Why Does Sour Food Make Us Cringe? (asked by Anonymous)
Turns out, not many people have directly looked at this – the scientific literature has relatively little to say on the topic of cringing at sour food. However, what it does say is this: the cringing facial expressions are part of a general ‘disgust’ response that we make towards unpleasant smells and tastes. Some aspects of the face we pull when we eat sour sweets or a particularly tart tangerine are also produced when we smell off milk or bite into a rotten apple. The disgust response is designed to stop us from eating poisonous or rotten food, and to communicate with others around us that the food is bad. It probably formed a key part of social foraging, enabling early humans to avoid bad food and share information within their social group.
But why do we respond this way to sour food? Scientists believe that sourness may have, during human evolution, signified poisonous foods that should be avoided. Why we now have a love-hate relationship with sour food, is another matter entirely. In part, the explanation is one of nature and nurture. Innate aversions to poisonous foods, for example, would have been an evolutionary benefit to our ancestors, but learned aversions offer greater flexibility and would have helped early humans adapt to their current environment. So, although there are some things we find inherently disgusting, a great deal of our food preferences are based on learned experience. Sour is not a perfect indicator that food is inedible, and we can learn to appreciate it if it is associated with positive experiences in childhood (thanks, Haribo!). Children tend to be born with a distaste for bitter and sour food, but these aversions can be overcome with age (although some suggest that adults become more tolerant to these tastes simply because the sensitivity of our tastebuds decreases with age).
Science has some other interesting things to say about our relationship with sour food, though. A study published in 2007 showed that our ability to perceive sourness in food has a strong genetic component, explaining about 53% of variation between people in their ability to detect sour tastes. One Danish study also found sex differences in the perception of sour foods, with girls better able to identify sour flavours, but boys more likely to enjoy sour foods. They also found that these abilities change with age – we become better at perceiving sour taste during our teenage years. Ancient humans would have likely begun foraging around this age, so improved sensitivity to potentially toxic food would be a big advantage!