Taste Responsiveness to Food-Associated Acids in the Squirrel Monkey (Saimiri sciureus)

The taste responsiveness of six adult squirrel monkeys to five food-associated acids was assessed in two-bottle preference tests of brief duration (5 min). In experiment 1 the monkeys were given the choice between tap water and defined concentrations of citric acid, ascorbic acid, malic acid, acetic acid, or tannic acid dissolved in tap water. In experiment 2 the animals were given the choice between a 50 mM sucrose solution and defined concentrations of the same acids dissolved in a 50 mM sucrose solution. With both procedures Saimiri sciureus significantly discriminated concentrations as low as 10 mM ascorbic acid and acetic acid, 5 mM citric acid and malic acid, and 0.2 mM tannic acid from the alternative stimulus. The results showed: (1) that squirrel monkeys respond to the same range of acid concentrations as other nonhuman primate species tested so far, (2) that Saimiri sciureus detects food-associated acids at concentrations well below those present in most fruits, and (3) that the responsiveness of this New World primate to acidic tastants was largely unaffected by the addition of a sweet-tasting substance. The results support the assumption that squirrel monkeys may use sourness and/or astringency of food-associated acids as a criterion for food selection.