Darwin believed that the blood was in some way the agent, the vital fluid of parents mixing in their children. He was also sufficiently impressed by the similarities of parent and offspring to propose his law of "use and disuse"; that characters much utilized in one generation would be inherited by the next, while those not employed woudl slowlly disappear.
Such beliefs are so persuasive that it seems almost unfair that they are wrong. Darwin's failed attempts to reconcile his notions about heredity with his theory of evolution led him into a morass from which he could not excape. The more he thought about the issue, the more he saw the problems that arose if inheritance was indeed based on the experiences of parents and the blood of their children. ... The great truth about the mechanism of inheritance, which is less obvious and more simple than anything [Darwin and his followers] imagined.
The fatal flaw in the idea of blood as the bearer of qualities that mix as one generation succeeds the last was noticed not only by Darwin but by the British government when, in 1971, they set out to redefine the essence, the sanguis, of being British.
Once, British citizenship was an unequivocal thing. It depended only on "birth within the dominions and allegiance" of the Crown. The 1971 Immigration and Nationality Act had an unspoken aim; to keep coloured immigrants out. There was, though, a problem, as a supposedly liberal society could not just discriminate on the basis of race. The authorities did not wish toe exclude all Commonwealth citizens. White South Africans, Kenyans, or Australians would be enraged if they could not return to what many still saw as their homland. What was needed was a way of designing a door to the British Isles that admitted only those who seemed to belong.
The solution was simple, cynical and ingenious. To establish a right to live in Britain, a new rule was made. It was based on a politically expedient model of inheritance. Having a passport was not enough. Instead, the idea of "patriality" was born. This resided in the blood. British blood might be rather special fluid, but it was defined as having a fatal weakness. Once watered down, it lost its power.
The right to enter was made to depend on having the right proportion of the magic substance. Any Citizen of the United Kingdom and Colonies - and there were millions, from Uganda to Hong Kong - could gain patriality, the right of abode in the UK, only by birth in these islands or by haveing a native-born parent or grandparent. True Britishness, rendering its possessor eligible to live in Britain, was defined for the purpose of the act as having at least a quarter, one grandparent's worth, of blood inherited from someone born here. The rules for the citizens of independent Commonwealth countries (such as Canada or Australia) were even stricter. To be patrials they had to have a mother or father whose birthplace was in Britain.
Conveiently enough, most people in the British Isles around the time when the crucial grandparents or parents were born had white skins. In spite of their stiff blue passports, the millions of Africans and Asians who had been told to be proud of their link with the home of democracy found that the document had lost its value. For Canadians and Australians, things were - temporarily - not quite so bad; for a time, the law allowed the children of the many Britons who had emigrated after the War to return. Their grandchildren, though, need not apply.
Now, a generation after it was formulated, most have lost the right of residence. As time passes, the number of children born overseas who have the crucial connection gets smaller. The critical British-born descendants no longer provide the large enough fraction of the child's heritage. As the years go on, fewer and fewer Commonwealth citizens will be able to claim the vital ratio of true British blood, passed down from a privileged parent or grandparent. In time, almost no one born outside these islands will have the automatic right to dwell in them; the blessing has been thinned down until it means nothing.
The blending rule was applied in reverse in the United States. Anyone with a black ancestor, however distant, was defined as black. One drop of black blood was enough to pollute the line forever: the stain could never be lost. The rule originated as a way of enlarging the slave population with the illegitimate children of slaveholders. As recenlty as 1986 the Supreme Court refused to review a ruling that a light-skinned Louisiana woman whose black great-great-great-grandmother was the mistress ofa French planter should be classified as black.
All this is the inevitable result of inheritance based on dilution. Sooner or later, if liquids mix, everyone becomes the same. Genetics is then based on an average, not on differences. Charles Darwin (like the British Government) had thought, when he wrote The Origin of Specis, that inheritance involved the blending of bodily fluids. He too realized that, if it does work in this way, any advantageous character would soon become so thinned out that, like a small quantum of British blood, it would be worthless. Evolution depends on the unfair distributeion of benefit, with success given to those that have over those that have not. Any mechanism that automatically leads to equality will stop it in its tracks. Darwin never sorted out this problem.
Another oddity about inheritance that worried him because it did not fit the idea of the minglingg of bloods was atavism. Now and again, an individual is born who looks not like the average of its parents but like a distant ancestor or relative.
Most horses have but a single hoof on each foot, although they do possess small bones within the legs, the remnants of ancient toes. Both Julius Caesar's war horse and Bucephalus, the steed of Alexander the Great, had, though, toes that worked just as well as those of a dog or cat.
Whatever made them must have been hidden somewhere in the animal's heritagbe to reappear unchanged many generations later. The same happens in humans. A few people are born - just like dogs - with extra nipples; a very few like apes, with a thick coat of hair on face and body.
Thid did not fit at all with the idea of mixing of fluids. How could such characteristics remain distinct through thousandes of generations if they were watered down each time someone lacking the trait mated with someone who had it?
The answer was simple but universally overlooked. ... Mendel showed that inheritance resides not in liquid form in the blood or its semens, but as units of information passed on through sperm and egg. ... Characteristics acquired during an individual's lifetime are not inherited. To be more precise, they are not inherited throught the biological machinery: nobody denies that education, wealth and social position - blue blood, indeed - are passed from generation to generation. ...
Darwin's failure to detach the fate of genes from those who bear them led to the greatest of his confusions, the idea of use and disuse, the inheritance of acquired characters. ... William Paley's book notes that Jewish children are born with foreskins, disproving the claim that traits obtained during life are passed to the next generation. ...
Nowhere has the dispute between nurture and nature been more pointed than in the Soviet Union. Genetics came to a stop there for twenty-five years because of ideology. That some qualities are beyond human intervention because they are coded into biology could not be accepted by Marxists. ... Marx had insisted that man could be changed by altering society; once the revolution had succeeded a new and better humankind would emerge. This was, in itself, a theory about inheritance. The process of producing a new man had gone further in the Soviet Union than anywhere else. The masses had fulfilled the first five-year plan in four years, destroying millions of kulaks and intellectuals - wreckers and saboteurs - in the process. ...
The ideology - and the faked experiments - had disastrous effects. In 1942 Lysenko claimed that if winter wheat (which is cultivated in places with a climate mild enough to sustain it) were planted in Siberia among the stubble of spring what (which grows over the summer) it would be able to survive the coldest winter. The "vernalization of wheat" (which simply did not work) was imposed on farmers and led to famine.
In 1948, genetics in the USSR stopped. ...The inheritance of acquired characters became law. ... Much later Khruschev said to Lysenko: "You and your experiments can go to the moon"' and, by the 1970s, genetics in the Soviet Union had rejoined the world of science.
Lysenko was the mirror of the view that held in Germany and elsewhere during the 1930s: that genes did everything. Hitler himself is known to have read a textbook on human genetics and many experts in "race hygiene" (as the subject was then called) were involved in the extermination movement. Greeding from those with the finest genes and eradicating those with the worst was the only way to improve society. That idea, too, failed the test of history.
