Why does your cat need to know bitterness?
After taking a bite of something bitter you might want to spit it out. And your cat might do the same.
But Fluffy might be expressing more than just being a picky eater.
Cats can taste bitterness too, says a new study.
In fact, domestic cats have at least , according to the paper published Wednesday in the journal PLOS ONE. (By comparison, humans have .)聽Taste receptors, proteins that trigger a signal when a substance encounters the receptor, are necessary for animals to experience taste.
The presence of functional bitter taste receptors in cats surprised scientists, because cats, being obligate carnivores, eat only meat. Perception of bitterness has long been thought to be linked with the consumption of plants.
鈥淲e don鈥檛 really know what bitter taste actually does, functionally speaking,鈥� study author Gary Beauchamp, emeritus director and president of the Monell Chemical Senses Center tells 海角大神 in an interview.聽
Previously, scientists thought the ability to taste bitterness was to protect animals from eating poisonous plants. Cats are unlikely to snack on plants, so the scientists expected no functional bitter taste receptors in the felines.
Dr. Beauchamp suggests a few explanations. Perhaps 鈥渢he prey of cats does include things that are not plants but may have bitter taste to them, such as invertebrates, spiders and stuff like that,鈥� he says. Or, maybe the taste receptors serve other protectional functions internally.聽
鈥淚t turns out these receptors are found throughout the body. They鈥檙e in the nose, they鈥檙e in the upper respiratory tract, they鈥檙e probably in the gut,鈥� says Beauchamp. That bolsters the idea that taste receptors could be involved in a more complex defensive or warning system.
When humans put a forkful in their mouth, they experience taste in a multi-sensory way. 鈥淲hen the general public uses the word 鈥榯aste鈥� it鈥檚 referring to the sensory experience of essentially anything you put in your mouth, chew up and swallow. But that is really made up of three different senses,鈥� Beauchamp explains.聽
First, there鈥檚 the sense of taste, which is the subject of this study. But the sense of smell is also involved, as the scent of a meal wafts into one's nose. The third is a sort of irritant experience, like the burn of hot peppers.聽
鈥淭hose things are all perceived as a single thing,鈥� says Beauchamp. But anatomically, taste is just the signal of important nutrients or poisonous compounds present in a substance.
There鈥檚 still a lot more to be learned about the function of taste receptors and their prevalence in different animals.聽
鈥淒ifferent species see the world and taste the world in different ways depending upon their ecology and their evolution,鈥� Beauchamp says.聽
Cats鈥� completely carnivorous diet is distinct from our own, so, he says, 鈥渨e鈥檙e trying to understand how their experience, their oral experience, is matched to their diet.鈥�
Cats may be like humans in that they find bitterness unpleasant, but previous research revealed that 聽鈥� something humans tend to crave.
鈥淥n the one hand we find they don鈥檛 like sweet things, which is unbelievable to a child 鈥� all kids love sweets,鈥� Beauchamp says, 鈥淏ut on the other hand, they are like the child in the sense that bitter things are very unpalatable and seem to be perhaps a signal of danger of some sort.鈥�
Flavor isn鈥檛 just about poison or danger. Taste appears to helps animals, including humans, get enough of nutrients. Sensing sweetness, for example, is a way that the body identifies sugars.
鈥淚n some sense, the taste system is the last gateway on the biggest decision intrinsically that any animal makes, including you and me, any time in their lives,鈥� Beauchamp says. 鈥淭hat is, am I going to take this thing and put it into my body or am I going to reject it?鈥�
