The Gene: An Intimate History - Siddhartha Mukherjee Page 0,30

would mimic the mechanism of natural selection. If nature could achieve such remarkable effects on animal populations through survival and selection, Galton imagined accelerating the process of refining humans via human intervention. The selective breeding of the strongest, smartest, “fittest” humans—unnatural selection—Galton imagined, could achieve over just a few decades what nature had been attempting for eons.

Galton needed a word for this strategy. “We greatly want a brief word to express the science of improving stock,” he wrote, “to give the more suitable races or strains of blood a better chance of prevailing speedily over the less suitable.” For Galton, the word eugenics was an opportune fit—“at least a neater word . . . than viriculture, which I once ventured to use.” It combined the Greek prefix eu—“good”—with genesis: “good in stock, hereditarily endowed with noble qualities.” Galton—who never blanched from the recognition of his own genius—was deeply satisfied with his coinage: “Believing, as I do, that human eugenics will become recognised before long as a study of the highest practical importance, it seems to me that no time ought to be lost in . . . compiling personal and family histories.”

Galton was born in the winter of 1822—the same year as Gregor Mendel—and thirteen years after his cousin Charles Darwin. Slung between the two giants of modern biology, he was inevitably haunted by an acute sense of scientific inadequacy. For Galton, the inadequacy may have felt particularly galling because he too had been meant to become a giant. His father was a wealthy banker in Birmingham; his mother was the daughter of Erasmus Darwin, the polymath poet and doctor, who was also Charles Darwin’s grandfather. A child prodigy, Galton learned to read at two, was fluent in Greek and Latin by five, and solved quadratic equations by eight. Like Darwin, he collected beetles, but he lacked his cousin’s plodding, taxonomic mind and soon gave up his collection for more ambitious pursuits. He tried studying medicine, but then switched to mathematics at Cambridge. In 1843, he attempted an honors exam in mathematics, but suffered a nervous breakdown and returned home to recuperate.

In the summer of 1844, while Charles Darwin was writing his first essay on evolution, Galton left England to travel to Egypt and Sudan—the first of many trips he would take to Africa. But while Darwin’s encounters with the “natives” of South America in the 1830s had strengthened his belief in the common ancestry of humans, Galton only saw difference: “I saw enough of savage races to give me material to think about all the rest of my life.”

In 1859, Galton read Darwin’s Origin of Species. Rather, he “devoured” the book: it struck him like a jolt of electricity, both paralyzing and galvanizing him. He simmered with envy, pride, and admiration. He had been “initiated into an entirely new province of knowledge,” he wrote glowingly to Darwin.

The “province of knowledge” that Galton felt particularly inclined to explore was heredity. Like Fleeming Jenkin, Galton quickly realized that his cousin had got the principle right, but not the mechanism: the nature of inheritance was crucial to the understanding of Darwin’s theory. Heredity was the yin to evolution’s yang. The two theories had to be congenitally linked—each bolstering and completing the other. If “cousin Darwin” had solved half the puzzle, then “cousin Galton” was destined to crack the other.

In the mid-1860s, Galton began to study heredity. Darwin’s “gemmule” theory—that hereditary instructions were thrown adrift by all cells and then floated in the blood, like a million messages in bottles—suggested that blood transfusions might transmit gemmules and thereby alter heredity. Galton tried transfusing rabbits with the blood of other rabbits to transmit the gemmules. He even tried working with plants—peas, of all things—to understand the basis of hereditary instructions. But he was an abysmal experimentalist; he lacked Mendel’s instinctive touch. The rabbits died of shock, and the vines withered in his garden. Frustrated, Galton switched to the study of humans. Model organisms had failed to reveal the mechanism of heredity. The measurement of variance and heredity in humans, Galton reasoned, should unlock the secret. The decision bore the hallmarks of his overarching ambition: a top-down approach, beginning with the most complex and variant traits conceivable—intelligence, temperament, physical prowess, height. It was a decision that would launch him into a full-fledged battle with the science of genetics.

Galton was not the first to attempt to model human heredity by measuring variation in humans. In the 1830s and 1840s, the Belgian scientist Adolphe Quetelet—an astronomer-turned-biologist—had begun