Evolution May Explain Why Cats are Fussy Eaters

If you own a cat, you’re probably already well aware of what fussy eaters they can be. One day they love chicken, the next they’ll only eat tuna. Today they like this brand, tomorrow they’ll want that one. We’re all entitled to our preferences, of course, but that doesn’t make watching your kitty turn their back on food you’ve just spent a small fortune on any less frustrating. For years, we’ve written off their fussiness as a personality issue. But as it turns out, there may be more to it than we thought. Recent studies have suggested that evolution might be at the route of your cat’s fussy eating. They’re not just being difficult – they were born that way. If the research holds up, it would certainly explain a few things. Even better, it could help prompt pet food manufacturers to make their products more appealing to cats.

The Research

Cats aren’t big on green foods. If you’ve ever seen them throw up after munching on grass, you’ll know what we mean. Until now, we didn’t have too much of an explanation for their response. But after a team of researchers decided to put a few common theories about carnivorous eating habits to the test, we might just have found the reason. As iflscience.com writes, the ability to detect bitterness developed as a defense mechanism against the harmful toxins found in certain plants and fruits. The ability to taste sweetness developed as a way of guiding animals toward energy-dense food choices. As meat-loving cats have lost the ability to detect sweet substances over time (presumably because their flesh-based diet gives them no reason to detect plant-based sugars), we’ve long believed they’ve also lost their ability to detect bitterness.

Considering plants form no part of their diet, there’s no real reason for cats to be able to detect bitterness anymore. By now, evolution should have tweaked their taste buds to suit their dietary needs. It would therefore be expected that they’ve either lost their functional bitter receptors or that those bitter receptors have become so riddled with mutations to have lost all efficacy. Which kind of begs the question of why they turn their nose up at certain foods and not others. Determined to prove once and for all if cats can still detect bitter tastes or not, a team of researchers consisting of Michelle Sandau, Jason Goodman, Anu Thomas, Joseph Rucker, and Nancy Rawson set out to investigate. The resulting study, ‘Functional Analyses of Bitter Taste Receptors in Domestic Cats (Felis catus)’, published in BMC Neuroscience, proved illuminating.

The Taste Test

To find out if cats can detect bitterness (and hopefully find some explanation for why if so) the scientists began their research with a taste test. As pawmanefin.com highlights, the team used 25 commercially available compounds (including 8 which humans find bitter) to simulate bitter taste stimuli. They found that cats have 12 intact as2r receptor genes (i.e., receptors that allow them to detect bitterness). Some of the receptors could detect a broad range of tastes, others were narrow in their range, while others were in-between.

The Conclusions

As the researchers’ study points out, if the belief that “bitter receptor function is strongly influenced by whether a species consumes plants” were true, it would suggest that obligate carnivores would have few, if any, functional bitter receptors. In the same way that cats have lost their ability to taste sweet because they’ve got no use for it, they should also have lost their ability to detect bitter compounds. But the research suggests the opposite. Cats don’t have fewer bitter receptors than their omnivorous counterparts, and those receptors are still functioning despite plants forming no real part of their diet.

What it Means

The research shows that cats have retained their ability to detect bitter tastes. But why? The carnivorous basis of their diets results in such minimal exposure to plant toxins (certainly when compared to their vegetarian counterparts), it begs the question of why evolution hasn’t yet tweaked their taste buds. Sure, they might decide to have the occasional chew on something they shouldn’t, but for the researchers at least, this wouldn’t be enough to explain why they still have such a huge arsenal of taste receptors at their disposal. Whatever the reason for their continued ability to detect bitterness, there has to be more to it than just taste. In humans, bitter taste receptors can be found in both the heart and the lungs, where they’re believed to function as infection-detectors. Although it’s not yet known if this could also apply to cats, the researchers posited a number of other interesting theories that could help explain why cats retain functional bitter receptors. These included:

While cats are carnivorous, even committed meat-eaters ingest a small amount of plant material via the stomach contents of their prey. While plant toxins are the biggest source of bitter foodstuffs in an animal’s diet, other non-plant components such as bile acids in prey could be equally hazardous if consumed. The bitter receptors on a cat’s tongue allow them to detect these potential toxins, helping them avoid harmful foods and potential poisoning.

The Pickiest Eater

While the research concludes that feline taste receptors are still in full working order, it doesn’t necessarily help us figure out why cats are quite as picky as they are. But earlier research into the subject just might. Previous studies have suggested that feline taste receptors are even more sensitive to bitter compounds than human taste receptors. If that’s the case, it may explain why dogs seem to chow down on anything you give them, while cats will walk away from anything that doesn’t appeal.

The Future for Food

Taken in isolation, the study’s not particularly helpful to cat owners. It may explain why their cat turns their nose up at certain foods, but it doesn’t necessarily help give a solution. But think about it. Now we understand their response to certain foods, we can start to do something about it. Up until now, many foods and medicines have contained bitter-tasting ingredients, presumedly under the assumption that cats aren’t able to detect them. But now the research has shown they can, it may help prompt manufacturers to look into alternatives, resulting in a happier cat and a happier cat owner.

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