At a concert last night I was applauding the performance, when it struck me - not for the first time - what a curious thing it is to show appreciation by whacking one's hands together repeatedly. How long (to the best of our knowledge) have we been clapping? And is the origin known?

In the great academic tradition of paying people large amounts of money to devote years of their life pursuing knowledge whose contribution to the sum of human intelligence is questionable at best, the authorities in Uppsala University in Sweden commissioned a whole team of researchers a few years ago into answering this very question. They failed to come up with an origin except to agree that it is very old indeed and can be traced back to the earliest written records. However they did make a pretty good stab at affirming not only how ancient a habit it is but also why. Apparently it is to do with a principle called "social contagion" which manifests itself most clearly in making communal noise together to express a common view. It is easier to find examples of communal disapproval. However the same principle applies to approval and the communal challenge has always been how to noisily express approval that cannot be confused with the opposite, and using of course the tools available at all opportunities (voice and appendages).

All of this makes perfect sense until one then visits a Swedish auditorium and sees what exactly they're talking about. Like all Scandinavians (and some Northern European cultures) Swedish appreciation through applause is almost always performed in a synchronised fashion with everyone clapping at the same time. To other people's ears this sounds way too regimented and lacking spontaneity, in fact ominously like the derisive "slow hand clap" which through social contagion is used to communally express extreme disapproval in other cultures. Which of course raises the questions of how on earth this disparity arose, where did the slow hand clap originate, and crucially which came first?

I may have dreamt this or just imagine I remember it but, isn't there something called swimmers' fire, a slow and rhythmic hand clap that builds to a crescendo before or maybe after a race?

I was briefly put to wondering about what other 'appendages' might be used to produce a noise, manipulation of most of these may be visually but not aurally arresting, but then I recalled that one society I belong to traditionally acknowledges new members by foot stamping.

Fascinating.  I suppose it makes sense that you would want to make noise in approval, and this could be 'contagious'.  I hadn't heard about the Swedish manner of clapping; very curious.
I'm not familiar with the name, but I have come across the crescendo type of clapping, usually to encourage someone about to compete or perform in something. I've also come across foot-stamping, but usually to emphasise coventional clapping rather than as an alternative.

In Tibet (and particularly among Buddhist monks) the clapping of hands is used for emphasis while debating. Claps are employed as sort of rhetorical bullet points.

In wider Tibetan society, clapping is said to be used to ward off evil spirits although this custom is seemingly archaic and perhaps even apocryphal. Any concerns regarding the academic authenticity of this, however, didn't stop it from featuring in a memorable scene in Jean-Jacques Annaud's 1997 film Seven Years in Tibet.

In some parts of South America, clapping your hands at someones gate replaces ringing the doorbell or knocking on the door.