How Biology perceives Chemistry: Smells as Environmental Kinds
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How Biology perceives Chemistry:
Smells as Environmental Kinds
Ann-Sophie Barwich
(Indiana University Bloomington)
Friday November 26, 2021 1:00-3:30pm EST
This is a virtual / on-line event.
What creates that distinct fruity odor of peach instead of mango or strawberry? I argue that the answer is not a correspondence relation linking a set of microstructural features with odor categories but demands a computational understanding of odor images. Orthodox explanations of odor perception in both science and philosophy have centered on structure-odor relations (SORs) to determine which particular parameters of a molecule may constitute its odor quality. To date, no such account has succeeded in delivering a straightforward mapping of the chemical stimulus with human sensory responses. SORs are notoriously riddled with irregularities, so much so that the exceptions constitute the rule. The inherent irregularity of odor chemistry is more than a big data challenge in tackling the molecular complexity of the stimulus. Drawing on recent studies in neurobiology and psychophysics, I show that understanding what constitutes the identification of odor quality, including its sensory classification into perceptual categories (such as musk or apple), requires a systems theoretical approach. Specifically, I advance an explanation of odors as ecological kinds. What characterizes olfactory encounters “in the wild” is the unpredictability of the chemical stimulus in its environment and its interaction with the sensory system. I suggest that the olfactory system is primarily tuned to track and identify the chemical environment, not classify individual chemicals. More precisely, the olfactory system measures the statistics of a changing odor environment. What makes us identify that distinct fruity odor of peach may not be a determinate set of molecular features in isolation, but how the olfactory system has learned to differentiate specific molecular features from its encounter with other, similar ones.