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In the recent exhibition ‘The Beautiful and the Damned’ at the National Portrait Gallery, in London, I noticed some of Guillaume Duchenne's (1806-1875) original photographs showing how expressions could be mimicked by galvanic stimulation of the facial muscles. This caused me to read Darwin's The Expression of the Emotions in Man and Animals. The first edition was published in 1872, thirteen years after the Origin of Species and one year after The Descent of Man. Darwin had, however, been collecting material since 1838. His intention was to show how the expressions of the emotions in man were analogous to those in animals, supporting his theory that man and animals were derived from a common ancestor.
On opening the book I was delighted to find that Darwin had reproduced many of Duchenne's photographs; particularly striking was the comparison, in the same man, between a normal smile and the ghastly grimace produced by galvanic stimulation (Figure 1). Throughout this essay I refer to the third edition, edited by Paul Ekman and published in 19991. This contains changes that Darwin wanted but his son Francis chose not to include in the second edition published seven years after Darwin's death.
For his book Darwin corresponded with or had read the works of some of the most eminent scientists of his day. He quotes extensively from Herbert Spencer and the psychiatrists Sir James Crichton-Browne and Henry Maudsley. He corresponded with missionaries, colonial officers and others in Africa, America, Australia, India, Malaya and New Zealand, on the modes of expression of the emotions in the indigenous people of these regions. The Rajah of Sarawak wrote to him about the Dyaks of Borneo.
Darwin expressed his special indebtedness to Sir Charles Bell for his book The Anatomy of Expression (1844), to Guillaume Duchenne for his Mécanisme de la Physionomie Humaine (1862) (Duchenne was a pioneer of electro-physiology) and to Friedrich Henle for his anatomical drawing of the facial muscles in his Handbuch der systematischer Anatomie des Menschen (1858). Darwin was familiar with anatomy and physiology, having spent two years as a medical student in Edinburgh; there he found that anatomy ‘disgusted’ him, but he wrote in his autobiography, ‘It has proved one of the greatest evils in my life that I was not urged to practise dissection, for I should soon have got over my disgust; and the practice would have been invaluable for all my future work’2.
In addition to the mass of information from these sources Darwin made his own observations on animals, particularly the apes and monkeys (Figure 2), in the London Zoo, a short walk from No. 12 Upper Gower Street (‘Macaw Cottage’), where he lived after his marriage to Emma in January 1839. (Upper Gower Street is now North Gower Street and the site of the Darwin Lecture Theatre, University College.) He describes the development of his first child, William (‘Willy’), born in December 1839, in a diary published in 1877 as ‘A biographical sketch of an infant’3.
The Expression of the Emotions in Man and Animals begins with a review of previous work. Then follows a laborious and unsatisfactory classification into three principles: ‘serviceable associated habits’; ‘the principle of antithesis’; and ‘the principle of actions due to the constitution of the nervous system, independently from the first of the will, independent to a certain extent of habit’. The first principle is explained as follows:
‘Certain complex actions are of direct or indirect service under certain states of the mind, in order to relieve or gratify certain sensations, desires, etc.; and whenever the same state of mind is induced, however feebly, there is a tendency through the force of habit and association for the same movements to be performed, though they may not then be of the least use’.
He explains that these actions may be partly suppressed by the will, and that through constant use complex movements may be facilitated—‘the conducting power of the nervous fibres increases with the frequency of their excitement’. Darwin regarded these movements as inherited and instinctive. He illustrates this principle in man by the shutting of the eyes or the shaking of the head on describing a horrid sight. In dogs and cats he cites the scratching with their paws as if to cover their excreta with earth. He writes, ‘we can understand how the associated movements were acquired through habit’, a statement to which I will return.
On his ‘principle of antithesis’ he explains that ‘when a directly opposite state of mind is induced, there is a strong and involuntary tendency to the performance of movements of a directly opposite nature, though these are of no use’. In man, he cites the shrugging of the shoulders to express impotence or an apology. In the cat, he describes the arching of the back, with the tail erect and ears pricked, as evidence of affection, in contrast to the crouching position, with tail extended horizontally, of an angry cat. In both these categories Darwin proposes that the expressive movements were originally performed voluntarily and only later, through repetition as habits, became involuntary and inherited. This is a curious opinion since it seems to accept the inheritance of acquired characters—the opposite to the acquisition of behaviour patterns through selective pressure.
The third principle is even less satisfactory. Darwin describes it as follows:
‘... that certain actions, which we recognise as expressive of certain states of mind, are the direct result of the constitution of the nervous system, and have been from the first independent of the will, and, to a large extent, of habit.... Our present subject is very obscure, but, from its importance, must be discussed at some length; and it always is advisable to perceive clearly our ignorance’.
