Everyone knows what a shrug looks like—in its simplest form, a quick lift of the shoulders. And everyone knows what a shrug means—usually "I don't know" or "I don't care." But why would this movement have this meaning? What does a scrunch of the shoulders have to do with not knowing or not caring?
One tempting answer is that the shrug means what it does because, well, it just does. In other words, it's simply a convention, a cultural pact of the "green means go" variety. Not a terribly satisfying answer. The shrug is not limited to Anglo and European communities—in fact, it has been described as a "candidate gestural universal." Speakers of several African languages—including Yoruba, Hausa, and Luo—have been observed to shrug. So, too, have speakers of Awtuw, Enga, and Yele, three languages in different regions of New Guinea. The gesture is common across the Middle East, and it's been noted in Nepal. Deaf signers shrug, too—whether they are in Greenland, Turkey, Mexico, Israel, or elsewhere. When a gesture is so widely distributed, this strongly suggests it has been independently innovated around the world. And this, in turn, suggests there must be some natural relationship between the shrug's particular form and its particular meaning. What might that relationship be?
Few researchers have ventured explanations. One of the first to do so was Charles Darwin in his treatise on The Expression of the Emotions in Man and the Animals (1872). His interest was not just in the shoulder-lifting aspect of the shrug, but in a full-body, multifaceted display in which the shoulders play only a part (below, at right). Darwin's explanation for the origins of the gesture rests on his "principle of antithesis." This one of three explanatory principles Darwin developed in Expression to account for why expressive acts—smiles and sneers, laughs and yawns, head shakes and nods—take the particular forms that they do. To understand how his explanation of the shrug works, it helps to review the first two of these explanatory principles.
Darwin first observes that forms of bodily expression are often "serviceable"—that is, the particular form they takes serves a clear function (at least in general if not in every case). For instance, when an animal is scared and its hairs stand on end, this action make the animal look bigger and thus more ready to confront a threat. He dubs this the principle of "serviceable associated habits."
Darwin then proposes a second principle of "antithesis." He writes: "Certain states of mind lead to certain habitual actions, as under our first principle. Now 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" (p. 34). As he notes, this involuntary tendency is present even if such opposing movements are not themselves functional.
The shrug is one of Darwin's central illustrations of antithesis. He invites us to consider an aggressive, "indignant" posture in which the body is primed for pugilism (see below, left). Movements of the shoulders, arms, hands, head, and face are all involved. We can then go down these movements one by one, and for each consider what a movement of a "directly opposite nature" might look like. When we do this, we end up with the prototypical shrug display, which thus embodies non-aggression or non-assertiveness. Darwin provides staged photos of both the pugilistic posture (thesis) and the full-body shrug display (antithesis), which I've juxtaposed above for comparison.
The directly counterposed elements seem to be:
1. Shoulders squared.
2. Forelimbs rigid.
3. Fists clenched.
4. Brow lowered.
5. Head erect.
1. Shoulders raised.
2. Forelimbs relaxed, outspread.
3. Palms open and up.
4. Brow raised.
5. Head to one side.
Some will no doubt find this explanation implausible—too cute, too "just so." Clever as it is, my initial response was skeptical, too. But I've come around to taking it a bit more seriously, in large part because alternative explanations are scarce—and, perhaps you'll agree, scarcely more compelling. Let's have a look at four others I've found.
A related explanation is suggested by David Givens in a 1986 paper—'The Big and the Small.' He describes the shrug as a kind of primitive crouch, a way of burying the head in the shoulders and thus, in effect, shrinking. He writes: "When people cannot answer a question, or cannot perform as expected, they shrug and thereby seem 'small'. To appease, in effect, a person becomes minimal and mere by symbolically 'crouching.'" (p. 157). Both Darwin's and Givens's proposals thus see the shrug as built from primitive action patterns—the kind of instinctive impulses that people are not necessarily aware of.
Others have also pursued the idea that the shrug is a kind of bodily metaphor. One such proposal, offered by Adam Kendon (2004, p. 275) and Jürgen Streeck (2009, p. 189-90), is that the shrug signifies an embodied "withdrawal" from some line of action or state of affairs. The key bodily component of the display in this account seems to be, not the hunched shoulders, but the spreading out of the arms and opening of the hands, as if making this movement represents pulling back from some pursuit. (Streeck also notes that the raising of the shoulders and lifting of brow might signify disengagement).
Calbris (2011) also sees the shrug as bodily metaphor, but zooms in on the shoulder-raising component specifically. She sees this movement as representing the act of dislodging an "annoying object" with a jerk of the shoulder. The explanation seems tailored to a particular use of the shrug in French culture, in which the speaker casts something as insignificant, a pest to be dispatched.
All these explanations have a certain fanciful quality. And my favorite explanation of the shrug—for sheer puckishness, if not plausibility—goes even a further in this direction. It was ventured by the physician William Main, who, in correspondence with Darwin after the publication of Expression, advocated his own theory of the importance of "lines" in bodily communication. In a first letter, penned in November of 1872, he writes: "Observing the effects of the direction of lines has been a favourite amusement of mine for years & I am forced to the conclusion that the expression in the direction of Lines is the only universal language of Man & the higher Animals."
Darwin coolly rebuffs this line of speculation, but Main persists. In a subsequent letter, Main extends his theory of lines to the case of the shrug: "Whenever a disharmony of lines is observed therefore, we are struck by the incongruity… [W]hen a man shrugs his shoulders, the eye brows are raised, & the mouth angles depressed; the head is tilted downwards to one side, & the shoulders are raised; the upper arm is drooping close by the side, & the fore-arm & fingers are spread out at right angles to the body—the whole powerfully expressing a puzzled state.” The jumble of lines, in other words, offers a visual metaphor for the shrugger's perplexity. History records no response from Darwin.
So why do shrug? The short answer is, I'm afraid: ¯\_(ツ)_/¯. The origins of this familiar gesture—a candidate human universal, now enshrined in emoji and GIFs—remain elusive. At least five explanations have been put forth—Darwin's antithesis, Givens's crouch, Kendon's withdrawal, Calbris's jerk, and Main's jumble—and none obviously wins the day. And yet, fanciful as they may seem, one or more of these explanations may well contain the seeds of an answer.
1. Thankfully, the shrug has re-emerged as a topic of interest among gesture researchers. For some valuable recent discussions, see Debras (2017), Jehoul et al. (2017), and our own just-out review paper, 'The palm-up puzzle.'
2. For the idea of the shrug as a "candidate gestural universal," see Streeck's Gesturecraft (p. 189).
3. If the shrug is as rich and multi-faceted a display as Darwin contends, why is it so narrowly associated with the shoulder action in everyday language? (see, e.g., how the folks at Merriam-Webster define it). Most likely this is because each of these other features is used for other gestures, and does not on it's own have a crystallized meaning. The shoulder action is the most distinctive aspect of the gesture, in other words.
4. Darwin's idea that some aspects of bodily expression are "serviceable" has recently found support. See, e.g., an article by Joshua Susskind and colleages, 'Expressing fear enhances sensory acquisition.'
5. The original Plate VI, which included four figures, can be found here.