Cats Cannot Taste Sweetness

Dogs will demolish a cake given the chance. Cats, offered the same cake, take a polite interest and then wander off, and for years this was filed under cats being cats. The real reason is written in the genome.

A sweet taste receptor is built from two proteins working as a pair. In cats, the gene for one of them carries a deletion — a chunk of missing letters that stops the protein ever being made. The receptor cannot form. It is broken in domestic cats, and in tigers, lions and cheetahs too, which means the fault is ancient and shared right across the family.

It makes evolutionary sense. A pure meat-eater has little use for a detector tuned to ripe fruit, and a gene that nothing depends on decays quietly over the generations. What is left is a palate built almost entirely around meat: cats are unusually sensitive to the compounds in protein and fat, and to bitterness, which is a useful warning system.

So when your cat sits on the table staring at the ice cream, it is not the sugar. It is the cream, the fat, the smell of something rich, and quite possibly the simple fact that the ice cream is yours and the table is theirs.