When Did Humans become Aware of themselves?

While reading a paragraph on self in the book "Living Issues In Philosophy - Sixth Edition" by authors Harold H. Titus & Marilyn S. Smith, I started to wonder when did we first developed this self-awareness?

What is Self-Awareness?
According to http://www.yourdictionary.com/, self-awareness is a person's knowledge of themselves and their worth as a person.

When did we first inherited it?
According to the book of Genesis, Adam and Eve became "aware" after eating from the Tree of Knowledge - which is fine but I would like a more scientific side of it based on the theory of evolution.

The man of today is very different than the monkey counterpart in terms of mind and thinking. At which point, of the evolutionary process, did man start to be aware of himself? The popular belief is that it developed over time once our ancestors started using tools while others believe it was when we started to have the desire to communicate with each other.

What have you heard on the origin of Self-Awareness?