1. Meaning of happiness seems to depend on individual's estimate of his/her life expectancy. It would be interesting to run a series of thought experiments on "what would happiness be if you were to live 10years; 20yrs; 30yrs;40;60;80;100;150;300;1000?" Check for qualitative changes on the timeline.

2. Happiness: A History by Darrin M. McMahon

3. High divorce rates. Why? If people were "designed by evolution" to live till about 30-40 with imminent danger of death from childbirth (women), violence (men), desease(children), then monogamy seems to be a cultural patch on a biological problem. Serial monogamy.

4. would be interesting to trace evolution of prayer.