DARWIN, CHARLES. 1809-1882. Autograph Manuscript Leaf Signed ("Ch. Darwin") and explicitly titled "The Descent of Man," being an early draft on the origin of the human species which was eventually published in Descent of Man, 1 p, 167 x 210 mm, 12 lines in two different inks, c.1856-1865, written on the lower half of a folio, separated from the larger leaf along the top edge, old folds, the earlier text with numerous emendations and corrections, with additional corrections and additions in darker ink, c. 1868-1870, old folds.

A HIGHLY IMPORTANT MANUSCRIPT LEAF ON THE THEORY OF EVOLUTION APPLIED TO HUMAN ORIGINS - an exceptional manuscript leaf for The Descent of Man, articulating the central theme, and differing markedly from the published text. An early draft that ultimately evolved into page 228 of the first edition text, this outstanding leaf addresses the question of whether humanity is one or many in species. Likely repurposed from Darwin's manuscript "big book," Natural Selection, which he began in 1856 and continued adding to throughout the 1860s, this draft evinces Darwin wrestling with the critical issue of how to apply the evolutionary framework of speciation to the scientific analysis of humanity and its races.

The culmination of Darwin's theory of evolution, The Descent of Man demonstrates that all human beings are members of a single species. For the first time in print, Darwin scientifically analyzes the human being in evolutionary perspective, a subject he had been pressed on before but had studiously avoided because of the controversy stirred by the topic. Darwin here explicitly introduces a new evolutionary principle – sexual selection – which he uses to explain the variegation among the races of mankind. The final chapter of Descent, "On the Races of Man," of which this leaf forms part, contains Darwin's most important and original contribution to the issue of human evolution, testifying to the unity of the human species and explaining the basis for mankind's variegated races. It has recently been argued, in particular by Desmond and Moore in Darwin's Sacred Cause (University of Chicago Press, 2009), that Darwin was motivated to prove the theory of evolution for the express purpose of demonstrating the common origin of mankind.

Darwin repurposed leaves and portions of leaves from his Natural Selection manuscript throughout his later career, beginning with the first edition of On the Origin of Species in 1859. Indeed, Darwin's original title for the Origin was "An abstract of an Essay on the Origin of Species," which publisher John Murray smartly rejected. Autograph notes found in books from Darwin's library (e.g., Nott and Gliddon's 1855 book Types of Mankind) indicate that Darwin originally intended to discuss human evolution in chapter six of his Natural Selection manuscript, but ultimately abandoned the attempt because of an insufficiency of hard scientific data, and because he had not yet fully developed the evolutionary principle of sexual selection. According to R.C. Stauffer, who edited a scholarly reconstruction of Natural Selection in 1975, "There are now folios missing from the surviving Natural Selection manuscript and other folios with part of the text cut away. These gaps can often be related to topics which were treated in both works and it seems evident that he simply incorporated passages from the older manuscript into the new one by transferring what he had already written to save himself recopying" (Stauffer, Charles Darwin's Natural Selection, Cambridge, 1975).

Unknown to scholarship, and highlighting Darwin's continuing difficulty with the formal definition of the term "species" even at this late juncture in his scientific career, this leaf is a critical resource for our understanding of the historical development of Darwin's argument in the Descent, as well as the general development of his theory of evolution. The present leaf contains both contemporary and later edits to the text, the later edits being made in a darker ink matching that used in Darwin's signature and the titling of the leaf as "Descent of Man." While the original leaf could have been composed from 1856 and later, the earliest written record we locate of the phrase "Descent of Man" is a February 6, 1868 letter to Ernst Haeckel in which Darwin uses the phrase in reference to his newly undertaken work. Significant textual differences between this leaf and the final printed form of the text suggest that these dark-ink edits likely date to 1868.

Darwin manuscript leaves directly addressing human evolution are exceedingly rare, and those both signed and titled by Darwin even moreso. As the surviving manuscript of Natural Selection in fact contains very little directly pertinent to human evolution, and as surviving leaves of The Descent of Man are relatively few in number (significantly rarer than known manuscript leaves from the Origin), the present leaf is one of only a relatively small number of extant Darwin manuscript sources directly treating human evolution. Directly addressing human evolution and the definition of "species," and comprising a key passage from the most important chapter of Descent, the present leaf is one of the finest and most important Darwin autographs in private hands.

REFERENCE: Stauffer, R. C. ed. Charles Darwin's Natural Selection; being the second part of his big species book written from 1856 to 1858. Cambridge: Cambridge University Press, 1975.