You're going to have to tell us what the characteristics of this species are.

@KEY_ABRADE nope, the question is not about why creature X prefers this food, but about what factors decide the food preferences of creatures in general.

@KEY_ABRADE it's not different than asking what factors contribute to animals evolving 4 legs over 2 legs...actually it's the same exact question but with food and taste instead of legs.

It still depends on the creature. Animals eat what their biology is optimized for. Humans drink what's technically poison - alcohol - not because our biology is optimized for it, but because we like it (and it's addictive). The factors depend on the creature.

@KEY_ABRADE You are not entirely correct. Human bodies are adapted for processing ethanol. We even have special enzymes for it (something that we do not have for a vast number of other substances). It is also worth mentioning that some apes and monkeys leave fruits to ferment naturally and consume them as a source of alcohol. It would also be beneficial if you could respect the OP and their interpretation of their own query. While there are factors important for each individual species, there are general rules applicable to all species. The OP is asking for the latter.

@Otkin: I for one would be curious to learn about those rules applicable to all species. Remember that all species include detritivorous worms, snails, bees, coprophagous beetles, phytophagous fish, carcass-eating vultures and hyenas, cows, hypercarnivorous cats, and humans.

@Otkin It looks like the topic is quite too wide to get a lot of answers, though... Pushing up to the extremes on Earth, what are the common points in food preference between some medusae and I don't know, dogs or hamsters? How could we reliably relate those preferences with our own perception? To make this even harder, told as it is we need to check plant-based and non-carbon based creatures, too. I'd advise to explicitly narrow down to carbon-based, earth-related animals (ie ones we would commonly say they're animals, monsters or chimeras). That'd be more answerable, even if still not ideal.

@Tortliena assuming non carbon life is indeed possible and not just something related to the #magic tag, assuming creatures without a brain can feel taste, assuming creature that do not eat can feel taste. Plus it's not like I asked what type of proteins would the various species prefer but what factors determine food preference. Why is it ok to ask about general diets in the sense of herbivores vs carnivores but not ok to ask about general diets in the sense of taste? It's not like taste is an opinion or something philosofical, it's just chems.

This question seems more like a potential type of question rather than a single answerable question. I'd advise dividing this multiple questions about the specific species you'll be using

@SteroidSandwich Touché! You don't specify which kind of creature at all, so by default answerers could include conceptualized ones :). To be honest, I actually thought you wanted to know about "acceptable diets" instead of "I like this or I like that". The prefered taste/flavor is even more different among species than diets. I mean, it's an issue even among humans x)! And that's not taking into account differences in perception. There probably won't be even a single valid answer this way, so need more hocus-focus for me.

@AlexP One fundamental rule will be the preference for foods available in the habitat. I am not sure if other rules exist since I am not a biologist. Perhaps, evolutionary biology has an answer to this question. Please also consider that an answer that there are no rules and everything is a coincidence is a proper answer as long as it is supported by facts and research.

@Tortliena I think that this is a very specific question that requires expertise in biology and evolution. It is a theoretical question dealing with the evolution of species in general, not any specific one. It is also reasonable to assume that if some general rules exist they will be applicable to all life if our understanding of evolutionary processes is correct.

@Tortliena I mean there's a question about the creatio of the universe and galaxies and all the known factors that contribute to the speed of the process...not closed. It was asked by a moderator in fact.

@Otkin: "One fundamental rule will be the preference for foods available in the habitat": Citation needed. I for one cannot even imagine how such a preference would appear and what would be it be good for. Foods which are not available in the habitat are not available in the habitat, and thus they are not comparable to foods available in the habitat. (And I'm sure that the abundance of tuna in the Libyan desert is not the reason why cats like fish.)

@Otkin That's a wild guess, but I doubt there's a specialist in evolution of all animal life. There are reasonably specialists in the evolution of specific sets of animals (mammals, insects, ...), which will all suggest their own theories genuinely based on what they know. So my question is genuinely this : Should we pick one of them and extrapolate to all life, even if we don't know enough about them or their perception (in real world or conceptualized ones)? This is all supposing we (the animals) all have the chance to choose what we like or dislike, or that we all have preferences.

@SteroidSandwich Watch out, being a moderator doesn't prove anything nor should give more rights to think a question have its place there. I couldn't find the question... in question x), but the difference here is that you get one model you play with. In this case, we would have to take into account easily more than hundreds of thousand of species. Even if you regroup them into categories, you still get a lot you need to find common traits and I bet there's at least more than thousands that wouldn't comply to any answer.

I voted to leave this open in the first place as it's perfectly answerable as-is in my view. Fairly astonished no-one has attempted an answer yet, I may have a try later if it gets opened again.

@AlexP Can you imagine a preference for food that is not available in the habitat? Please, do not limit your imagination to your favourite cat. Think from an evolutionary perspective.

@Otkin: Most humans like pork. Pigs don't live in the African savannah. From an evolutionary perspective, anything can happen when a species expands outside its original habitat, or when a potential prey species comes in, and new food becomes available. Natural evolution is not set to look into the future and somehow forecast what foods which are not currently available should be prophetically be found tasty or repugnant.

@Otkin Yep, there is :). However, the problem lies not in the theory, but the fact that any answer is a bit like answering to the question "what would be the preferred method of alien locomotion?" with "Legs!" or "Fins!". If you followed the evolution theory, they would simply say "it depends!". It's just the same as well when calling for "high-nutritious food" (why would cows eat grass then?) or any answers : "It just depends!". [...]

[...] Yet, it's not the killing point for me. It's that the asker project our vision ("we like", "we don't like") to animals we don't even know if they can have the luxury of "preferences". Just like how people project their culture over others, as you know it ;p. This adds some unnecessary blur to it. It's something you also made, too, confusing what you can eat and what you're willing to eat. It's what made me reached a too "high-extrapolation, simplification and generalization" line to close this question.

@Tortliena Please read the query carefully. The OP asks 'So what defines what type of foods different species prefer?'. The question is not about specific preferences, but about the rules that lead to specific preferences. In other words, it is a question about what it depends on, not anything else.

@AlexP Have you tried to see it from the process perspective? What factors influence taste preferences? What factors create aversion? Why some species are carnivorous, some herbivorous, and some are omnivorous? Is it possible to develop preferences for substances that are not present in the habitat where most of the evolutionary development happens? If yes, what factors contribute to this? Why do people like pork and don't like mud?

@Otkin Then... "It just depends!". Is that a satisfactory answer? It's not for me, and a sign it's too broad.

@Tortliena I honestly do not understand how do you come to a conclusion that 'it just depends!' is a proper answer. Would you consider 'rules exist' a proper answer to a question about WB.SE VTC rules? Would you consider a question about WB.SE VTC rules to be too broad?

Let us continue this discussion in chat.