Siddhartha Mukherjee’s book is a tourist guide to the twenty-first century’s uncharted continent, the human genome.
My favourite quotation from Charles Darwin: “Ignorance more frequently begets confidence than does knowledge.” In that brief sentence, the founder of modern biology unknowingly summarised in advance the history of genetics, from the eugenical ideas of his half-cousin Francis Galton to Bill Clinton’s statement that the human genome sequence was “the most important, the most wondrous map ever produced by humankind”.
The eugenics movement led to disasters known to everyone. It is not yet dead: Francis Crick once claimed that “no newborn should be declared human until it has passed certain tests regarding its genetic endowment”, and our own government’s decision to deny child support to poor people irresponsible enough to have more than two offspring (the agent of the policy has four) is in the same tradition. As a reminder of our ignorance, the DNA chart looks more like a medieval atlas than a modern map – with geneticists, in unconscious parallel to Swift’s words, the geographers who “in Afric maps/With savage pictures fill their gaps,/And o’er inhabitable downs/Place elephants for want of towns”.
Siddhartha Mukherjee’s book is a tourist guide to the new Africa, the human genome. The chart of that continent does indeed have too many metaphorical elephants and a noticeable shortage of productive towns: there are only about 20,000 working genes in the conventional sense, rather than the millions once assumed to exist (and why do tomatoes have more than we do?). They are surrounded by vast numbers of more or less mysterious molecular beasts, some of them parasites that invaded long ago, others the mouldering corpses of once-noble creatures, and yet more – the so-called junk – known more in its anatomy than in what it actually does. Lengthy as this book is (and Mukherjee might have gained from turning to his own account of the genome’s ability to cut out redundant and repetitive sections), it gives a full and lively account of the development of the subject, from its birth in the 19th century to its infancy in the 20th and its uncertain adolescence in the 21st.