What is this natural need when we are at a loss for words to go "Errrm"?. I therorised that the 'word' is adopted to let others know that you are thinking and that you are still communicating and do not want the spot light to leave you so you have to regain attention. But who knows if this is the truth. So I was wondering if it is that or simply just some natural native noise we make to let others know we are still there :?.