2019-01-06 20:27:39
Anyone who has run a finger across the surface of a domestic cat’s tongue (running your finger across a lion’s tongue is more exciting, but much more dangerous), will have found that it is very rough. It is not for less, because the surface of the cat’s tongue is covered with what have been called filiform papillae, formed by keratin, that is, by the same protein that also forms nails and claws. These papillae create a surface of small, variegated spikes facing the back of the tongue.
Cats have inhabited the planet for eleven million years. By comparison, cats were domesticated in Southeast Asia only about ten thousand years ago, but today a domestic cat lives better than the king of the jungle ever did. The lucky kitty sleeps about fourteen hours a day and, of the ten that he spends awake, around two and a half are dedicated to grooming himself.
Grooming, however, is not a leisure activity, since in Nature it is necessary for the survival of felines. Combing the skin with its rough tongue allows it to eliminate parasites, such as fleas, loose hair, and evacuate excess heat. This hairstyle is important because the skin of cats has two layers of hair. The outer layer performs a protective function, while the inner layer, made of finer hair, serves to maintain body heat. If cats do not groom themselves properly, the hairs on the skin become tangled and matted, which can favor the formation of infectious foci.
Hollow papillae.
Studies carried out in the eighties of the last century concluded that the filiform papillae were like small conical spikes. Now, researchers at the Georgia Institute of Technology in Atlanta, USA have reanalyzed the tongue papillae of several felid species, including the cat, with more recent and powerful imaging technologies, and have found that the filiform papillae are not perfect cones, but are actually the tip of These cones are hollow and form a small container. This particularity allows the filiform papillae to be easily loaded with saliva at their upper end, saliva that will serve to moisten the skin and hair and facilitate combing.
However, while the above discoveries may be of interest to cat lovers, they also raise deep questions about felid evolution. Why, among other possibilities, has its evolution led to this type of language? Does this have to do with the type of skin they have also developed, which is different from that of other carnivores? Perhaps the type of skin and fur of felids is very effective in preventing blood from adhering to it by brushing with the tongue, which could serve as a culture medium for pathogenic bacteria. Perhaps brushing the fur with the tongue after hunting and eating is a behavior that has evolved as a way to avoid this possibility, thereby increasing the survival of clean cats over dirty ones. Infections are the main cause of weakness and disease in Nature, and weak animals, including weakened cats, often become easy prey.
We see once again that a simple discovery, apparently without much scientific importance, can raise serious questions that will require new and in-depth studies to answer them. This is one of the wonders of science that we live today: the answers always bring new questions, new stimuli to human curiosity.
Reference:
Alexis C. Noel and David L. Hu (2018). Cats use hollow papillae to wick saliva into fur. PNAS.
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Kilo of Science Volume I. Jorge Laborda
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