Most cat caregivers have come to accept that cats just aren’t very adventurous when it comes to their food. But why?
In plant-eating animals, bitter taste receptors (taste buds) alert the eater that the plant being eaten may contain toxins (which taste bitter), thus limiting consumption of potentially toxic plants. Smart.
Another smart thing that nature does is getting rid of stuff it’s not using. For instance: cats evolved eating meat, which contains more than enough taurine (an essential amino acid for cats) to meet their needs. While their distant ancestors possessed the enzymes needed to make taurine from other amino acids, the cat never used them, as it got all the taurine it needed from its diet. Maintaining working enzymes takes a fair amount of energy in the body, and if an enzyme isn’t being used, there’s a survival advantage to the individual who manages to get rid of it (by either deleting or not expressing the genes for that enzyme).
So, with that in mind, it makes sense that an animal that evolved as a carnivore would have lost those bitter taste receptors that are protective for plant eaters.
A group of researchers at the Monell Chemical Senses Center in Philadelphia recently published research that aimed to determine if that was the case.
In this study, the group isolated taste receptor genes from cats, and made cells in culture (petri dishes) express these genes. The experiment was designed so that when the cells were exposed to a compound that is bitter (according to cat taste receptors), a detectable reaction would occur.
If it was true that cats had lost the ability to taste bitter compounds since they no longer needed to be able to tell which plants were toxic and which plants are good to eat, then the cells in culture wouldn’t react to any of the substances tested. But, that’s not what happened. The researchers found that the cat taste receptors reacted to a wide variety of bitter compounds.
Now we know that cats can and do taste bitter compounds in their food, which gives some explanation for why cats can be so finicky with food. Rather than assuming that evolution just didn’t happen here, or hasn’t caught up yet, it seems that cats are using these receptors for something other than what we’d thought. Exactly what that is, we don’t yet know.
Typical cats. Keeping us guessing.