The following extracts and selected letters explore Darwin's views on the operation of sexual selection in humans, and both his public and privately expressed views on its practical implications for female education and women in the workforce.
Published statements: selected extracts
1) “And this leads me to say a few words on what I call Sexual Selection. This depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring….” On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life, (London: John Murray, 1st ed., 1859), p. 88.
2) “There is one other point deserving a fuller notice. It has long been known that in the vertebrate kingdom one sex bears rudiments of various accessory parts, appertaining to the reproductive system, which properly belong to the opposite sex…” The descent of man, and selection in relation to sex, (London: John Murray, 1st ed., 1871), vol. 1., pp. 207 – 208.
4) “Difference in the Mental Powers of the two Sexes… Woman seems to differ from man in mental disposition, chiefly in her greater tenderness and less selfishness…” Read full extract Descent (1871), vol. 2, pp. 326 – 327.
5) “The chief distinction in the intellectual powers of the two sexes is shewn by man attaining to a higher eminence, in whatever he takes up, than woman can attain—whether requiring deep thought, reason, or imagination, or merely the use of the senses and hands….” Descent (1871), vol. 2, pp. 327.
6) “…Thus man has ultimately become superior to woman. It is, indeed, fortunate that the law of the equal transmission of characters to both sexes has commonly prevailed throughout the whole class of mammals; otherwise it is probable that man would have become as superior in mental endowment to woman, as the peacock is in ornamental plumage to the peahen.” Descent (1871), vol. 2, pp. 328 – 329.
7) “In order that woman should reach the same standard as man, she ought, when nearly adult, to be trained to energy and perseverance, and to have her reason and imagination exercised to the highest point; and then she would probably transmit these qualities chiefly to her adult daughters….” Descent (1871), vol. 2, p. 329.
8) “Man is more powerful in body and mind than woman, and in the savage state he keeps her in a far more abject state of bondage than does the male of any other animal; therefore it is not surprising that he should have gained the power of selection…” Descent (1871), vol. 2, pp. 371 – 372.
Letter 1113 - Darwin to Whitby, M. A. T., [2 September 1847]
Darwin questions Mrs. Whitby, whom he had met at a meeting of the British Association, about the difference in the flight capacity of male and female silkworm moths. He also requests the results of experiments she has undertaken to determine the heritability of dark eyebrows.
Darwin writes to his fiancée, Emma, detailing the influence that he hopes her presence will have on his life and character.
Letter 5670f - Darwin to Kingsley, C., [6 November 1867]
Darwin discusses ‘rudiments’ which, he says, provide evidence that all vertebrates evolved from a single hermaphroditic progenitor.
Letter 7123 - Darwin to Darwin, H. E., [March 1870]
Darwin thanks his daughter, Henrietta, for editing a manuscript version of chapter two of Descent on the mental powers of man and lower animals.
Letter 7329 – Murray, J. to Darwin, [28 September 1870]
Written shortly before the publication of Descent, Murray tells Darwin that he believes the book will be a success but will cause a stir among men. He suggests that certain passages might be “toned down” in order to minimise impeding general perusal.
Letter 8146 – Darwin to Treat, M., [5 January 1872]
Darwin praises Mary Treat’s observations. Darwin encourages Treat to publish the results of her entomological experiments and congratulates her on the publication of her work on Drosera.
Letter 10546 – Darwin to Editor of The Times, [23 June 1876]
Darwin forwards to The Times an article from Nature on the necessity of animal experimentation. He hopes that the article will make women in particular think about the benefits of experimentation to the progress of physiology.
Letter 10746 – Darwin to Dicey, E. M., 
Darwin gives his opinion on the education of girls in physiology. He tells Elinor Dicey that he would regret any girl being denied the right to pursue the science. He believes that girls and boys alike should be exposed to the sight of dissection in the course of their training and regrets his personal inability to cope well with the sight of blood.
Letter 11267f – Darwin, S. to Darwin, [3 December 1877]
Darwin’s daughter-in-law thanks Darwin for a welcome note which was left at her new marital home while she and her new husband, William, were on their honeymoon. Sara expresses anxiety about her domestic duties but explains that she will take lessons in housekeeping from Mrs Cutting.
Letter 13607 – Darwin to Kennard, C. A., [9 January 1882]
Darwin responds to Caroline Kennard’s enquiry about statements made about the sexes in Descent. Darwin reasserts his belief that women are men’s moral superiors and intellectual inferiors but acknowledges the cultural, as opposed to biological, nature of sex differences.