Just look at the cover. How refreshing is the idea of a book on marriage and relationships based on scientific study, on falsifiable hypotheses, instead of self-help platitudes and moral/religious aphorisms? Parker-Pope is a former health journalist who got divorced after 17 years and decided to turn her focus on marriages to see what she could have done different. The result is a pretty decent introduction to a lot of the (relatively recent) work that's being done studying marriages, sexuality, and happiness.

Some highlights:

• Women can smell out a preferred partner's scent in from their dirty t-shirts. The "smells" they find most attractive belong to males with specific genes that are most different than those of the women. Incredible! Men cannot do the same. However....
• All else held constant, men will tip an ovulating stripper twice as much as a non-ovulating one, and they'll tip half as much to a women currently on her period. (Hard to imagine exactly how other variables would be held constant here.. but interesting - there's no leading theory on how men are able to sense this).
• Having children pretty much always makes a marriage worse, by about 10%. All the way until they move out. (Kiddos do raise other levels of satisfaction.. probably to a net gain.. but still they always make marriage worse.) The takeaway here: go ahead and have kids if you want them, but don't ever do it to try and save a marriage.
• It costs $240,000 to raise one child to age 18. That doesn't include any opportunity cost either (stalled career, time off work, etc). That's a LOT.
• Disagreement about household duties are a major source of marriage trouble. It's a good idea to work them out equitably among both partners.
• Happiness may be genetic. Typically people spend their whole lives at a pretty constant level of overall happiness. Twins separated at birth are also typically equally happy, despite being raised differently and living in totally different conditions.