I tried to find an answer by googling, but all (and I mean ALL) search results deal with how palatal rugae can be used to identify corpses, or to help dentists in assessing this and that treatment. But I can’t find any link that discusses why humans (and animals) have them in the first place.
My guess is that they help us hold food in place while we’re chewing. I have noticed that cats and dogs have massive rugae, while humans only have tiny ones. Maybe they function as a sort of grippers, preventing prey from escaping?
Or do they house any glands or receptors?
“Rugae are only evident when an organ or tissue is deflated or relaxed. For example, rugae are evident within the stomach when it is deflated. However, when the stomach distends, the rugae unfold to allow for the increase in volume. On the other hand, plicae remain folded regardless of distension as is evident within the plicae of the small intestine walls.”
“On the anterior portion of the roof of the hard palate are the transevese palatine folds (rugae) which are the irregular ridges in the mucous membrane that help facilitate the movement of food backwards towards the pharynx.”