For a long time, i've been wondering about this obvious yet intriguing phenomenon. The question which got me started was.... Q:When a normal person is introduced to sudden physical pain(preferably sharp), why does he\she shout? We know that it is an involuntary action, but why does the body engage that involuntary action? I've come up with a theory of my own. Here goes:- For instance, let us assume that you have a vessel of boiling water(say >400k). You insert your finger into the hot water. As the kinetic energy of the molecules inside the vessel is very high, the energy gets transferred to your finger as the molecules collide on your finger. Now, (Here's the fussy part) assuming that the energy gained by your body in this process is not negligible w.r.t the enrgy already contained in your body, the newly acquired energy will disturb the body's Energy-stability equilibrium, causing the body's stability to decrease(as we know stability is inversely proportional to energy). To regain the body's instantaneous loss stability, the body has to engage a mechanism through which it can *quickly* loose energy. And that mechanism,ladies and gentlemen,is nothing but the release of energy to the air molecules around your voice box which is termed as 'shouting'. Now my theory can be assumed valid, taking into considerstion the fact that the amount of energy acquired is directly proportional to the intesity of your shout( if you think i'm kidding try it on yourself) The limitations of my theory are obvious. 1)It has a very complex system associated with it, i.e. human body. 2)I can't assume the numerical values i.e. energy contained in our body. etc. which makes mathematical calculations difficult. 3)I can't reason instances where there is blood loss eg. Pin prick. It'll be really helpful if someone gives me the figures. I've just made a qualitative analysis of this phenomenon. Ragav. cheers.