I can explain that though. In primitive societies people have very strong bonds with everyone around them, and families live close. Competition may increase productivity, but it makes people slightly less happier because of the stress. In primitive societies, if you have any problems, your tribe will always be there to help you out. Not to mention that strong culture and religion give answers and hope to people.
I am not saying that i want us to leave civilization, but a primitive person's average day is probably happier then the average person in any industrialized nation.
Civilization is better though, for the reasons I listed in my other posts, don't worry capitalism and economic growth is good. (for now)
and if you read my posts through, you would see that I agreed that a higher life expectancy allows people to live longer. However, living longer doesn't make your life any happier, but it makes life overall more worth living.