What do we pass on from generation to generation? A clearsighted guide to heredity
Genealogy is apparently the second most searched subject on the internet. Now that we can map our genes, we want to know where we come from. But heredity is not as simple as the passing on of traits from parents to offspring: mothers can acquire cells from their own children; race “is not a feature of the natural world beyond our social experience”; we can chop up DNA to replace the bits we don’t like.
In this painstakingly researched book, Carl Zimmer takes a long view of heredity. Stories of how discoveries were made often start with farming and plants (Mendel’s peas) and continue via unusual humans (the Habsburg jaw) before being proved or disproved by DNA sequencing, and then potentially rethought. Mini-biographies paint powerful pictures. Emma Wolverton, born in 1889, was sent away by her impoverished family to the Vineland training school for “feebleminded children”. Henry Goddard, who ran the institution, traced her family tree and found evidence, he thought, that the mental deficiency was hereditary. His popular book The Kallikak Family inspired a young man called Adolf Hitler. The Nazis’ eugenics programme was based on research that turned out to be completely false.
In 1910, intelligence tests on immigrants arriving in New York were used to “prove” that “we are getting now the poorest of each race”. One psychologist “claimed blacks were as intelligent on average as a white person after a lobotomy”. It makes you wonder about some of today’s scientists who insist on large innate biological differences between men and women’s minds.
Some of the science around genetic diseases is a little hard to follow, and readers may find the story of Zimmer’s own genome to be too much like navel gazing – especially when he reveals that geneticists found “fifty-three species of bacteria” in that exact spot. But the book offers clear insights into a fastmoving area, and asks big questions. Scientists can eradicate diseases, alter DNA and change human heredity. Should they? What if they get it wrong? by Carl Zimmer, Picador, £25
To buy She Has Her Mother’s Laugh for £22 go to guardianbookshop.com.
She Has Her Mother’s Laugh: The Powers, Perversions and Potential of Heredity