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Darwin the Liberator

How evolutionary thought undermined the rationale for slavery.

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Reviewed by Thomas Hayden
Sunday, February 15, 2009; Page BW03


How a Hatred of Slavery Shaped Darwin's Views on Human Evolution

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By Adrian Desmond and James Moore | Houghton Mifflin Harcourt. 485 pp. $30


By Jerry A. Coyne | Viking. 282 pp. $27.95

Charles Darwin and Abraham Lincoln have been spotted together a lot recently -- in a book by the New Yorker's Adam Gopnik, in a George Will column, even on the cover of Newsweek -- because they happen to have been born on the same day 200 years ago: Feb. 12, 1809. After noting that coincidence, however, commentators often miss the most direct connection between the bicentennial birthday boys: Each, in his own way, fought vigorously against slavery.

Contrary to myth, Lincoln was late to adopt the cause of emancipation. His goal at the outset of the Civil War was to save the Union, not to free the slaves. Darwin, though born into a family of dedicated British abolitionists, was similarly slow to rise in opposition to the worldwide trade. He did not become passionate about it until he saw slavery up close in South America during his expedition aboard the Beagle in the 1830s. But his contribution to the cause, though more philosophical and less immediate than Lincoln's, was no less profound.

In Darwin's Sacred Cause, Adrian Desmond and James Moore contend that abhorrence of slavery inspired and shaped Darwin's theory of evolution. To grasp his grand project, we have first to understand one of the great scientific battles of the mid-19th century. "Polygenists," such as the American physician Samuel George Morton, held that the human races were each a distinct species, and each the result of a separate act of creation. They considered Anglo-Saxon whites superior in every way to the "debased" and "savage" darker races, which were relegated to a supposed natural position of servitude. Darwin, a man of his time, also believed in the superiority of whites. But he was convinced that all humans were one species, and that those not born to English manners could be improved through education. With growing horror, he observed slavery in Brazil and the genocide of indigenous peoples in Argentina, and decried both in his Voyage of the Beagle: "It makes one's blood boil, yet heart tremble, to think that we Englishmen and our American descendants, with their boastful cry of liberty, have been and are so guilty," he wrote in the 1845 edition of his popular travelogue.

Fourteen years later, when he published On the Origin of Species, Darwin described the evolution of plants and animals but not of humans. This famous omission has been variously ascribed to an abundance of caution, concern for his wife Emma's religious sensibilities or even a preference for bugs and finches over his own species. But Desmond and Moore make the case that human evolution was at the forefront of Darwin's thinking. By proving that all animal species descend from common ancestors, Darwin hoped to undercut the biological rationale for slavery without the need to draw distracting fire by addressing human origins directly, especially before he had amassed all the data he would need to prove decisively that humans also evolved.

"Human evolution wasn't his last piece in the evolution jigsaw; it was the first," Desmond and Moore write. "From the very outset Darwin concerned himself with the unity of humankind. This notion of 'brotherhood' grounded his evolutionary enterprise."

In lesser hands, this recasting of Darwin's life as an extended anti-slavery campaign could seem like a stretch, perhaps to justify a book for the Darwin-Lincoln double anniversary. But Desmond and Moore, professional historians of science who are widely regarded as Darwin's finest biographers, barely mention Lincoln (though they do show Darwin reading the news of America's Civil War with great interest). More to the point, the authors follow Darwin's example by deciding that the best way to prove a controversial point is "to pile on crippling quantities of detail." Drawing on his manuscripts, notebooks, letters and even marginal jottings in books, they construct a theory of both broad scope and meticulous documentation, leaving critics with few holes to probe.

A small example: Polygenists maintained that mixed-race children would be sterile, much like mules. Darwin queried his contacts around the world to collect first-hand reports to disprove the point. Desmond and Moore also found that he marked up a copy of Intermarriage, an 1838 book on miscegenation, and made a fragmentary note to himself "on advantages of crossed races of Man." What emerges from hundreds of such finds, as from Darwin's own theory, is a suddenly clarifying new view of a familiar picture. Darwin's intellectual "starting point," according to this book, was not the exotic wildlife he observed on the Galapagos Islands. It was "his hatred of the slavers' desire" to make "the black man . . . sub-human, a beast to be chained." By observing Darwin's life and work anew, Desmond and Moore give us "the reverse of the fundamentalists' parody" of him as anti-God, inhuman and immoral. They describe a humanitarian who was "more sympathetic than creationists find acceptable, more morally committed than scientists would allow."

And therein lies a paradox. Two centuries after his birth and 150 years after the publication of On the Origin of Species, Darwin's memory is kept alive as much by his status as a lightning rod in the culture wars as by his scientific legacy. He ranks among the most famous scientists of all time, but how much do most of us really know about his work and the research it has inspired?

For those who want to understand the evidence for evolution, Jerry A. Coyne's Why Evolution Is True is a fine place to start. As his unsubtle title suggests, Coyne's purpose is to banish the arguments of creationists and their intelligent design fellow travelers. Much as Darwin did, he draws upon geology and the fossil record; biogeography, or the distribution of plants and animals; and the similarities and differences among living species. But gaps that once frustrated Darwin, such as so-called "missing links" in the fossil record, can now be filled. Coyne cites the 2004 discovery of Tiktaalik, a 375 million-year-old shallow-water creature caught in mid-transition from fish to amphibian, with delicate aquatic bones thickening into an air-breather's sturdier frame. "There is no reason why a celestial designer, fashioning organisms from scratch like an architect designs buildings, should make new species by remodeling the features of existing ones," Coyne writes. "But natural selection can act only by changing what already exists."

Coyne also has the advantage of 150 years of scientific progress in genetics and molecular biology, much of which would have amazed Darwin. He misses the opportunity to explore the latest insights from genome science, which is allowing scientists to observe the process of evolution at the level of individual DNA changes. But he builds a strong case for the fact of evolution, and for Darwin's theory of how it works. (That species change over time isn't theoretical; how and why the changes occur is the subject of "evolutionary theory.") Coyne addresses many of the common creationist arguments head-on, outlining how complex systems such as eyes and biochemical pathways can evolve by natural selection. To his credit, however, the author acknowledges his strategy's fatal flaw: The refusal to accept evolution has precious little to do with reason, logic or evidence. Like the introductory college courses it too-closely resembles, Why Evolution Is True is packed with facts and clear explanations but is unlikely to change many minds.

If Darwin's intent was to prove the biological connectedness of all humanity, then he succeeded brilliantly; he demolished the scientific justification for slavery prevalent in his time. Yet, ironically, more than a few bigots and crackpots have tried to use his ideas to justify further racism, starting soon after the publication of On the Origin of Species with the vogue for "social" Darwinism. Darwin detested those attempts, which were so at odds with what Desmond and Moore call his "sacred cause."

Two hundred years after his birth, Darwin has been vilified by some, sanctified by others and, perhaps, misunderstood by most. Rich in detail, remarkably readable and engaging, Desmond and Moore's reassessment may do no more than other books to convince evolution's deniers of the grandeur of Darwin's view of life. But by revealing the motive behind his work, Sacred Cause is the finest birthday tribute to Charles Darwin in many years. ·

Thomas Hayden is co-author of "Sex and War: How Biology Explains Warfare and Terrorism and Offers a Path to a Safer World."

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