Field-testing olfactory ability to understand human olfactory ecology

Abstract

ObjectivesWe know little about human olfactory ability in natural settings because current knowledge derives from lab-based studies using non-representative samples of convenience. The primary objective was to use a validated lab tool, the five-item odor identification test, to assess variation in olfactory ability in different environments. MethodsUsing the five-item test, we conducted two repeated measures experiments that assessed participant ability to correctly identify an odor source in different odor environments. We also examined consistency in odor labelling due to documented potential bias from idiosyncrasies in odor terms. ResultsWe found no variation in olfactory ability due to environment, but this may be due to methodological biases. First, subjective bias results from idiosyncratic differences in participant labelling and researcher coding of answer correctness. Second, better ability to learn odors may provide an advantage to women. Third, reducing positive female learning bias by analyzing consistency in response (regardless of correct odor source identification) fails to assess functional olfactory ability. Functional olfactory ability (naming correct odor source) is significantly better in females, especially in food-rich odor environments. ConclusionsEnvironment was not a significant factor in olfactory ability in this study but that result may be confounded by methodological biases. We not recommend odor identification as a field tool. Functional olfactory ability exhibits a sex-based pattern but consistency in recognizing the same odor does not. Food-rich odors may enhance olfactory ability in females. We discuss evolutionary and ecological implications of superior female functional olfactory ability relative to food foraging activity.