Love this response Andy. I searched on a few articles pertaining to why humans are driven to share. I didn't find anything particularly substantive, but my instincts point to the following:
Like you said, give our lives greater significance
Be validated (the reason we so quickly go back to check to see who "liked" our posts)
Feel connected (companionship, being connected to a larger community)
Be considered a thought leader
Be perceived/associated with a certain topic
I am guessing this is all connected at its most fundamental to Maslow's hierarchy of needs - in the self actualization section of the triangle.