The Language of the Genes

by Steve Jones

  There is a famous anatomical example of the expediency of existence. In all mammals, one of the cranial nerves takes a slight detour around a vertebra in the neck. In giraffes the neck is much extended — but the nerve, far from taking a short cut direct to the brain, goes all the way down to the bottom and back up again. Awkward solutions to an evolutionary dilemma are common and can influence molecules as much as nerves. Perhaps they will explain why most of the structure of DNA also seems to be, to put it bluntly, a shambles.

  When faced with an emergency, people often turn to crude solutions that turn out to be expensive in the long run. Evolution does the same. Some of the protective mechanisms against malaria damage those who use them. When the sickle-cell mutation first appeared it was rare, so that almost every copy was partnered by an unchanged gene. This combination protects against infection and leaves its carriers in good general health. As sickle cell became more common, people with two copies of the altered haemoglobin, one from each parent, appeared. They suffer from sickle-cell anaemia, a severe (and sometimes lethal) ailment. Their red cells collapse even when the parasite has not entered, to give a range of symptoms that include brain damage, heart failure and paralysis. In some places, around one child in ten is born with the condition. That is a high price to pay for protection, but is unavoidable once a population starts using the gene. Some of the other mechanisms (including the thalassaemias) incur the same cost. As more than one person in twenty worldwide carries one or other of these genes, hundreds of thousands of children with inherited anaemias arc born each year. This does not add much weight to the idea of natural selection as a benign designer.

  Other variants which we now see as inborn disease may themselves be, like sickle cell, relics of a defence against infection (perhaps against illnesses which have now disappeared). Sickle-cell anaemia is found in American blacks, who are not exposed to malaria. If its association with infection elsewhere in the world was not known its presence in that racial group would be a mystery. Other ethnic groups have their own inborn illnesses. One Ashkenazi Jew in thirty is a carrier of the gene for Tay-Sachs Disease. Those who inherit two copies suffer from a fatal degeneration of the nervous system. Families who carry this gene may have had ancestors more resistant to tuberculosis than the average. As TB was common in the European ghettos from whence most of them came, Tay-Sachs might perhaps be the relic of a system of protection against infection. The cost is still being paid by their descendants. Other diseases — such as ankylosing spondylitis, or 'poker spine' — tend to strike people who carry certain cell-surface antigens. Perhaps this too is a relic of natural selection by lost diseases.

  Malaria has other attributes which make it a remorseless enemy. Many diseases have been beaten by vaccination. A weakened version of a parasite can persuade the body to produce antibodies which will attack the real thing. The eradication of smallpox is the most spectacular example of this approach. The malaria vaccine has proved a will-of-the-wisp. Plasmodiunt is enormously variable. One of its many surface antigens (which would have to be mimicked by any successful vaccine) exists in fifty different forms. Dozens may be found in just one village. The parasite's sex life makes things worse. Several genes, scattered all over its fourteen chromosomes, produce cell-surface antigens. Every time Plasmodium has sex, they are reshuffled into new and unique combinations. Many patients with malaria are infected with more than one strain, so that new mixtures appear all the time. It will be many years — if ever — before malaria goes the same way as smallpox. It is such a subtle and effective opponent that the genes that protect against it will be needed for a long time yet.

  Disease may say more about human diversity. Even the ABO blood groups system might result from its actions. The A and B variants differ in just seven bases in the thousand or so that code for them; O has a single DNA base missing part-way down the message, which scrambles all the text from there onwards and removes part of the cell-surface structure coded for by this gene. AB individuals have some protection against childhood diarrhoea and, more important, against cholera, while those with O are more susceptible to that infection (but might be more resistant to malaria). Other genes, too, seem to be associated with resistance. Perhaps ancient illnesses explain a lot of our diversity. Nevertheless, plenty of infections have gone for ever. Optimists claim that the conquest of disease, cold and starvation means that natural selection has come to an end. If evolution has one rule, it is to expect the unexpected. New pestilences may appear and cause as much damage as malaria, or those that seem near extinction will stage a resurgence, as has malaria itself.

  The history of the battle against disease says useful things about natural selection. Far from designing a simple and effective protection, whenever a straw appears, it is clutched at. Selection acted like a handyman rather than a craftsman. Its products often seem badly, not to say extravagantly, planned and roughly made. If man is indeed made in God's image, malaria does not say much for divine engineering. This haphazard approach has its strengths. Used by engineers or computer programmers it can make subtle and unexpected things. The logic of selection is that of the living world: to produce a complicated design without a designer.

  Natural selection has never in its three-billion-year history produced a wheel, let alone a work of art; although it has managed to generate eyes, brains and other organs of great complexity. This is because of its grearest weakness, its plodding approach. A wheel, or a watch, needs some long-term ideas. To make either demands an intellectual leap that is beyond evolution. Natural selection has superb tactics, but no strategy — but tactics, if pursued without thought for cost, can get to places which no strategist would dream of.

