Book: The Expression of the Emotions in Man and Animals

Overview

Charles Darwin’s The Expression of the Emotions in Man and Animals (1872) examines how facial movements, postures, and vocalizations reveal internal states, arguing that human and animal expressions share common evolutionary roots. Building on his broader theory of descent, Darwin proposes that emotional displays are not arbitrary cultural inventions but largely inherited patterns shaped by natural selection and conserved across species. The book maps the continuity from infant reflexes to adult signals and from human expressions to those of dogs, cats, horses, and monkeys, thereby undercutting claims of human uniqueness in the realm of emotion.

Method and Evidence

Darwin triangulates evidence from several sources: close observation of animals and children; case notes on people born blind; questionnaires sent to missionaries, travelers, and colonial officials across the globe; and photographic plates, notably those of Duchenne de Boulogne, capturing facial musculature in action. Convergence across these lines, especially the similarity between sighted and blind individuals, supports his thesis that core expressions are innate. He also pays attention to physiological accompaniments such as gooseflesh, blushing, pupil dilation, trembling, and respiratory changes, treating them as expressive residues of nervous system processes.

Three Principles of Expression

Darwin organizes his explanations around three principles. The principle of serviceable associated habits holds that movements originally useful for action, such as baring teeth in preparation to bite or widening the eyes to improve vision, become linked to the emotion that elicited them and persist as signs even when no action follows. The principle of antithesis explains why opposite mental states produce opposite movements: the confident dog stands erect with raised hair and tail; the friendly, submissive dog crouches, lowers ears, and wags. The principle of the direct action of the nervous system attributes certain expressions to diffuse physiological discharge, as when fear induces trembling or piloerection without any obvious utility.

Specific Emotions and Their Displays

Darwin devotes chapters to grief, joy, fear, anger, disgust, surprise, pride, shame, and related states, tracing their muscular patterns and bodily accompaniments. He describes the furrowed brow and downcast mouth corners of sadness; the raised cheeks and eye wrinkling of genuine smiles; the dilated eyes and retracted head of surprise; and the flared nostrils, sneer, or averted gaze of contempt and disgust. Laughter and weeping receive extended treatment: laughter emerges from rhythmic expirations and facial contractions that may have evolved from play signals in social mammals, while emotional tears, though puzzling in utility, are linked to infantile reflexes and later co-opted as social signals. Blushing is singled out as uniquely human, tied to self-attention and the imagination of others’ regard, showing how social cognition penetrates physiology via capillary dilation.

Cross-Species and Cross-Cultural Continuities

Comparisons with monkeys, cats, dogs, and horses highlight shared elements such as hair erection in fear, lip retraction in aggression, and ear and tail postures for signaling approach or avoidance. Reports from many regions indicate that frowns, smiles, and expressions of fear and anger are widely recognizable, even if cultural norms shape when and how they are displayed. Similarities in individuals blind from birth, who cannot learn expressions by sight, further suggest an inherited basis.

Significance

The book anchors emotion in biology while preserving room for cultural modulation, establishing a framework that later informed ethology, psychology, anthropology, and the science of nonverbal communication. By combining evolutionary reasoning with photography, developmental observation, and cross-cultural survey, Darwin provides an early model of interdisciplinary research. The central claim endures: expressions are adaptive traces of our evolutionary history, intelligible because humans and other animals share both emotions and the bodily mechanisms that display them.