It seems that many flavor and food preferences can be explained in the context of regulating feeding behavior. Generally, organisms tend to enjoy those foods which are optimal for them to feed on and provide the best nutrition. There are well-known exceptions to this, such as:
- Artificial chemicals (eg. the supposedly sweet-tasting but deadly polyethylene glycol) which are very rare in nature, thus there was no opportunity for an appropriate taste perception to evolve
- Nutrients which are desirable in moderation but dangerous in excess (eg. sugar), but have only become readily available recently thanks to technology (thus once again moderated consumption has not had opportunity to evolve)
But humans in particular also seem to enjoy consuming a large variety of foods that one would expect to be unpalatable or mildly harmful. For instance various peppers, spices, hot sauces, wasabi, mustard and so forth, don't appear to provide much of a nutritional benefit. Indeed their chief property of interest, the spicy flavor, is a defense mechanism: The plant attempts to make itself unpalatable or toxic to deter predation. Why is it then that this very defense mechanism has ironically become prized as a food ingredient by humans, to such an extent that wars have been fought over access to spices? And why is it that humans do not consider (for instance) pure, fresh, raw meat to be more delicious than meat with seasoning or condiments?
There has been a similar question (see comments) on here but that has also not attracted a good answer. I think this exemplifies the enduring interest in the subject and as such I'd like to keep this question open to stimulate a better response from more recent visitors.