Leslie Brothers attached electrodes to the brain of a monkey which was watching videotapes of the face of another monkey. She found neurons selectively responsive to the other monkey’s facial expression of emotions. An identical behavior is found in human infants where the selectively repond to expressions on adult faces.
A child invariably stares longer at an object that you drop out of your hand, but does not fall down. Somehow, it knows that all objects are supposed to fall to the ground - gravity. We all are prejudiced even before birth, that the light (sunlight) always comes from the top, which is why the same shaded-circle appears bulged when seen at an angle & depressed when seen upside-down.
All these support Darwin's view that emotional & cognitive behaviors are remnants of actions that were functional in evolutionary history. Since the feeling of self-awareness & consciousness is invariably linked with emotions, this suggests that the notion of Self itself might be an evolutionary functionality.
On the other hand, William James held that emotions are internal perceptions of physiological processes in our own bodies — tense facial muscles, sweaty palms, and especially the effects of the autonomic nervous system, such as a pounding heart, faster breathing, and higher blood pressure. Recent works on Somatic Theory by Antonio Damascio also strongly uphold this view. This seems to suggest a bodily (somatic) source for Self.
In a very different plane, Donald Griffin has studied the mental abilities of insects and animals. He associates consciousness with complex and novel behavior in changing or unfamiliar circumstances. For instance, Bees can communicate the direction and distance of food sources and can distinguish between water, nectar, and a possible hive site; they do their waggle dance only when other bees are around, but they have limited ability to modify their behavior in new circumstances. African Grey Parrots can talk excellently but they fail to comprehend the meaning of Self. They often refer to themseves in third person saying - "Polly needs water" instead of saying "I need water". Some apes can recognize parts of their body in a mirror & even communicate to some extent symbolically & even with the use of sounds. But their communicative abilities are greatly dwarfed in front of that found in humans to reveal anything more than evolutionary impressions of Self.
But works of Griffin & others bring out a curious observation - the notion of Self began to emerge only after organisms started to indulge in a social life. Greater the complexity of social interactions & social needs, the more expressed the recognition of self & our feelings towards it.
Though there are many such alternate views to view the source of emotions, self & consciousness, they don't seem to be in contradiction with each other. They just seem to be talking about the same source, seen from different angles. Will all the views converge? Can there be a unified theory for defining everything that is human?