"... Omnivorous animals are faced with a dilemma, or a paradox. One the one hand they are equipped to try new food sources and have a vast range of choices, which enhances their chance of survival; on the other, any strange food is potentially harmful and may cause discomfort, even death. The omnivore's capacity for eating nearly everything, then, is tempered by an innate distrust of novelty.
...
Culinary tradition is a guarantee of safety, and usually of nutritional wisdom: if it worked for your parents, it will work for you.
Cuisines are also given to characteristic flavorings, which are most often their most distinctive aspect, and, which have little, if any, nutritional significance... These flavorings are usually carefully maintained among immigrant groups whose normal staple foods may be unavailable in their new home, and suggests an analogy to the well-known habit of animals of 'marking' their territories with their own scents. Strong distinctive flavors mark our food as familiar and so acceptable, and may help ease the introduction of new staple foods into the cuisine. And, on the other hand, the shared preference for certain flavorings can help reinforce a sense of social solidarity, a feeling of community. The popular interest in exploring novel, exotic cuisines, so evident in the current variety of restaurants and cookbooks, is a development only of the least three or four decades. "
On the topic of why we eat spices (see Darwinian Gastronomy earlier) we can rely on Harold Mcgee's 'On food and Cooking' to provide the extremely sensible argument above. It's based on research done by psychologist Paul Rozin. It gives a complete new meaning to the notion of edible geographies. One word though: this is copied from my old edition of the book, not the updated one in which I have not been able to find it.
'Darwinian Gastronomy: why we use spices' (1999, PDF-link) by Sherman and Billing is a nice and early example of an attempt to use statistical analysis of cookbooks to reveal deeper patterns about what we eat and why. The paper theorizes that there is an evolutionary benefit to eating spices: "by cleansing food of pathogens before consumption, spice users
contribute to the health, longevity and fitness of themselves, their
families and their guests." There is more disease in the tropics and this is also where most spices are added to food, or so the paper seems to argues. Personally I think the argument runs the risk of putting the horse behind the carriage. Spices predominately grow in tropical areas and it makes sense to expect that this is where they eat them most.
There are some very nice graphs showing spice-use in 36 countries and I can easily appreciate how much data (93 cookbooks) went into making them. But we are never told what those books were. How can someone who knows about these things ever make a judgement on how soundly food traditions/cuisines are represented? A cookbook is not a neutral source, but a vehicle of someone's dietary ideology. Something advertised as traditional may be less than a week old, something advertised as national may be produced by a radical fringe. What and where is the baseline? The paper, in its conclusion, recommends cookbooks "from different eras" as "a written record of our coevolutionary races against foodborne diseases." This I seriously doubt: the history of cookbooks is not old enough to pick up deep evolutionary changes. If we do eat spice as an antidote to unclean food we, in the West, could do without them, our ever growing love for spicy food shows the reverse.
A related paper explains why "vegetable recipes are less spicy" (PDF-link) from which we learn a debatable assumption made in the other paper: it treats fish as a meat.
