Why are cats such picky eaters when dogs seem willing to wolf down just about anything they encounter? It’s a question many pet parents likely ask themselves while coaxing their feline friend to swallow a pill or prying another slobbery piece of mulch from their puppy’s mouth.

There’s still a lot scientists don’t know about animal taste preferences. But, thanks to a small but growing body of research, researchers are starting to unravel some of the mysteries around our four-legged friends’ flavor fancies. Here’s what we know so far.

What can cats taste?

Accidentally drop a cupcake on the ground and your dog will probably scarf it down in one bite. Your cat, on the other hand, may turn up her nose. One possible reason for their differing behaviors? Cats can’t taste sweetness.

Since they couldn’t just ask cats directly, researchers figured this out by analyzing their DNA. But if cats can’t detect sweetness, what can they taste? Given cats’ meat-centric diet, scientists long suspected they could taste umami, the rich, savory, meaty flavor Japanese speakers describe as the "essence of deliciousness". And, recently, they found evidence to confirm this hunch.

To take the study a step further, they gave 25 felines the choice between a bowl of plain water and one that’d been spiked with molecules that provide umami flavor. As expected, the cats strongly preferred the umami water, and more specifically, water containing umami compounds present in tuna. That may help explain why felines love the saltwater fish so much.

Dogs, by contrast, can taste sweetness and umami. And both cats and dogs have bitter taste receptor genes, though cats have 12 (seven of which are functional) and dogs have 15. What remains unclear, however, is how the number of bitter receptor genes affects the animals’ actual perception of bitterness, researchers say.

You are (genetically) what you eat

The sense of taste helps animals evaluate potential food sources. Sweetness, for example, indicates a food is rich in carbohydrates, which are a good source of energy. Umami signals protein, while saltiness denotes sodium, an essential nutrient. Sourness is a bit more complicated, but scientists believe it may communicate acidity, which could be helpful for ingesting vitamin C or for determining if rotting fruit are actually safe to eat (since the “good” bacteria that makes them taste sour would kill off any “bad” bacteria during fermentation).

The evolutionary purposes of bitterness are also up for debate, though the long-held belief is that it may signify toxicity. The ability to detect these tastes shows up in animals’ DNA. Specific genes are responsible for producing different types of taste receptors on animals’ taste buds. Sometimes, these taste receptor genes randomly mutate. If the animal survives just fine with the mutation, they’ll pass that trait along to their offspring until, eventually, it becomes the norm.

Scientists think this is likely why carnivorous cats can’t taste sweetness, why bamboo-eating pandas can’t taste umami, and why some marine mammals that swallow their food whole, like dolphins and whales, have no functioning taste receptor genes at all. At some point in history, some of these species’ taste receptor genes stopped working properly and, because of their dietary needs, they simply stayed that way. "There’s a correlation between what you eat and what is reflected in your genome", researchers mentioned.

The taste differences between cats and dogs also make sense in the context of their diets. Cats are "obligate" carnivores, which means they can get all the nutrients they need from animal flesh. Dogs, on the other hand, are opportunistic feeders who take advantage of whatever food sources are available—whether meats, plants, or grains. "One reason why dogs may not be as fussy is because they are quite happy and able to eat a range of different foods", say researchers.

Their own "sensory" world

Pets perceive the world differently than we do. Understanding these differences could provide valuable insights not only for pet owners, but also for veterinarians, pharmaceutical companies, and pet-food manufacturers.

Leaning into the research could also lead to the development of supremely yummy foods and more palatable medicines for cats and dogs, though scientists say more work needs to be done to fully understand our pets.