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Darwin Correspondence Project

Animals, ethics, and the progress of science

Dog caressing its master.jpg

Dog caressing its master
Dog caressing its master
Expression, p. 55

Darwin’s view on the kinship between humans and animals had important ethical implications. In Descent, he argued that some animals exhibited moral behaviour and had evolved mental powers analogous to conscience. He gave examples of cooperation, even compassion, across the species divide, including the affection and devotion of domestic animals for their human ‘masters’. He added that sympathy for ‘all sentient beings’ was perhaps the highest virtue yet attained by ‘man’ (see Descent, pp. 75-7, 101). In his autobiographical memoir, he described how his own regard for animals had developed to a point where, still a young man, he renounced his passion for hunting, and could not even bear to put a live worm on a hook (‘Recollections’, pp. 358, 388). Darwin’s concern for animals aligned with that of many of his countrymen, although it rested on different grounds. The predominant view of animal protectionists was that humans were designed by God to be stewards of all creation; their superior intellectual and moral powers obliged them to safeguard ‘lower’ animals from needless suffering.

In the mid-1870s, charges of inflicting pain on animals were brought against science, in particular the invasive experimentation on living creatures (vivisection) practiced in physiology. Vivisection had been performed in ancient times, but it had increased greatly in the 19th century as physiology became a profession and an integral part of medical and veterinary training. Darwin was clearly disturbed by the prospect of animals suffering for science. In a letter to E. Ray Lankester, he wrote: ‘You ask about my opinion on vivisection. I quite agree that it is justifiable for real investigations on physiology; but not for mere damnable and detestable curiosity. It is a subject which makes me sick with horror, so I will not say another word about it, else I shall not sleep to-night’ (letter to E. R. Lankester, 22 March [1871]). In Descent, Darwin described an animal enduring a painful experiment as an illustration of its tender and sympathetic nature: ‘everyone has heard of the dog suffering under vivisection, who licked the hand of the operator; this man, unless he had a heart of stone, must have felt remorse to the last hour of his life’ (Descent 1: 40).

Darwin’s closest encounter with vivisection came in 1870-71 when his cousin Francis Galton undertook a long series of experiments on rabbits. The investigation was partly aimed at testing Darwin’s ‘hypothesis of pangenesis’, which had suggested that hereditary material resided in tiny particles (‘gemmules’) dispersed throughout the body. Galton acquired different breeds of rabbits and tried to transfuse the blood of one animal to another. Perhaps the characteristics of one breed (white fur) might be passed to another directly? Different methods were tried, including surgically joining the bodies of different breeds together. Galton reported regularly to Darwin on the results (all negative). He eventually presented his findings to the Royal Society, calling into question the theory of pangenesis. Darwin was taken aback, and swiftly replied in a letter to Nature, insisting that he had never stated that gemmules resided in the blood, and that this should have been obvious since he intended his theory to apply to plants. He added, however that Galton’s experiments were ‘extremely curious’, and that he deserved credit for his ‘ingenuity and perseverance’ (letter to Nature, [before 27 April 1871]). When Galton could no longer look after the rabbits (many died from the cold), Darwin offered to give the poor creatures a home at Down, only to return them to Galton as required for further cross-circulation and ‘Siamesing’ (letter from Francis Galton, 13 September 1871).

Several years later, proof for pangenesis was sought in another set of experiments by George John Romanes. This time the creatures were plants. Romanes tried bisecting and grafting different varieties of root vegetables to see if the characteristics would blend. Some of the results were promising, but inconclusive (see letter from G. J. Romanes, 14 July 1875). Eventually Romanes, who had worked on the nervous system of medusa, considered using animals. ‘The world will be much more influenced by experiments on animals than on plants’, Darwin conceded. ‘I think a large number of successful results will be necessary to convince physiologists’ (letter to G. J. Romanes, 18 July 1875). Darwin was concerned that the method be painless, however, and he advised against repeating the procedures of Galton:

With respect to your experiment I should think grafting the ears of rabbits would be almost impossible, as it would be so difficult to keep the animal quiet afterwards. I do not speak of the pain as of course you would do it under chloroform. The comb of the fowl, especially of the Spanish breed is strongly inherited & would be thus well fitted for your work; & I suppose birds can be chloroformed (letter to G. J. Romanes, 27 December 1874).

In the previous sections, we have traced Darwin’s growing interest in physiology and the incorporation of its theories and methods into his research. Some of Darwin’s plant experiments, such as applying toxic substances to the common sundew, Drosera rotundifolia, were analogous to those performed on dogs and other animals. Darwin’s work on insectivorous plants drew him into close contact with England’s leading physiologists, John Scott Burdon Sanderson, Thomas Lauder Brunton, Michael Foster, and Edward Emanuel Klein, all of whom made extensive use of vivisection. This group had jointly authored The handbook for the physiological laboratory (Klein et al. 1873), a two volume work designed for teaching. The book became a focus of criticism because it described a wide range of vivisection procedures for routine use in the training of researchers and medical doctors, and because it failed to recommend, or even mention, anaesthetics. The authors later claimed that this was an oversight, but some eminent physiologists were reluctant to use ether or chloroform because the substances altered respiration, heart rate, etc. and hence interfered with investigations on nerve activity. Indeed, the leading French physiologist, Claude Bernard, advocated curare, which paralyzed the animal without desensitizing it to pain.

Plate from Handbook showing instruments for measuring muscular reflex in the leg of a frog. 

