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Separated at Birth: The Interlinked Origins of Darwin’s Unconscious Selection Concept and the Application of Sexual Selection to Race


This essay traces the interlinked origins of two concepts found in Charles Darwin’s writings: “unconscious selection,” and sexual selection as applied to humanity’s anatomical race distinctions. Unconscious selection constituted a significant elaboration of Darwin’s artificial selection analogy. As originally conceived in his theoretical notebooks, that analogy had focused exclusively on what Darwin later would call “methodical selection,” the calculated production of desired changes in domestic breeds. By contrast, unconscious selection produced its results unintentionally and at a much slower pace. Inspiration for this concept likely came from Darwin’s early reading of works on both animal breeding and physical ethnology. Texts in these fields described the slow and unplanned divergence of anatomical types, whether animal or human, under the guidance of contrasting ideals of physical perfection. These readings, it is argued, also led Darwin to his theory of sexual selection as applied to race, a theme he discussed mainly in his book The Descent of Man (1871). There Darwin described how the racial version of sexual selection operated on the same principle as unconscious selection. He thereby effectively reunited these kindred concepts.

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For invaluable aid in securing primary sources for this project I thank the Interlibrary Loan department of the Augustana College Library, Rock Island, Illinois. I am also grateful for useful adivce from Nicholas Gill and from three anonymous readers.

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Correspondence to Stephen G. Alter.

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Alter, S.G. Separated at Birth: The Interlinked Origins of Darwin’s Unconscious Selection Concept and the Application of Sexual Selection to Race. J Hist Biol 40, 231–258 (2007).

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  • artificial selection
  • Charles Darwin
  • race
  • sexual selection
  • unconscious selection