You can’t be happier than the person you’re with. I’ve tried. It doesn’t go over well. Scott Adams

Why did evolution makes us (sometimes) happy? One standard story, and in fact the only story I’ve found so far in a quick search, is that happiness is just our mind’s way of telling us what we want. We consciously want to be happy, and so to direct our behavior our subconscious tells us that we are happy doing what it wants us to do.

But this can’t be the whole story. Not only are we well aware of wanting as a different feeling from happiness, we know of many systematic differences between our wants and our happiness. For example, even though we expect these choices to make us less happy, we expect we’ll pick money over sleep, shorter commutes, leisure time, friends, family, and legacy. We’ll pick school over a social life, and a career-helping internship over interesting one. And we’ll pick attending a favorite musician’s concert over a friend’s birthday party or reporting a crime. (Source) Two other fascinating cases:

To reconcile the intuition that Americans today are better off than in the past with the finding that average SWB [= subjective well-being] has remained flat in the U.S. over the past decades, we ask respondents to rank being born in 1950 versus being born in 1990 in both choice and SWB questions. Although our respondents overwhelmingly favor being born in 1990 in both questions, more choose 1990 despite believing that they would be happier in 1950 than the reverse. …

To reconcile the intuition that expanding political and economic freedoms for women have made women better off with the finding that average SWB among women has declined in the U.S. since the 1970s, both absolutely and relative to men, we ask respondents to rank living in a world with or without these expanded freedoms for women. Again, significantly more respondents choose a world with these expanded freedoms for women in spite of believing that a world without them would make them happier than the reverse. (more)

These all seem to me reasonably consistent with our thinking we’ll be happier doing what others approve, and what connects us to them. Our visible happiness functions in part to convince our associates that that we care about their approval and contact. This fits with smiles, taken as an indicator of happiness, also being seen as signs of submissiveness – athletes and runway models rarely smile in photos. (More on smiles)

This seems similar to a plausible theory of pain, that pain is in part a call for help from associates:

Certain types of [human] pain are not associated with any physiological damage, and studies that show the presence of others can affect reported sensations of pain. Labour pain is another good example. Across all human cultures, there are nearly always helpers, from relatives to medical professionals, who attend births. … By contrast, among our primate relatives, solitary birth is the norm. Human childbirth appears to be uniquely painful among members of the animal kingdom. … I suggest that protracted labour pains make us show distress and recruit help from others well in advance of the birth – a strategy that offers a survival advantage. (more)

Added 6:30p: Calls for people to be happy, and to teach them what leads to happiness, can be seen as calls from associates to attach yourself more strongly to them and conform more strongly to their norms and pressures.

Added 12May: Bryan Caplan correctly points out that in the last two cases above, of being born earlier and women’s rights, it is choices that are in the direction of doing what others approve and connecting to them. Happiness goes against those things there. Bryan also suggests that we tend to choose money and status over happiness because of social pressure to work hard and succeed. In this view athletes and runway models don’t smile as a signal of having sacrificed happiness for status. This all makes sense; it seems I was just confused.

But Bryan’s account raises the question of why happiness doesn’t encode our value for status and social approval, as it encodes so many other values. Bryan suggests that this is because “foragers tend to act on impulses that farmers strive to suppress.” Somehow the transition to farming changed the values we use to chose actions in a way that wasn’t reflected in the processes by which our minds compute happiness. But surely foragers had to deal with social pressures and status; those issues arose long before farmers. So there seems to be more to this story that we don’t yet understand.