Excerpt from Banquet at Delmonico's by Barry Werth, plus links to reviews, author biography & more

Darwin had long avoided publishing his ideas on human evolution, letting Huxley and others speculate before him on the effects of natural selection and the universal linkages between people and animals. But by 1867, eight years after Origin and following two years of crushing illness - vomiting, nausea, eczema, and an "accursed stomach" that for months on end left him sleepless and all but unable to work - he decided he could wait no longer. His "man-essay," as he had described it to Gray, had grown into two parts. The first, due to be published at the end of the month, addressed the conjoined questions of whether man, like any other species, descended from earlier forms; the manner of human development; and, most explosively, for this had been his urgent agenda since he first recorded his thoughts on evolution in secret notebooks thirty-five years earlier, "the value of the differences between the so-called races of man" - the race question. A follow-up book - a rare sudden respite from his health problems was now letting him surge ahead, writing four hundred pages in three months, and adding, for the first time, photographs - would address the similarities in feelings and expression between humans and animals. Hence his interest in Laura Bridgman.

Darwin informed Gray that he had finished work on the first volume - The Descent of Man, and Selection in Relation to Sex, now at the printer’s - and would soon send him a copy. "Parts, as to the moral sense, will I daresay aggravate you," he wrote, "and if I hear from you I shall probably receive a few stabs from your polished stiletto of a pen."

Polite jests aside, Darwin and Gray had long since argued themselves into a stalemate on many fronts. Darwin had confessed to Gray a year earlier that he was having great difficulty explaining the animal underpinnings of civilized behavior - the "moral sense" - and he dreaded another onslaught of scalding criticism, public and private, from Gray and others. Many people might be prepared for Darwin to claim that man physically descended from apes, as Huxley and several other widely respected naturalists had already done, through the process of natural selection - "survival of the fittest," to use Spencer’s phrase. But how did one explain a mechanism for discerning right from wrong? Good from evil? Righteousness from sin? What animal ancestry, he knew he’d be asked, could possibly account for such virtues as a love of justice, or of Jesus?

All these added up to the "highest and most interesting problem for the naturalist," which Darwin now sought to answer. He had come to attribute morality to a combination of three evolutionary forces: instinctive sympathy born (as in many other species, notably dogs and monkeys) of family and tribal ties in the struggle for survival; habit ingrained by social behavior; and education. At the same time, natural science contained for Darwin, who grew up in a world of deep-seated antiroyalist and anti- Anglican leanings, a political thrust. Nothing so appalled him as blind Christian acceptance of the immorality and sufferings of genocide and slavery - nothing except the use of science to justify that indifference. Loath to offend a pious wife and friends like Gray, he withheld from making direct attacks on religion in his new work, seeking instead to show only how such creeds might have evolved. "How so many absurd rules of conduct, as well as so many absurd religious beliefs, have originated, we do not know," he wrote in Descent,

but it is worthy of remark that a belief constantly inculcated during the early years of life, whilst the brain is impressible, appears to acquire almost the nature of an instinct; and the very nature of an

Darwin had made up his mind about racial origins during his voyage, where he first encountered the "shocking barbarity" of slavery in Brazil, then primitive "savages" in Tierra del Fuego, but only now felt confident enough in his research to publish his theory. Two views of racial descent recently competed in Western thought, neither egalitarian. People either believed all humans descended from a single stock (monogenism), and that while the entire species had degraded since Creation, some races, usually those in hot climates, degraded more than others; or else that the races were created separately and hierarchically, with distinct and unequal endowments (polygenism). Either way, whites had no difficulty deeming themselves intellectually and morally superior. Darwin, though he shared in the general self-congratulation, held the radical notion that racial distinctions were fundamentally cosmetic: that features such as skin color and hair texture were simply caused by sexual selection - different beauty standards and mating preferences among different groups. However disturbing the notion to contemporary Western sensibilities, he believed that all mankind was one species. As he now predicted confidently in Descent, "when the principles of evolution are generally accepted, as they surely will be before long, the dispute between the monogenists and the polygenists will die a silent and unobserved death."

Excerpted from Banquet at Delmonico's by Barry Werth. Copyright © 2009 by Barry Werth. Excerpted by permission of Random House, a division of Random House, Inc. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.