Thumbs up (gesture)

A thumb signal, usually described as a thumbs-up or thumbs-down, is a common hand gesture achieved by a closed fist held with the thumb extended upward or downward in approval or disapproval, respectively. These gestures have become metaphors in English: "The audience gave the movie the thumbs-up" means that the audience approved of the movie, regardless of whether the gesture was actually made. The term itself is an Anglo-Saxon word indicating the measure of a clenched hand with the thumb extended.

The source of the gesture is obscure, but a number of origins have been proposed.

Carleton S. Coon, having observed Barbary apes in Gibraltar using the gesture, hypothesised in the anthropological classic The Story of Man that it is a mutual celebration of having opposable thumbs. Critics have suggested, however, that the apes may be simply imitating humans.

The Latin phrase pollice verso is used in the context of gladiatorial combat for a hand gesture used by Ancient Roman crowds to pass judgment on a defeated gladiator. In modern popular culture, it is assumed that "thumbs down" was the signal that a defeated gladiator should be condemned to death; "thumbs up", that he should be spared. The latter view was popularized by a widely reproduced painting by the 19th-century artist Jean-Léon Gérôme, whose Pollice Verso (usually known in English as "Thumbs Down") depicts a triumphant gladiator looking up into the stands for the verdict of the crowd.

"Now they give shows of their own. Thumbs up! Thumbs down! And the killers, spare or slay, and then go back to concessions for private privies" from Juvenal's Against the City of Rome (ca. 110–127 B.C.)

While it is clear that the thumb was involved, the precise type of gesture described by the phrase pollice verso and its meaning are unclear in the historical and literary record. According to Anthony Corbeill, a classical studies professor who extensively researched the practice, thumbs up signalled killing the gladiator while "a closed fist with a wraparound thumb" meant sparing him.

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