  Chapter Fourteen. COUSINS UNDER THE SKIN

  Nineteen hundred and six was a successful year for the Bronx Zoo. A new exhibit was pulling in the crowds. An African Pygmy — Ota Benga by name — was in the same cage as an orang-utan. The exhibit caused an uproar, not because it was a shameful spectacle, but because it promoted the idea of evolution, that apes and humans were related. After a time, Ota Benga was released, in part as a result of his habit of shooting arrows at those who mocked him. He moved to Virginia, where he committed suicide a few years later.

  The Bronx Zoo view of human evolution was once widespread. Linnaeus himself, who first classified animals and plants, put the idea well in 1754: 'All living things, plants, animals and even mankind themselves, form one chain of universal being from the beginning to the end of the world.' Many still see evolution as a smooth progress, a seamless transition from the primaeval slime to New Labour. Linnaeus recognised several distinct varieties among our own species. As well as the yellow, melancholic and flexible asiaticus there was europaeus, white, ruddy and muscular; americanus red, choleric and erect; and afer, black, phlegmatic and indolent.

  The groups of humanity were at different stages. Africans were at the bottom, close to the apes, Asians somewhere in between, and white Europeans — needless to say — at the top. Victorian writers did not hesitate to make the idea clear. Robert Chambers, who wrote an influential book on evolution fifteen years before Darwin, claimed that 'Our brain passes through the characters in which it appears in the Negro, Malay, American and Mongolian nations, and finally is Caucasian. The leading characters, in short, of the various races of mankind, are simply representatives of particular stages in the development of the highest or Caucasian type. The Mongolian is an arrested infant, newly born.'

  The theory that races are different has a long and ignoble history that has brought misery and death in its wake. It reached into medicine. Most people have seen children with Down's Syndrome, which is due to an error in their chromosomes. This was called by its discoverer, Langdon Down, 'Mongolism1 in his 1H66 paper 'Observation on an Ethnic Classification of Idiots' for what seemed to him a good scientific reason — these children had slipped a couple of rungs down the evolutionary ladder to resemble a lower form of life, the Mongols. A Japanese friend once told me that in his country the sa
me condition is called Englishism. The idea is ridiculous. Down's Syndrome is due to a mistake in the transmission of a particular chromosome which is found in all groups of humankind and even in chimpanzees.

  The history of race illustrates, more than anything else, the limitations of biology. Biologists have been talking — or shouting — about race for years. Ignorance and confidence have gone together. Politicians take scientists less seriously than scientists do, but the story of scientific racism, as it was known, is a grim one.

  I have always felt a certain compassion for those whose ability to despise their fellow men is limited by the colour of their victim's skin. Genetics has — and should have — nothing to do with judgements about the value of one's fellow beings. In this sense, the biology of race has no relevance to racism, which is always happy to bend any scientific fact to its perverse ends. The genes do show that there are no separate groups within humanity. This may be reassuring, but should be beside the point. To depend on DNA to define morals is dangerous. Science evolves. It learns more, and theories alter. Our views on human biology have changed and may change again. The same should not be true of attitudes to human rights. Where biology stops and principles begin must not be forgotten.

  Humankind can be divided into groups in many ways; by culture, by language and by race — which usually means by skin colour. Each division depends to some extent on prejudice and, because they do not overlap, can lead to confusion. In 1987, a secretary from Virginia sued her employer for discrimination as she was black. She lost the case on the grounds that, as she had red hair, she must be white. She then worked for a black employer and, undaunted by her earlier experience, sued him for picking on her as she was white. She lost again as the court found that she could not be white as she had been to a black school.

  Nations, too, differ in how they define their racial affinity. In South Africa just one African ancestor, even in the distant past, once meant ejection from the white race. In Haiti, in contrast. Papa Doc proclaimed his country to be a white one, as almost everyone — dark though their skin might be — had a European ancestor somewhere. Other countries developed fine distinctions based on colour. Latin America once recognised more than twenty races. The offspring of a Spaniard and an Indian was a mestizo, that of a mestizo and a Spaniard a castizo, a Spaniard and a negro a mulatto, a mulatto and a Spaniard a morisco, a morisco and a Spaniard an albino, an albino and a Spaniard a torna atras and so on in a lengthy, hair-splitting and subjective series. Races were supposed to be distinct because they descend from different ancestors. Ham, Shem and Japhet, the sons of Noah, were popular candidates. Anthropology began with the- search for perfect examples of each lineage, for racial types. Africans, Europeans and Asians were seen as separate versions of humankind. Perhaps, its students thought, every race was once a pure and unpolluted line, secure in its ancestral homeland. Only in modern times was that purity sullied by interbreeding. Race mixture was against nature (exceptions were allowed in emergency, as when Saints Cosima and Damian, with divine help, transplanted a black leg onto a white patient).

