It turns out that emotional diversity was a good thing (in terms of being associated with less depression etc.) for both positive and for negative emotions. This seems a little counter-intuitive. You might have expected that feeling many negative emotions would be worse than only feeling one of them – but in fact, it’s better.
The authors speculate that it could be due to the same resilience that biodiversity confers. They also suggest:
experiencing many different specific emotional states (e.g., anger, shame, and sadness) may have more adaptive value than experiencing fewer and/or more global states (e.g., feeling bad), as these specific emotions provide richer information about which behavior in one’s repertoire is more suited for dealing with a given affective situation
One way to think about this is to begin by asking, what are emotions for? Emotions provide instant and powerful information when making decisions. They have access to long-term experience as well as the internal state of the animal (think: HANGRY!). Famously, patients with mPFC damage are ‘overly-logical’ and, consequently, make very poor decisions; there’s just not enough information in the world to make Spock-like decisions all the time!
In a review we published recently (pdf), we discussed the possibility that emotions are a way of properly responding to information in the world. When you’re in a good mood, you’re more responsive to positive stimuli. Conversely, when you’re in a bad mood, you’re more responsive to negative stimuli. Therefore, if you want to respond to the world optimally, you’ll need the right mix of moods for the right environment: emodiversity.