thrives on uncertainty. In the 1860s, uncertainty over the source of the Nile was the source of a bitter dispute between two English explorers, John Hanning Speke and Richard Burton. Only two men who have shared a camp for many months could disagree so violently. Speke favoured Lake Victoria, which he had discovered while Burton lay ill in a tent at Tabora; Burton insisted that the source lay in or near Lake Tanganyika. The feud only ended in 1864 when Speke shot himself (perhaps accidentally) on the day he was to debate with Burton in public. Speke, by the way, was right.
Watching this dispute from an influential position in the Royal Geographical Society, and occasionally fanning the flames on behalf of Burton, was a distinguished geographer by the name of Francis Galton. It was Galton’s fate to ignite an even bigger feud in that same year, one that would run for more than a century: nature versus nurture. The nature-nurture debate is a bit like the argument over the source of the Nile. Both thrived on ignorance; the more that came to be known, the less the argument seemed to matter. Both seemed unnecessarily petty. Surely, what mattered more than which lake was the source of the Nile was that Africa contained two vast lakes new to Western science. Likewise, it surely matters less whether human nature is more innate or more learned, but instead the precise way in which it is both. The Nile is the sum of thousands of streams, no one of which can be truly called its source; the same is true of human nature.
Galton’s passion was quantifying. In a long career, he invented, coined or discovered a wide range of things: northern Namibia, anticyclone weather systems, the study of twins, questionnaires, fingerprints, composite photographs, statistical regression and eugenics. But perhaps his most lasting legacy is to have inaugurated the nature-nurture debate and coined the very phrase. Born in 1822, he was a grandson of the great scientist, poet and inventor, Erasmus Darwin, by his second wife. He found his half-cousin Charles’s theory of natural selection both convincing and inspiring, ascribing this immodestly to ‘an hereditary bent of mind that both its illustrious author and myself have inherited from our common grandfather, Dr Erasmus Darwin’. Thus emboldened by his own pedigree, he now found his true calling in the statistics of heredity. In 1865, deserting geography, he published an article on ‘hereditary talent and character’ in Macmillan’s Magazine, in which he revealed that distinguished men had distinguished relatives. He expanded it into a book called Hereditary Genius in 1869.
Galton was simply asserting that talent runs in families. Exhaustively and enthusiastically, he described the pedigrees of famous judges, statesmen, peers, commanders, scientists, poets, musicians, painters, divines, oarsmen and wrestlers. ‘The arguments by which I endeavour to prove that genius is hereditary, consist in showing how large is the number of instances in which men who are more or less illustrious have eminent kinsfolk.’2 It was not very sophisticated reasoning. After all, one might just as well argue the opposite, that the rise of humble men to great eminence would reveal their innate talents triumphing over the disadvantages of circumstance; the clustering of talent in families might indicate shared teaching. Most reviewers thought Galton had overstated the role of heredity and ignored the contribution of upbringing and family. In 1872 a Swiss botanist, Alphonse de Candolle, asserted as much at book length. Candolle pointed out that great scientists in the previous two centuries had come from countries or cities with religious tolerance, widespread trade links, a moderate climate and democratic governments – suggesting that achievement owed more to circumstance and opportunity than to native genius.3
Candolle’s attack stung Galton into a second book, English Men of Science: Their Nature and Nurture, in 1874, in which he employed a questionnaire for the first time, and repeated his conclusion that scientific geniuses were born, not made. It was in this book that he coined the famous alliteration:
The phrase ‘nature and nurture’ is a convenient jingle of words, for it separates under two distinct heads the innumerable elements of which personality is composed.4
He may have borrowed the phrase from Shakespeare, who in The Tempest has Prospero insult Caliban thus:
A devil, a born devil, on whose nature nurture can never stick.5
Shakespeare was not the first to juxtapose the two words. Three decades before The Tempest was first performed, an Elizabethan schoolmaster by the name of Richard Mulcaster, the first headmaster of the Merchant Taylors’ school, was so fond of the antiphony of nature and nurture that he used it four times in his 1581 book Positions Concerning the Training Up of Children:
…[Parents] will have their children nursed as well as they can, without question where, or quarrelling by whom: so as they may have that well brought up by nurture, which they love so well, bequeathed them by nature…God hath provided that strength in nature, wherby he entendes no exception in nurture, for that which is in nature…Which naturall abilities, if they be not perceived, by whom they should: do condemne all such, either of ignoraunce, if they could not judge, or of negligence, if they would not seeke, what were in children, by nature emplanted, for nurture to enlarge…Which being thus, as both the truth tells the ignorant, and reading shewes the learned, we do wel then perceave by naturall men, and Philosophicall reasons, that young maidens deserve the traine: bycause they have that treasure, which belongeth unto it, bestowed on them by nature, to be bettered in them by nurture.6
He repeated the phrase in his next book Elementaries in 1582: ‘whereto nature makes him toward, but that nurture sets him forward’. Mulcaster was a curious character. Born in Carlisle, he was a distinguished scholar and famous, if strict, educational reformer. He quarrelled irascibly with the school governors and was a passionate advocate of the game of football: ‘The foteball strengtheneth and brawneth the whole body,’ he observed. Mulcaster also dabbled in drama, writing several pageants for the royal court, and educating the playwrights Thomas Kyd and Thomas Lodge at his school. He is supposed by some to have been the model for the character of Holofernes, the vain schoolmaster in Love’s Labours Lost, so there is a good chance that Shakespeare either knew Mulcaster or read him.
Shakespeare may also have been the inspiration for the next of Galton’s ideas. Two of Shakespeare’s plays turn on the confusion of twins: The Comedy of Errors and Twelfth Night. Shakespeare was himself the father of twins, and he used mistaken twins to make fiendishly ingenious plots. But, as Galton pointed out, in A Midsummer Night’s Dream Shakespeare introduced a pair of ‘virtual twins’ – unrelated individuals who had been reared together. Hermia and Helena, despite being ‘like to a double cherry, seeming parted, but yet an union in partition’,7 not only look physically unlike each other, but are attracted to different men and end up quarrelling violently.
Galton followed up the hint. The next year he wrote an article entitled ‘The history of twins, as a criterion of the relative powers of nature and nurture’. At last he had a respectable way to test the heredity hypothesis, free of the objections raised against his pedigrees. Remarkably, he deduced that there were two sorts of twin: identical twins, born from ‘two germinal spots in the same ovum’, and non-identical twins ‘each from a separate ovum’. This is not bad. For ‘germinal spot’ read nucleus and you are close to the truth. Yet in both kinds, the twins shared nurture. So if identical twins resembled each other in behaviour more than fraternal twins, then the influence of heredity was supported.
Galton wrote to 35 pairs of identical twins and 23 pairs of non-identical twins, collecting anecdotes of their similarity and difference. Triumphantly he recounted the results. Twins that resembled each other from birth remained similar throughout their lives, not only in appearance but also in ailments, personality and interests. One