Examples of the direct action of the nervous system are trembling, induced by cold, fear, excitement, or muscular exhaustion; and sweating, a reaction to fear or pain. Elsewhere he cites a Mr Bartlett who had observed that a female hippopotamus was covered with red-coloured perspiration whilst giving birth to her young. This is a very odd observation and one wonders if the red colour was due to mud. Darwin is clearly not happy with his classification and writes, ‘It is however, impossible to decide how much weight ought to be attributed, in each particular case, to one of our principles, and how much to another; and very many points in the theory of expression remain inexplicable’.
In the remainder of the book, he discusses the means of the expression of the emotions in animals and in man. It is surprising to find that he considered that ‘domestic dogs, and even tamed jackals, have learnt to bark, which is a noise not proper to any species of the genus, with the exception of the Canis Latrans [the prairie wolf, or coyote] of North America, which is said to bark’. Presumably he had never heard a dog fox barking in the mating season. I am glad to see Darwin supporting what he calls ‘grinning’ in dogs, something I have noticed in our own dog when pleased at the prospect of a walk. He describes it thus, ‘the upper lip during the act of grinning is retracted as in snarling, so that the canines are exposed, and the ears are drawn backwards; but the general appearance of the animal clearly shows that anger is not felt’. Sir Walter Scott's ‘famous Scotch greyhound, Maida, had this habit’. To emphasize the point Darwin quotes from The Chase by Somerville (1675-1742):
‘And with a courtly grin, the fawning hound Salutes thee cow'ring, and his wide op'ning nose Upwards he tilts and his large sloe-black eyes Melt in soft blandishments and humble joy.’
In the section on man, Darwin judges that expressions of emotions are best studied in the insane because their emotions are more fixed and exaggerated; he quotes Sir James Crichton-Browne's description of patients with ‘melancolia’ (depression) and ‘hypochondria’ as showing the contraction of what he calls the grief muscles, causing a transverse furrow across the forehead. On the subject of laughter he writes ‘There is another large class of idiots who are persistently joyous or benign, and who are constantly laughing or smiling’. Probably he is referring to Down's syndrome; it is curious that neither he nor Crichton-Browne seems to have been familiar with the syndrome described by John Langdon Down in 18624.
The most interesting chapter is devoted to blushing, which he describes as ‘the most peculiar and the most human of all the expressions’. Blushing is entirely involuntary and cannot be inhibited. The young blush more freely than the old, and women more than men, but it does not occur in infants though ‘infants at a very early age redden with passion’. Darwin suggests that the tendency to excessive blushing is inherited. Wishing to learn how far down the body blushes extend, he consulted Sir James Paget, the physician and pathologist, who attended to the point for two or three years: ‘He finds that with women who blush intensely on the face, ears, and nape of the neck, the blush does not commonly extend any lower down the body’. Paget told Darwin of an instance ‘in which a little girl, shocked by what she imagined to be an act of indelicacy, blushed all over her abdomen and the upper part of her legs’. According to his correspondents in various parts of the world, all races of man blush. Darwin quotes Buffon, the French naturalist, as having observed that an albino ‘negress’ ‘showed a faint tinge of crimson on her cheeks when she exhibited herself naked’. Darwin considers that the extent of blushing depends partly at least on the area of the body with which the mind is concerned. In support for this theory he cites evidence that ‘with the races of men who habitually go nearly naked the blush extends over a much larger surface than with us’.
In discussing his ‘theory of blushing’ Darwin advances the proposition that ‘attention closely directed to any part of the body’ causes a dilatation of the skin capillaries of that part. Once again he advances the idea of the inheritance of an acquired habit: ‘By frequent reiteration during numberless generations, the process will have become so habitual, in association with the belief that others are thinking of us, that even a suspicion of their depreciation suffices to relax the capillaries, without any conscious thought about our faces’.
This is an intriguing and entertaining book, but it lacks the authority of the Origin of Species and The Descent of Man, and the intimate and endearing observations of, for example, The Power of Movement in Plants and The Formation of Vegetable Mould, Through the Action of Worms. It is as if Darwin had collected a mass of material and sought to rationalize it with a classification in which he seems to have little confidence. Konrad Lorenz, writing in 1965, thought that ethology ‘has a special right to claim Charles Darwin as its patron saint’5, but the science of ethology seems to have veered away from Darwin's approach and is more concerned with behaviour patterns than with the expression of emotions. It is puzzling that Darwin, having accepted that the majority of expressions of emotion are inherited, seems to favour their origin as acquired habits rather than natural selection. However, either way it is difficult to see what advantage to man, whether through selection or through an acquired habit, could come from the phenomenon of blushing. On a more positive note, it is doubtful whether Darwin's scrupulous description of the manifestations of emotion in animals and man, and the variations between individuals and races, has ever been bettered.