  If the peoples of today are a confused mix of what was once a series of pure races, it might still be possible to identify perfect specimens of the original groups. That unproven idea led human biology round in circles for centuries in a futile attempt to find divisions into which people could be classified. Its early days were spent in a useless search for homelands and migration routes. Harvard University was at the centre of the search for the archetype. Two suitably discreet nude statues once stood in the Pea-body Museum of Anthropology. They were based on measurements made in the 1930s on dozens of male and female students. Average these out, the argument went, and one would produce an image of the ideal Harvard undergraduate — the highest form of human being. A remnant of this philosophy survives in the Miss World Contest whose judges try, and fail, to find an objective definition of the perfect woman.

  Racial types were usually identified from skulls. The word 'Caucasian' reflects a claim that the skull which best represented white-skinned people came from the Caucasus Mountains so that — perhaps — the white race had spread from those remote fastnesses. Years were wasted in measuring skulls rather than thinking about what might make them different. The most popular yardstick was the cephalic index, the ratio of the length and breadth of the head. Tens of thousands of crania from different parts of the world were measured in an attempt to sort out their ancestral stocks.

  The work was futile. There is no evidence at all that there are, or ever have been, populations whose members all share the same cephalic index. Even worse tor the poor craniometers, the skull shape of the children of immigrants to America shifted away from that of their parents towards that of people already there. Its shape is in any case affected by natural selection. Populations from hot places as far apart as Africa and Malaya have similar skull form, which differs from that of Scandinavians or Eskimos. Even if they have different ancestry, they have converged to about the same shape. Natural selection means that shared heads do not prove common homelands.

  So obvious seemed the differences between groups that scientists were blinded to their own results. Samuel George Morton in his Crania Americana of 1830 measured hundreds of skulls. The differences were, he thought, clear: Caucasians had larger brain cases than Mongolians and Malays, who in their turn were better endowed than Africans and Europeans. When the same specimens were re-measured with modern instruments the differences disappeared. Morton's results were due to the omission of some groups which did not fit his ideas, confusion of males and females, and a failure to correct skull size for differences in body size.

  Even so, early workers had enormous confidence in the value of skull shape. Such measurements were used by the Nazis in an attempt to sort out those with Jewish ancestry. The Frenchman Georges Vacher de Lapouge who wrote in 1887 lI am convinced that in the next century millions will cut each others* throats because of one or two degrees more or less of cephalic index' was more correct than he feared.

  Races could also be classified by language. The term 'Aryan', which gained such sinister overtones, came from the idea of a talented people, the Arya, who migrated from a homeland somewhere in the east, bringing their inheritance and their language with them. The French writer Joseph Gobineau, the father of modern racist ideology, in his 1854 'Essay on the Inequality of Human Races' wrote that 'Everything great, fruitful and noble in the work of man on this earth springs from the great Aryan family'. He persuaded himself that the Aryans had spread to found the cultures of ancient Egypt, Rome, China and even Peru and that 'all civilisations derive from the white race'.

  Thor Heyerdahl's famous voyage across the Pacific in search of the founders of the civilisations of Polynesia can be traced back to Gobineau. They gave rise to a long series of attempts to trace historical links among cultures (such as those of the Celts and the Incas) which share sun-worship, massive stone monuments, and mummies. All were supposed to descend from the Aryans, who were often equated with the ancient Egyptians.

  Anthropology is the study of the movement of peoples, genes and cultures. These were once all assumed to be the same thing. To observe one's fellow citizens makes it obvious even to an anthropologist that everyone does not belong to a single racial type: people look different. Difference usually means classification and from there it is a riny step to judgement. The early evolutionists did not hesitate. Blumenbach, who coined the term 'Caucasian', was glad to show where his sympathies lay. Part of his definition was '. the most beautiful race of men.. Nature has lavished upon the women beauties which are not to be seen elsewhere. I consider it impossible to look at them without loving them.. ' Even Rousseau never suggested that the noble savage was black.

  Ninety per cent of the names given to themselves by tribal peoples mean 'men', 'the only men', or 'the best men'; that is, we are human, others less so. The Sioux Indians of North America seem to he an exception. The literal translation of 'Sioux'1 is snake, or enemy. In fact, this
name was given to them by an adjacent tribe (and picked up by the first French settlers). The Sioux themselves call their tribe the 'Lakota' — the humans.

  The idea that humanity was divided into distinct lineages of different quality had a disastrous impact. The tie of the philosophy and policies of the Nazis to anthropology, and the desire to return to a lost time of pure races, is clear. The Gesellschaft fur Rassenhygien (Society for Race Hygiene) was founded in 1905. By 1908 all mixed marriages in German South-West Africa (now Namibia) were annulled and those involved in them deprived of their citizenship. Haeckel himself, the champion of The Origin of Species., wrote that 'The morphological differences between two generally recognised species — for example between sheep and goats — are much less important than those between a Hottentot and a man of the Teutonic race.1 His philosophy ended in disaster.