of life’s language can be illustrated with an odd quotation from a book called Gadsby, written in 1939 by one Ernest Wright: ‘I am going to show you how a bunch of bright young folks did find a champion, a man with boys and girls of his own, a man of so dominating and happy individuality that youth was drawn to him as a fly to a sugar bowl.’ This sounds somewhat peculiar, as does the rest of the fifty-thousand word book, and it is. The quotation, and the whole work, lacks the letter ‘e’. An English sentence can be written with twenty-five letters instead of twenty-six, but only just. Biology manages with a mere four.

Although its vocabulary is simple the genetical message is very long. Each cell in the body contains about six feet of DNA. There are so many cells that if all the DNA in a single human body were stretched out it would reach to the moon and back eight thousand times. Twenty years ago, the Human Genome Project set out to read the whole of its three thousand million letters, and to publish perhaps the most dreary volume ever written, the equivalent of a dozen or so copies of the Encyclopaedia Britannica. The task is now more or less complete. The sequencers followed a grand scientific tradition: the Admiralty, after all, sent the Beagle to South America with Darwin on board not because they were interested in evolution but because they knew that if they were to understand (and, with luck, control) the world, the first step was to map it. The chart of the genes, like that of the Americas, has been expensive to make; but – like the theory of evolution itself – it may change our perception of ourselves.

Powerful ideas like inheritance and evolution soon attract myths. Impressed by his studies of genius, Galton founded the science (if that is the right word) of eugenics. Its main aim was ‘to check the birth rate of the Unfit and improve the race by furthering the productivity of the fit by early marriage of the best stock’. He led the new field of human genetics into a blind alley from which it did not emerge for half a century. At his death, he left £45,000 to found the Laboratory of National Eugenics at University College London and, in fine Victorian tradition, £200 to his servant who had worked for him for forty years. His research institute soon changed its name to the Galton Laboratory to escape from the eugenical taint. What became of his servant is not recorded.

Galton’s social ideas and Darwin’s evolutionary insights had a pervasive effect on the intellectual history of the twentieth century. They influenced left and right, liberal and reactionary, and continue – explicitly or otherwise – to do so. Many disparate figures trace their ideas to The Origin and to Hereditary Genius. All are united by one belief: in biology as destiny, in the power of genes over those who bear them.

The most famous monument in Highgate Cemetery in London, a couple of miles north of today’s Galton Laboratory, is that of Karl Marx. Its inscription is well known: ‘Philosophers have only interpreted the world. The point, however, is to change it.’ Darwinism was soon used in an attempt to live up to that demand. The philosopher Herbert Spencer, buried just across the path from Marx, founded what he called Social Darwinism; the notion that poverty and wealth are inevitable as they reflect the biological rules that govern society. In his day, Spencer was famous. His Times obituary claimed that ‘England has lost the most widely celebrated and influential of her sons.’ Now he is remembered only for that neatly circular phrase ‘the survival of the fittest’ and for inventing the word ‘evolution’.

He wrote with a true philosopher’s clarity: ‘Evolution is an integration of matter and concomitant dissipation of motion; during which matter passes from an indefinite, incoherent homogeneity, to a definite, coherent heterogeneity, through continuous differentiations and integrations’. Those lucid lines were parodied by a mathematical contemporary: ‘A change from a nohowish, untalkaboutable all-alikeness to a somehowish and in general talkaboutable not-all-alikeness by continuous somethingelsifications and sticktogetherations.’

Spencer used The Origin of Species as a rationale for the excesses of capitalism. The steel magnate Andrew Carnegie was one of many to be impressed by the idea that evolution excuses injustice. He invited Herbert Spencer to Pittsburgh. Unfortunately, the philosopher’s response to his trip to see his theories worked out in steel and concrete was that ‘Six months’ residence here would justify suicide.’

Galton, too, supported the idea of breeding from the best and sterilising those whose inheritance did not meet with his approval. The eugenics movement joined a gentle concern for the unborn with a brutal rejection of the rights of the living (a combination not unknown today). Galton’s main interest in genetics was as a means to forestall the imminent decline of the human race. He claimed that families of ‘genius’ had fewer children than most and was concerned about what this meant for the future. It was man’s duty to interfere with his own evolution. As he said: ‘What Nature does blindly and ruthlessly, man may do providently, quickly and kindly.’ Perhaps his own childless state helped to explain his anxiety.

Many of the eugenicists shared the highly heritable attributes of wealth, education and social position. Francis Galton gained his affluence from his family of Quaker gunmakers. Much of his agenda was the survival of the richest. Other eugenicists were on the left. They felt that if economies could be planned, so could genes. George Bernard Shaw, at a meeting attended by Galton in his last years, claimed that ‘Men and women select their wives and husbands far less carefully than they select their cashiers and cooks.’ Later, he wrote that ‘Extermination must be put on a scientific basis if it is ever to be carried out humanely and apologetically as well as thoroughly.’ Shaw was, no doubt, playing his role as Bad Boy to the Gentry, but subsequent events made his tomfoolery seem even less droll than it did at the time.

Sometimes, such notions were put into practice. Paraguay has an isolated village with an unusual name: Nueva Germania, New Germany. Many of its inhabitants have blonde hair and blue eyes. Their names are not Spanish, but are more likely to be Schutte or Neumann. They are the descendants of an experiment; an attempt to improve humankind. Their ancestors were chosen from the people of Saxony in 1886 by Elisabeth Nietzsche – sister of the philosopher, who himself uttered the immortal phrase ‘What in the world has caused more damage than the follies of the compassionate?’ – as particularly splendid specimens, selected for the purity of their blood. The idea was suggested by Wagner (who once planned to visit). The New Germans were expected to found a community so favoured in its genetic endowment that it would be the seed of a new race of supermen. Elisabeth Nietzsche died in 1935 and Hitler himself wept at her funeral. Today the people of Nueva Germania are poor, inbred and diseased. Their Utopia has failed.

The eugenics movement had an influence elsewhere in the New World. In 1898, Charles Davenport, then professor of evolutionary biology at Harvard, was appointed as Director of the Cold Spring Harbor Laboratory on Long Island Sound. Initially, the Laboratory concentrated on the study of ‘the normal variation of the animals in the harbor, lakes and woods, and the production of abnormalities’. It carried out some of the most important work in early twentieth-century biology.

Soon, Mrs E H Harriman, widow of the railway millionaire, decided to devote part of her fortune to the study of human improvement. The Eugenics Record Office was built next to the original laboratory. It employed two hundred field workers, who were sent out to collect pedigrees. Their 750,000 genetic records included studies of inherited disease and of colour blindness; but also recorded the inheritance of shyness, pauperism, nomadism, and moral control.

Davenport’s work had an important effect on American society. The first years of the twentieth century saw eugenical clubs with prizes for the fittest families and, for the first time, medicine became concerned about whether its duty to the future outweighed the interests of some of those alive today. In Galtonian style, Davenport claimed that: ‘Society must protect itself; as it claims the right to deprive the murderer of his life so also may it annihilate the hideous serpent of hopelessly vicious protoplasm.’ Twenty-five thousand Americans were sterilised because they might pass feeble-mindedness or criminality to future generations. One judge compared sterilisation with vaccination. The common good, he said, overrode individual rights.