The Clapping Ladies

We have come across an interesting phenomenon the we have named "The Clapping Ladies". This is not a very original name as it very much describes the behavior and gender of the person to whom the moniker is applied.  The real question is "Why?" and it's natural corollary "Do they know what they look like?"  Before I continue, let me try to explain the behavior in a bit more detail.  The first indication one has of a Clapping Lady (from here on known as a CL) is the tell-tale sound of a very rhythmic clap.  Upon looking around one will notice a CL (they are always older Chinese women) within a short distance walking at a brisk pace, arms straight and swinging - up "clap" and down, up "clap" and down etc.  There are variations on this basic move.  Sometimes the arm swinging and clapping is done parallel to the ground - known as the "Horizontal Clap" (imagine arms outspread like a gymnast on the rings in the Iron Cross position) where the arms are brought together in front of the person at chest height and parallel to the ground.  The final and rarest variation is the most complex and is called the "Front & Back Clap" which results in a double time rhythmic clap.  We have only observed this one time and think that she might have been a former circus performer due to her extreme flexibility to be able to clap behind her back.  You might imagine that the CLs create quite a scene when out on the street conducting their "business" however no one seems to notice them and they don't seem to be in the least bit inhibited in their activity.  So back to the question of "Why?"  One theory is that this is a form of excercise as the clapping is always done at a brisk walking pace.  Perhaps the clapping promotes blood flow and invigorates the system.  Another theory, is that they have recently lost their way from a percussion ensemble in a street parade, however we lack any evidence of random street parades in Shanghai.  Finally, they may just want to have a little space in this very crowded city.  This seems to be the most likely explanation as there is always about a two meter sphere of space around them regardless of the number of other fellow Shanghainese in the vicinity. To date we have yet to engage with a CL with the exception of imitating their clapping rhythm which did not seem to bother them at all.  One of these days I will try to inquire as to the reason but for now we will continue to listen for the sound of a CL and simply smile at this strange but somehow endearing phenomenon.