Hehe, sorry, I forgot to add more. Seriously though, the extroverts have the edge in evolutionary terms because social cooperation is facilitated more through increased interaction to form bonds relations and bonds with others and increase the likelihood of help for survival when you need it. So we introverts get bumped down by comparison because its harder for us to compete for interactivity with others because we're not driven to be going out and meeting lots of people for that to occur. The more people that care for you, more likely to help you, and that increases with more people encountered and interacted with.