If you think about it, for the past hundreds of thousands of years we’ve been regionally locked in our areas so variety is a loose term.

Wildcats (tigers, lions, bobcats, etc) will take down a prey animal. We think they just eat the muscle. In reality, they often go for the stomach of the herbivore they just brought down to get the vegetable matter there. Then they eat other internal organs (liver, spleen, kidneys) so they aren’t just eating muscle.

For our pets, well, we all know they don’t eat the same thing every day. Firstly, the the thing they do eat every day, pet food, has various nutrients included so it’s a balanced meal for them. Secondly, we give them treats which may or may not be beneficial.

As for we humans wanting variety, it’s exactly that. We want but don’t need as much variety as we get. We enjoy the different flavors even if the items containing those flavors aren’t exactly good for us (twinkies, 8 year scotch, etc). Our pets and wild carnivores don’t get the opportunity to try these other flavors (well, our pets get some opportunity but not to the extent we have granted ourselves).

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.)

Animal food is usually balanced to contain all the nutriens the animal needs, or most.

Ofc if it’s proper

We do not “need” a variety of food. We eat it because we can afford it and it makes us healthier and happier.

Daily reminder that pet food is a more recent industry and before it existed pets mostly ate table scraps.

Kongbap says nah, it’s all you need to survive.

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.

Cause we force them to

Not sure that’s a universal thing with cats. Unless she’s really hungry, the current feline resident of my household most definitely will turn her nose up at a dish if it’s the same as she was fed in the last meal.

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.

We don’t

Cats and similar animals are adapted to specific environmental niches, but humans are generalists. One of the drawbacks of being generalists is that we’re not specialized enough to fully subsist on any single food source.

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.

I’m a living proof that you can eat the same thing every day for decades and be just fine.