Pseudogenization of a sweet-receptor gene accounts for cats' indifference to sugar

This landmark genetic study explained the long-noted fact that cats show little interest in sweet foods. The researchers found that cats carry a defective, non-functional version of Tas1r2, one of the two genes needed to build the mammalian sweet-taste receptor. Because Tas1r2 has become a pseudogene riddled with disabling mutations, cats cannot assemble a working sweet receptor and are effectively blind to sugary tastes. The authors documented the inactivating mutations and connected them to the cat's behavioral indifference to sweetness, framing the loss as consistent with an obligate carnivore that gains little from detecting sugars. The finding became a textbook example of how diet and evolution shape sensory genetics, showing that a strict meat-eating lifestyle can lead to the loss of a taste modality. It elegantly linked a single pseudogene to a distinctive feature of feline feeding behavior.