Sense of smell
The sense through which odors are perceived.
The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. It has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste. In humans, it occurs when an odor binds to a receptor within the nasal cavity, transmitting a signal through the olfactory system.
- field
- Sensory biology, olfaction
- known_for
- Detection of odors via olfactory receptors; role in flavor, inbreeding avoidance, and guiding movement
- key_figures
- Eleanor Gamble, Lucretius, Linda B. Buck, Richard Axel, Luca Turin
Lore & Background
As the Epicurean and atomistic Roman philosopher Lucretius (1st century BC) speculated, different odors are attributed to different shapes and sizes of 'atoms' (odor molecules in the modern understanding) that stimulate the olfactory organ. A modern demonstration of that theory was the cloning of olfactory receptor proteins by Linda B.
Reader's Guide
The sense of smell is significant for its role in flavor perception, as retronasal smell plays the biggest part in the sensation of flavor, and the olfactory system is the only human sense that bypasses the thalamus and connects directly to the forebrain. It also contributes to inbreeding avoidance, as humans can detect blood relatives from olfaction, and MHC genes influence partner preference. Variability among vertebrates is notable: most mammals have a good sense of smell, while most birds do not, except certain species. Dogs have an olfactory sense approximately ten thousand to a hundred thousand times more acute than a human's. There are competing theories regarding odor coding, including shape theory, odotope theory, and vibration theory, but no theory yet explains olfactory perception completely.
Did You Know?
- The sense of smell is the only human sense that bypasses the thalamus and connects directly to the forebrain.
- Mothers can identify by body odor their biological children but not their stepchildren.
- Dogs have an olfactory sense approximately ten thousand to a hundred thousand times more acute than a human's.
- The odorant receptor OR6A2 has been linked to the preference or dislike of cilantro.
Frequently Asked Questions
What is the Sense of smell?
Olfaction is the dedicated sensory pathway that allows organisms to detect and identify airborne chemical compounds. It relies on specialized receptor cells in the nasal cavity that translate molecular binding into neural signals the brain can interpret as a distinct scent.
How does the Sense of smell actually work?
When a volatile odor molecule drifts into the nose and latches onto a matching olfactory receptor, that receptor fires a signal along the olfactory nerve toward the brain. This receptor-to-signal chain is what lets us tell millions of different scents apart.
Why is the Sense of smell important beyond just detecting nice aromas?
Olfaction helps organisms spot hazardous substances, identify compatible mates through pheromone cues, and even guide movement through an environment. In humans it also underpins much of what we experience as flavor, since smell and taste combine to create the full perception of food.
Who are the key figures associated with the Sense of smell?
Linda B. Buck and Richard Axel gained major recognition for mapping how olfactory receptors function at the molecular level, while thinkers like Lucretius, Eleanor Gamble, and Luca Turin contributed to understanding smell's biological, evolutionary, and physical dimensions.
What field does the Sense of smell belong to?
Olfaction sits squarely within sensory biology, focusing on how organisms translate chemical information into a perceptual experience. Its study naturally bridges neuroscience, chemistry, and evolutionary biology.
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