"The mouth is a magnificently sensitive somatosensory organ (sensing stimuli from the skin and internal organs), arguably the most sensitive in the body," said Paul Breslin of Rutgers University and the Monell Chemical Senses Center.

"The way foods make our mouths feel has a great deal to do with what foods we choose to eat," added Breslin, according to a Rutgers and Monell statement.

It might explain the appeal of salad dressings, with their characteristic acids and oils, for example. Think also of the pink folds of ginger on the sides of sushi plates or the soda with burgers and fries. Researchers knew that astringent wines feel rough and dry in the mouth.

Fats, on the other hand, are slippery. There was the notion that the two might oppose each other, but it was not quite clear how that might really work.

Breslin, Catherine Peyrot des Gachons and colleagues now show that weakly astringent brews -- in this case containing grape seed extract, a green tea ingredient, and aluminum sulfate -- build in perceived astringency with repeated sipping.

When paired with dried meat, those astringent beverages indeed counter the slippery sensation that goes with fattiness.

This natural tendency for seeking balance in the mouth might have benefits for maintaining a diversity of foods in a diet.

"The opposition between fatty and astringent sensations allows us to eat fatty foods more easily if we also ingest astringents with them," Breslin said.

As an aside, Breslin adds, fresh seeds and nuts could have a certain sort of appeal.

"These foods come both with their own fats and astringents in one package, so they may be self-balancing."