A study recently estimated that human beings can detect 1 trillion different smells. At least half of those smells apparently are found somewhere in the average high school boys’ locker room. (Just kidding!)
In the study, the researchers mixed different “odorant” molecules in combinations, provided participants with three vials of scents, and asked them to identify the outlier in the group. The participants were, on average, adept at distinguishing between the different smells. The researchers then multiplied the different combinations to come up with their estimate of one trillion. Believe it or not, one of the researchers is convinced that the estimate of one trillion — 1,000,000,000,000 — is almost certainly too low.
One trillion is a lot of smells, but the conclusion is plausible from an evolutionary standpoint. The researchers believe the odor-detection capabilities are directly related to the hunter-gatherer history of homo sapiens, because our distant ancestors relied on their sense of smell as a key component in their ability to track prey, sense enemies, determine whether food remained edible and water was potable, and otherwise detect danger. If you couldn’t smell a silently approaching saber-tooth tiger and skedaddle, or make a judgment that the fly-blown piece of woolly mammoth haunch that you were planning on eating for lunch remained edible, you weren’t likely to survive to reproduce.
The recent study joins other studies that indicate that human senses are remarkably discriminating. Along with the ability to use our olfactory capabilities to detect one trillion smells, other studies conclude that the human eye can distinguish between several million shades of color, and the human ear can discern 340,000 different sounds. Talk about sensory overload!