It all sounds a bit insane: people who like sweet foods are someone just generally nicer than people who don't. It sounds like the latest example of dubious evolutionary psychology, but it's actually about how language subtly shapes our behavior.
A team of researchers from North Dakota State, Gettysburg College, and Saint Xavier University designed a series of five experiments to see how taste preferences related to behavior. One experiment showed participants that ate a sweet food like chocolate were more likely to volunteer to help somebody than those who had eaten a non-sweet food like a cracker. Another study revealed how people view the taste preferences of others. It turns out people tend to think those with a sweet tooth are more agreeable and helpful than others, and less likely to be neurotic or extroverted.
There are a bunch of ways one could attempt to explain this result. You might apply an evolutionary perspective to all this and imagine that, in the early days of humanity, those who particularly liked sweet foods were good at foraging for fruit. Gathering food is a cooperative activity, and those who found the most fruit would by extension be seen as particularly giving and helpful by the rest of the group. Of course, that's all completely bonkers, but it wouldn't be the most ridiculous thing I've heard lately.
But the researchers took a different, rather more interesting tack. Their hypothesis is that language encodes certain metaphors that link otherwise unrelated areas of our experience, and that over time how we think of one can affect how we view the other. Gettysburg professor Dr. Brian Meier explains:
"Taste is something we experience every day. Our research examined whether metaphors that link taste preferences with pro-social experiences (e.g., "she's a sweetheart") can be used to shed light on actual personality traits and behavior.
"It is striking that helpful and friendly people are considered ‘sweet' because taste would seem to have little in common with personality or behavior. Yet, recent psychological theories of embodied metaphor led us to hypothesize that seemingly innocuous metaphors can be used to derive novel insights about personality and behavior. Importantly, our taste studies controlled for positive mood so the effects we found are not due to the happy or rewarding feeling one may have after eating a sweet food."
That last bit is an important caveat - it is possible that the effect the researchers observed is a physiological reaction to sweet foods, not a psychological one. But assuming they did correctly control for the rewarding feeling that sweet foods can provide, then these findings do seem to support the idea that a preference for sweet foods inclines people to generally act sweetly. North Dakota State's Dr. Michael D. Robinson adds:
"Our results suggest there is a real link between sweet tastes and pro-social behavior. Such findings reveal that metaphors can lead to unique and provocative predictions about people's behaviors and personality traits."
Admittedly, this is all still a pretty out there idea, and it's possible this metaphors hypothesis is no closer to the truth than my ancient fruit foraging proposal. But there is some good news - it's actually possible to test this hypothesis further. The researchers point out that these results are specific to English, in which "sweetness" has very clear meanings in terms of both taste and disposition.
But such links won't exist as strongly in other languages, and it could be completely absent in others. Examining this effect across cultures could help reveal whether particularly strong embedded metaphors really can shape people's behavior...or whether this all has the distinct odor of crap science on it after all.