Across the world, and throughout recorded human history, nonverbal communication has helped characterise cultures as much as (and sometimes more than) actual spoken or written languages have. China is no exception.

Many Chinese hand gestures developed from stylised religious signals, or mudras, commonly used for non-verbal communication by Buddhist monks who spoke mutually incomprehensible languages. While most laypeople could recognise many of these signals, the more esoteric mudras were known only to Buddhist initiates; the most complicated forms remained unknown to all but very senior abbots.

Accordingly, various mudras – or versions of them – could be used for clandestine communication. Chinese secret societies, unsurprisingly, made great use of these obscure signs. By a few quick digital gestures, a Triad member on the run, disguised as a wandering Buddhist monk, could swiftly ascertain who were his confederates and who to avoid. In much the same way, Catholic monks in medieval Europe could travel from one end of the continent to the other and gabble away to each other in Latin; most people around them remained ignorant of anything they said beyond the standard words used to celebrate mass. Likewise, the Freemasons’ otherwise innocuous code words, and peculiarly gripped handshakes, provide discreet recognition and acknowledgement of rank between members.

Handshakes – or their equivalent – have also altered with the passage of time. Historically, the Chinese never shook hands; greetings involved clasping one’s hands together and moving them up and down vertically, usually accompanied by a bow. Like any gesture learned in adulthood from widespread mimicry of a foreign culture, rather than acquired from infancy as part of one’s own cultural furniture, Chinese handshakes generally differ from those given by Westerners in one key respect. Often the hand is touched, rather than grasped, and the resultant limp, “wet fish” gesture is negatively remarked upon by the unsuspecting. Some Chinese hand gestures require specific cultural knowledge to interpret. Numbers, for example, are formed by the fingers, in sketched approximation of the written character. Other common gestures have gradually changed as time moves on.

Like any historical document, old films can be used to understand how people in the past spoke, moved and gestured. In this respect, films are important cultural and historical documents. Written accounts seldom record such “trivial” details; photographs, ultimately, are merely frozen images – frequently posed – that only capture a specific moment in time.

Popular films also show the evolution and decline of gestures over time; what were commonplace gesticulations in the 1930s, for example, had become rare only a couple of decades later. One once-commonplace Chinese gesture used to indicate oneself, often at times of surprise, was the index finger pointed directly at one’s own nose. “Who? Me?” the gesture emphatically implied.

Watch any old Cantonese film to see what I’m talking about. In today’s television dramas – and in everyday life – that gesture has almost vanished, except when done for self-conscious irony, or a comically mocking dramatic effect.

Modern Hong Kong people deploy the usual rude “universal gestures” commonplace to cultures the world over. The middle finger raised abruptly, and accompanied by a scowling face and shouted crude oath, carries much the same coarse, deliberately insulting meaning wherever it is deployed.

For more on Hong Kong history and heritage, go to scmp.com/topics/old-hong-kong