Volume 2 of the Handbook contained several hundred plates, showing instruments, microscopic sections, and tracings of physiological functions, but only one page displayed an animal undergoing experimentation. The creature shown, a frog, was widely used as an experimental animal because its strong muscular reflexes remained functional after extensive cutting, perforating, and even decapitation. But many of the experiments in the Handbook recommended dogs or cats, animals much dearer to the hearts of Victorians than cold-blooded frogs. One of the main strategies of vivisection critics was to expose the ‘horrors’ of the laboratory to the non-scientific public. Here they turned to continental works, including those of Bernard, where domestic animals were readily displayed under the knife. One of the leading voices in the campaign to regulate animal experimentation, Frances Power Cobbe, did not mince words in her articles and pamphlets, targeting some of the most eminent continental physiologists. Extracts from their publications showed animals (mostly dogs and rabbits) strapped to benches and flayed open, mouths prised apart with clamps, baked in stoves or boiled in vats. ‘Do not refuse to look at these pictures’, Cobbe pleaded. ‘If you cannot bear to look at them, what must the suffering be to the animals who undergo the cruelties they represent?’ (Illustrations of Vivisection, 1887, p. 3). These were not exceptional experiments for discovery, she insisted, but ‘stock experiments’ repeated over and over for training and demonstration. Cobbe was an acquaintance of the Darwins, and had corresponded with Darwin cordially about his moral theory, and their mutual admiration for dogs. But Darwin could not support her strident campaign which branded physiologists as ‘demons let loose from hell’ (letter to F. B. Cobbe, [14 January 1875]).

Darwin’s involvement in the vivisection controversy, including the drafting of legislation for Parliament, is described in detail here. He stated his position most frankly in a letter to Henrietta, 4 January [1875].

I have long thought physiology one of the grandest of sciences, sure sooner, or more probably later, greatly to benefit mankind; but judging from all other sciences, the benefits will accrue only indirectly in the search for abstract truth. It is certain that physiology can progress only by experiments on living animals—Therefore the proposal to limit research to points of which we can now see the bearings in regard to health &c, I look at as puerile.

Darwin saw a need for regulation (licensing, inspection), but there were great problems in implementing this. Researchers valued autonomy, and were opposed to outside surveillance and interference. Vivisection’s critics included a number of eminent physicians, highlighting the tension within the medical profession over the authority of laboratory methods and techniques. The debate also pointed to the growing institutionalization of science, the importance of access to laboratories with costly equipment, a supply of animals, etc.. Darwin was concerned that ‘private men’ would be pushed out, ‘young unknown men who are the most likely to do good work’.

I wd gladly punish severely anyone who operated on an animal not rendered insensible, if the experiment made this possible; but here again I do not see that a magistrate or jury cd. possibly determine such a point. Therefore I conclude, if (as is likely) some experiments have been tried too often, or anæsthetics have not been used, when they could [have] been, the cure must be in the improvement of humanitarian feelings. Under this point of view I have rejoiced at the present agitation. (letter to H. E. Litchfield, 4 January [1875])

Darwin worked closely with Burdon Sanderson and Thomas Huxley to draft a bill that would allow vivisection with certain restrictions, specifying the use of anaesthetics whenever possible. He feared that if no action was taken by the physiologists themselves, then Parliament, whose members were woefully ignorant of science, would pass measures that would hinder its progress. I have reason to believe,’ he wrote to Huxley, ‘that experiments are made on animals without the use of anaesthetics, when they could be used, & this I look at as simply atrocious. Though the promoters of the present movement are flagra[n]tly unjust towards physiologists, this is no reason why they and all biologists should not do what can be done to save suffering. … If nothing is done I look at the noble science of Physiology as doomed to death in this country. (letter To T. H. Huxley, 14 January 1875)

Legislation was passed the following year allowing vivisection for ‘original research’ and teaching under certain conditions, but the Bill left many parties unsatisfied and the controversy continued. More radical groups were formed, promoting the total abolition of the practice. ‘It seems to me’, Darwin remarked to George Romanes, ‘that physiologists are now in the position of a persecuted religious sect’ (letter to G. J. Romanes, 4 June [1876]). Experimenters and a portion of the medical profession mounted a more organised defence. To bring more solidarity to the field, Darwin’s son Francis, and a number of his close colleagues (Huxley, Romanes, Galton) formed the Physiological Society. Darwin remained in the background. He contributed a substantial sum (£100) to a ‘Scientific Defence Fund’, originally established to support physiologists who faced prosecution for vivisection. It was later re-branded the ‘Science Advancement Organization’ and then ‘The Association for the Advancement of Medicine by Research’, with the aim of promoting ‘knowledge of the utility of experiment amongst people in general’ (letter from T. L. Brunton, 12 February 1882). Darwin declined the offer to be honorary president (letter to T. L. Brunton, 17 December 1881). The organization had its first meeting on 20 April 1882, the day after Darwin’s death.

While Darwin was actively recruited as a figurehead by experimentalists, and has often been presented as a defender of vivisection, he was clearly divided on the issue. He was unable to perform experiments that induced any suffering, and was happy to leave the underlying physiology to others, incorporating the results of experiments that had been painful and prolonged. The vivisection controversy posed a major public challenge to scientific authority, and exposed divisions within the scientific and medical communities. As one who had always indulged his curiosity, experimenting freely and repeatedly on plants and ‘lower’ animals (e.g., worms), Darwin was now confronted with the moral consequences of the experimental life, and the fate of the animals that were sacrificed for it. What made an experiment worthwhile? Or a product of ‘mere detestable and damnable’ curiosity’? Who should decide?


Cobbe, F. P. 1887. Illustrations of vivisection. Philadelphia: American Society for the Restriction of Vivisection.