Darwin’s Sacred Cause: How a Hatred of Slavery Shaped Darwin’s Views of Human Evolution
by Adrian Desmond and James Moore
(Houghton Mifflin, 485 pages, $30)

It wasn’t purely a devotion to science that caused Charles Darwin to turn the world upside down, say authors Adrian Desmond and James Moore. The father of evolutionary theory was an abolitionist at heart: If he hadn’t embarked on his journey to the Galápagos Islands already troubled by contemporary rationalizations for slavery, he might never have concluded from the evidence he gathered there that all life shared a common ancestry. Darwin came from an English family steeped in the abolition fight. “It makes one’s blood boil,” he wrote five years before publishing The Origin of Species, to think of the subjugation of so many. When he proposed that various Galápagos finches descended from a shared ancestor, he was arguing knowingly for the common brotherhood of man.

This is “astonishing” news, said Rowan Hooper in New Scientist. A full 150 years after the appearance of Darwin’s earthshaking book, you wouldn’t think that fresh insights into the man and his work were still possible. But Desmond and Moore’s surprising book “spectacularly humanizes” Darwin. For the first time, we see that his around-the-world journey on the Beagle was as much an education in the cruelties of the slave trade as it was a chance to collect biological specimens. He later claimed to be forever haunted by a scream, heard in the Brazilian swamplands, that he believed came from a slave being tortured. Once you start looking for Darwin’s remarks about humanity’s common heritage, said Gregory M. Lamb in The Christian Science Monitor, they seem to “permeate his work.”

Desmond and Moore never quite prove that these beliefs were Darwin’s strongest motivation, said Harper Barnes in the St. Louis Post-Dispatch. But theirs is “a fascinating book, whether you buy its central thesis or not.” Desmond and Moore previously published a highly regarded biography of the win, and the case they make here is “rich and intricate,” said Christopher Benfey in The New York Times. Finishing this book, you can’t help but wonder if this patron saint of empiricism would have “fudged” his evidence had it confounded his expectations. At the very least, he was “amazingly lucky that his benevolent preconceptions turned out to fit the facts.”