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Darwin Correspondence Project

Human nature

The early 1870s were a turning point in the global debate about human evolution, with deep implications for science, colonial expansion, industrial progress, religious belief, and ethical and philosophical debate. Darwin’s correspondence from this period is of fundamental importance for understanding both the development of his theory of human origins and its relationship to prevailing assumptions about human nature.

I believe there exists… an instinct for truth … & that our having such an instinct is reason enough for scientific researches without any practical results ever ensuing from them.
Darwin to J. S. Henslow, [1 April 1848]
I demur to your saying … that animals are governed only by selfish motives. Look at the maternal instincts & still more at the social instincts. How unselfish is a Dog!
Darwin to Neil Arnott, 16 February [1860]
I quite agree how humiliating the slow progress of man is; but everyone has his own pet horror…
Darwin to J. D. Hooker, 9 February [1865]
My object is to make out … the causes of the movement of certain muscles under various emotions in man and the lower animals.
Darwin to James Crichton-Browne, James, 22 May 1869
…you feel astonished at my bringing man & brutes so near together in their whole nature (though with a wide hiatus)…
Darwin to St G. J. Mivart, 21 April [1871]
…the horrid doubt always arises whether the convictions of man’s mind, which has been developed from the mind of the lower animals, are of any value…
Darwin to William Graham, 3 July 1881

DAR 53.1 C125r.jpg

Sulky child from Expression
Sulky child from Expression, pl. 2; DAR 53.1 C125r
By permission of the Syndics of Cambridge University Library


Darwin's interest in emotional expression can be traced as far back as the Beagle voyage. He was fascinated by the different sounds and gestures among the peoples of Tierra del Fuego, and on his return from the voyage he started recording observations in a set of notebooks, later labelled 'Metaphysics on Morals & Speculations on Expression'. Details about the facial and bodily movements accompanying various emotions were entered, alongside remarks on the origins of language, aesthetic taste, and sympathy, comparing the behaviour of humans and animals.

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Caricature by George Montbard
Caricature by George Montbard
DAR 225: 178
Cambridge University Library


There are more than five hundred letters associated with the research and writing of Darwin’s book, Descent of man and selection in relation to sex (Descent). They trace not only the tortuous route to eventual publication, but the development of Darwin’s thinking: his utter confidence that humans had been subject to natural selection, coupled with reluctance to press the point too soon; his early inkling that racial differences were the result of sexual selection; and his increasing conviction that sexual selection explained a range of distinctive male and female characteristics across the animal kingdom – colour, pattern, scent, and song, as well as antlers, horns, and pincers. 

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DAR 186:1 (click to enlarge)

Darwin’s queries on expression

When Darwin resumed systematic research on emotions around 1866, he began to collect observations more widely and composed a list of queries on human expression. A number of handwritten copies were sent out in 1867 (see, for example, letter to Fritz Muller, 22 February [1867]). The list was printed for ease of distribution sometime in late 1867 or early 1868. Darwin went over his questions, refining them, as we can see from this copy of the printed list with small corrections in Darwin’s hand.

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Darwin on human evolution

'I hear that Ladies think it delightful reading, but that it does not do to talk about it, which no doubt promotes the sale.' For the first time online you can now read the full texts of nearly 800 letters Darwin wrote and received during 1871, the year in which his controversial first public statement on human evolution was published.  The extraordinary number of letters reflects the excitement the book – Descent of man and selection in relation to sex – caused. All 2500 copies of the first printing sold immediately, and 5000 more copies were published during the year. 

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Hensleigh Wedgwood

Hensleigh Wedgwood, Emma Darwin’s brother and Charles’s cousin, was a philologist, barrister and original member of the Philological Society, which had been created in 1842. In 1857, while Wedgwood was preparing a dictionary of English etymology, he wrote to Darwin suggesting that the common origin of the French “chef” and the English “head” and “bishop” illustrated the parallels between extinct and transitional forms in language and palaeontology.

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Hokusai Manga, a collection of Japanese drawings, by Hokusai Katsushika
Hokusai Manga, a collection of Japanese drawings, by Hokusai Katsushika
CUL FJ.963.6
Cambridge University Library

The expression of emotions

Darwin’s work on emotional expression, from notes in his Beagle diary and observations of his own children, to questionnaires, and experiments with photographs, was an integral part of his broad research on human evolution. It provided one of the main bodies of evidence for the descent of humans from animals.

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Results of the Darwin Online Emotions Experiment

Thanks to all who took part in our online emotions experiment – over 18,000 of you! The formal stage of the experiment is now over, but it will be staying online as an activity, so if you don’t want to know the results, look away now.  If you’d like to find out more about the experiment, or have a go yourself, click here. We promised to give some feedback and so here is what we made of the results.  We’ve summarised the top 20 responses to each photograph in the pie charts below.

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Emotion Experiment

Between March and November 1868, while Darwin was researching his book The Expression of the Emotions in Man and Animals, he showed a succession of visitors a set of photographs of human faces, some with the muscles artificially contracted by electric probes, and asked them what emotion they thought the photographs conveyed. Darwin’s research has striking parallels with contemporary facial recognition experiments. We have recreated Darwin’s expression experiment online, using 21st century techniques to study many of the same problems that Darwin was interested in, using the same photographs Darwin used more than 100 years ago. Try the emotion experiment for yourself.

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Patagonian Indians, Gregory Bay
Patagonian Indians, Gregory Bay, by Conrad Martens
CUL Add 7983: 31
Cambridge University Library

Race, Civilization, and Progress

Darwin's first reflections on human progress were prompted by his experiences in the slave-owning colony of Brazil, and by his encounters with the Yahgan peoples of Tierra del Fuego. Harsh conditions, privation, poor climate, bondage and servitude, could impede human progress or cause degeneration. In the "Fuegians", Darwin thought he had witnessed man in his most "primitive wildness" (letter to Henslow, 11 April 1833). They represented both the yawning gap between wild and domesticated humans, and the unsettling proximity of the savage and the civilized.

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Moral Nature

In Descent of Man, Darwin argued that human morality had evolved from the social instincts of animals, especially the bonds of sympathy and love. Darwin gathered observations over many decades on animal behavior: the heroic sacrifices of social insects, the tender bonds of affection between female apes and their offspring, the courage and loyalty of dogs for their masters. Cooperation and regard for others were beneficial to animal communities as a whole, and helped them to survive in the battle for life. 

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