Why Your Pet Cat is a Picky Eater: The Evolution of Carnivorous Felines

Why is your cat such a picky eater? Scientists may have found out the reason. It turns out that cats have at least seven functional bitter taste receptors, which questions the common hypothesis that bitter taste developed primarily to protect animals from ingesting poisonous plant compounds.

"Alternate physiological roles for bitter receptors may be an important driving force molding bitter receptor number and function," said Gary Beauchamp, one of the researchers, in a news release. "For example, recent Monell-related findings show that bitter receptors also are involved in protecting us against internal toxins, including bacteria related to respiratory diseases."

Unlike sweet tastes, which just have one or two different receptor types, the number of functional bitter taste receptor types varies greatly across species. If bitter detected evolved to detect plant toxins, there would, in theory, be fewer functional bitter receptors in strictly carnivorous animals like cats.

In this latest study, the researchers examined DNA from domestic cats and identified 12 different genes for cat bitter receptors. They then evaluated whether these genes encode functional bitter receptors; they incorporated the gene sequence of each receptor into cultured cells and then probed the cells to determine if they were activated by one or more of 25 different bitter-tasting chemicals. In the end, the researchers confirmed that at least seven of the 12 identified cat bitter receptor genes are functional.

"Cats are known as picky eaters," said Peihua Jiang, one of the researchers. "Now that we know that they can taste different bitters, our work may lead to better formulations of cat food that eliminate the bitter off-taste associated with certain flavors and nutrients."

The findings reveal not only that bitter tastes are not associated with plant eaters, but also why your cat may turn up its nose at its daily bowl of food.

The findings are published in the journal PLOS One.

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