Photo: Cayambe · CC BY-SA 3.0
Sweet
Cats cannot taste sweetness.
4 min readLast updated
The short answer
Yes. Cats lack a working sweet taste receptor because a key gene, Tas1r2, is broken. Lions, tigers and other cats share this trait, likely because they evolved as strict meat eaters.
Why it's true
Sweet taste in mammals depends on a receptor made of two proteins, coded by the genes Tas1r2 and Tas1r3. In cats, Tas1r2 is a pseudogene, meaning it has mutations that stop it from making a working protein. Without it, cats cannot detect sugars as sweet.
A 2005 study by scientists at the Monell Chemical Senses Center showed this genetic change in house cats, tigers and cheetahs. Behaviour tests matched: cats show no preference for sugar water. Since cats eat almost entirely meat, which contains little sugar, losing the sweet sense did them no harm.
Cats are sensitive to other tastes, including bitterness, and may even taste certain amino acids common in meat.
By the numbers
Tas1r2
Broken sweet receptor gene
2005
Monell study published
~470
Taste buds in a cat, compared with thousands in humans
Obligate carnivore
Cat dietary category
How we know
Pet owners had long noticed that cats ignored sweet treats, but the reason was unclear. Xia Li, Joseph Brand and colleagues at Monell analysed the cat Tas1r2 gene and found it was missing a section and filled with stop signals, preventing a working receptor.
Later work found similar sweet receptor losses in other carnivores, including sea lions, otters and some hyenas, though not all. Dogs, which eat a more varied diet, can still taste sweetness. The pattern shows how senses evolve to match diets, keeping what helps and losing what does not.
Evolution switching off a sense
When a sense is no longer useful, mutations that break it may not harm an animal, so they can spread through a population.
Over time, genes can become pseudogenes, leaving traces of a lost ability that scientists can read in DNA.
Worth remembering
- Cats cannot taste sweetness.
- The Tas1r2 gene for sweet taste is broken in cats.
- Big cats share the same missing sense.
In context
Taste helps animals find nutrients and avoid poisons. Sweetness signals sugars and energy, bitterness often signals toxins, and umami signals proteins. Animals that eat different foods tend to have different taste abilities.
Giant pandas, which eat mostly bamboo, have lost their working umami receptor, the opposite pattern from cats. Many whales and dolphins have lost several tastes entirely, perhaps because they swallow prey whole.
Cats have strong senses elsewhere. Their sense of smell is far keener than ours, and smell plays a big role in what food they accept.
A closer look
A picky eater's tongue
Cats have far fewer taste buds than humans, around 470 compared with thousands.
Their tongues are covered with backward facing spines, which help groom fur and scrape meat.
Bitter sensitivity
Cats have several bitter taste receptors and can detect bitter compounds.
This may help them avoid toxic substances and explains fussy reactions to some medicines.
Why cats like meat
Cats need nutrients found mostly in animal tissue, such as taurine.
Their bodies are adapted to a high protein diet, which is why they are called obligate carnivores.
Related facts
More about the cat family cheetah claws only partly retract.
Compare with human taste humans taste at least five qualities.
Smell matters even more for cats smell is part of flavour.
Diet shapes animals in surprising ways poison frogs get toxins from food.
Key terms
- Taste receptor
- A protein on taste cells that detects specific chemicals in food.
- Pseudogene
- A gene that no longer works because of mutations.
- Obligate carnivore
- An animal that must eat meat to get essential nutrients.
Myth vs reality
Myth
Cats like milk and sweets because of the taste.
Reality
Cats cannot taste sweetness. Many adult cats are also lactose intolerant.
People also ask
Can cats taste sweet things?
No. A gene needed for the sweet taste receptor is broken in cats, so they cannot detect sweetness.
Do big cats taste sweetness?
No. Tigers and cheetahs share the same broken gene, according to the 2005 study.
Can dogs taste sweet?
Yes. Dogs have working sweet receptors, which fits their more varied diet.
Why might cats eat sweet foods?
They may be attracted by fat, protein or texture in foods like ice cream, not the sweetness.
Should cats drink milk?
Many adult cats are lactose intolerant, so milk can upset their stomachs. Water is the best drink for cats.
