[stonewhite]

VS Ramachandran has an interesting talk about mirror neurons, which is a subset of motor neurons. They activate when you perceive anybody else doing something as opposed to only activating during your actions. This is fundamentally a built-in empathy/group learning mechanism, but it also has some other interesting implications too.

For example, when somebody touches someones hand in your view, your mirror neurons activate just like you yourself have been touched. Then your nerve endings in your hand send a signal to cancel the effect, but sometimes you still get a tingling from the neural confusion depending on the strength of the signal (e.g. watching someone getting kicked in the balls or russian daredevils walking on top of highrises). But, if there is no nerve endings there, there is nothing to cancel the signal, so you do experience another persons feeling of being touched as your own. Therefore, the only thing that separates our consciousness is literally our skin and our nerve endings on it.