We don’t. Burritos exist.

My thoughts were: At the mercy of their owner for one. Then a simpler obligate carnivore’s taste buds and brain reward system vs an easily bored omnivore with thumbs and unga fire.

Cats can be pretty different with food preference compared to each other. My two aren’t super picky. One is allergic to something in kibble so they both only eat wet food. I noticed above all that they vastly prefer paté pucks to a mince in gravy, no matter what flavour any of it is. Seems to leave them feeling fuller too afterwards. Priority: scent, mouth feel, and then taste is considered last is my observation.

There are lots of dogs and cats who crave variety in their diets, too. Like humans, it’s a behavioral thing rather than a nutritional necessity. My shepherd will simply stop eating regularly unless I vary her diet. I usually have three or so options I rotate through to keep her interested in eating. Lots of people add toppers and mix-ins when they have dogs like mine, but I find that only increases food rejection, as smart pups learn to hold out until we sweeten the deal enough.

I worked for a pet food manufacturer, and it amazed me what customers would do to try to entice their picky pets to eat. One guy was giving his dog lasagna, and he was shocked that his dog didn’t want to eat kibble anymore. Imagine that.

Cause we force them to

To add on to other peoples answers regarding the complete nutritional makeup of pet food; many animals can make a variety of the amino acids they need to survive with just a few inputs (like deer and cows eating only (mostly) plants), but some, especially predatory animals, cannot. They get those nutrients from the prey they eat, which in turn got them from the plants.

It essentially comes down to which enzymes any given organism can create, which ones their DNA codes for *or which microorganisms are allowed to exist within their system. Humans can’t make a bunch of these amino acids themselves. Many (maybe all of them, not that far into my class yet) of the reactions taking in place in any living organism are entirely reliant on enzymes to catalyze them; that is, without them these reactions would take millions of years to complete.

BTW there are appr. 37x10¹⁷ (3,700,000,000,000,000,000) reactions happening in your body every second. All of them (or at least a great majority of them) require enzymes to complete.

My current cats have Opinions (capital O) about what is or isn’t food. I tried giving them variety, at least in flavour. They don’t want it. The want one specific brand of fish-flavored wet food (in jelly, not gravy). They’ll eat some kinds of fish-flavored kibble if wet food isn’t available. Anything else, they have to be pretty desperate.

At least they both like the same stuff! But the lack of variety is 100% on them, not me.

(My previous cats would eat most things. These two are just weird.)

need a variety of food to survive?

It’s not true.

Boredom feels terrible while it lasts, but it doesn’t kill you. In the end, humans usually start to get creative after boredom.

Oh, and yes, some food industry has found out things and told you things… yes, they were creative :-)

You as a human could also live with the same food every day if it covered every dietary need. Especially if you depended on someone else to acquire it and had no choice.

There is an evolutionary push for a rich variety of nutrients obtained from a variety of sources, but the mechanism driving that daily “need” for variety is force of habit and desire for novelty. On top of that, some people are happy to eat nothing but junk and have very narrow tastes. How come?

Also, I can assure you, a lot of cats will periodically stop eating a certain brand or flavor and go through cycles. Does it mean the food isn’t really covering their needs or are they just bored of the same flavor every day? Hard to know, but I would argue your assumption about humans being too different from their pets when it comes to variety in their menu.