If our expectations of happiness sometimes fall short. it may be because we often misunderstnad the nature of emotions in general. We tend to think that emotions come in pairs, that each pleasant emotion has its distressing counterpart, that happiness can alternate with sadness, bravery with fear, contentment with  frustration.

In How the Mind Works, Stephen Pinker says not so fast. Emotions don’t come in pairs. “There are twice as many negative emotions (fear, grief, anxiety, and so on) as positive ones.” If you don’t believe this, count the common unpleasant emotions that come to mind, then try to think of the same number of positive ones.

Another clue that emotions don’t come in matched positive and negative versions is that “[P]eople’s mood plummets more when imagining a loss in their lives (for example, in course grades, or in relationships with the opposite sex) than it rises when imagining an equivalent gain.” Pinker quotes tennis star Jimmy Connors: “I hate to lose more than I like to win.”

So, the hard news is that unpleasant emotions are both more plentiful than upbeat ones and they pack a stronger punch as well.

How and why did evolution endow us with such a gloomy set-up? You might think this mood arrangement couldn’t do much to support our survival. But apparently it does just that. The benefits of happiness and the other positive feelings are, in evolutionary terms, more limited than we might think. Pinker: “The psychologist Timothy Ketelaar notes that happiness tracks the effect of resources on biological fitness. As things get better, increases in fitness show diminishing returns: more food is better, but only up to a point. But as things get worse, decreases in fitness can take you out of the game: not enough food, and you’re dead” (392).

In other words, the dangers of injury, illness, and enemies call for varying levels of distress to signal the seriousness of the threat—emotional smoke alarms that can grow louder and last longer as the threat intensifies. But the joys of health, sociability, creativity, and even spirituality don’t come with the capacity for such intensification. In the long run, we wouldn’t gain from endless gains in gladness. And too much joy for too long and we let our guard down.

So we may not like to think of ourselves this way, but for our own good we care more about what could go wrong than about what is going well. .