Our noses are able to detect a wide variety of smells. From rotten eggs to paint to cut grass to dog breath, there’s something for everyone!
But for a long time, scientists believed that our noses could only recognize about 10,000 different scents. But new research shows that we’re capable of smelling a lot more than that.
Smells
Smells are important for human health, helping us recognize things such as poisonous plants or rotting food. They also help keep us safe by alerting us to fires or other dangers.
The human nose has been estimated to be able to detect about 10,000 different scents. But a new study suggests that the figure is far too low.
In a study published in Science, researchers tested volunteers’ ability to distinguish between a variety of complex mixtures. Using 128 different molecules, the researchers mixed them randomly in groups of 10, 20 and 30 to produce a wide range of smells, from grass to citrus.
The researchers found that people could discriminate between the odors so long as their molecular make-up overlapped less than 51%. Their calculation suggested that the human nose can detect at least a trillion combinations of odors, which is more than five times more scents than have ever been detected before.
Scents
A new study published in Science shows that our noses are capable of detecting a staggering 1 trillion scents. This is a huge boost from the old estimate of just 10,000 scents.
The researchers tested 26 volunteers by having them sniff out mixtures containing 10, 20 or 30 different odor molecules. These molecule combinations were created from a collection of 128 odor molecules, and each evoked an entirely different smell.
One of the odors they detected was camphor, which resembles cleaning fluids and can be found in things like mothballs and sea breezes.
Humans have a strong sense of smell, which is why we can remember certain scents and associate them with memories. We can even detect whether something is safe for us to eat or drink by smelling it.
Olfactory receptors
It’s a common misconception that humans can only distinguish between 10,000 different scents, but a new study suggests that our noses can tell us the difference between at least 1 trillion diverse aromas.
The olfactory system is a complex network of millions of sensory neurons that tuck into the mucous layer underneath the nasal cavity. These neurons extend hair-like cilia that contain specialized receptor proteins that detect odor molecules.
These receptors bind to the air we breathe, which triggers an electrical signal that travels to a region of the brain known as the olfactory bulb. This area then interprets the signals and relays them back to the nose so we can identify the odor.
The olfactory system has a lot of individual variation, and some people are more sensitive to smells than others. The researchers aimed to see how much odor diversity was needed for a person to distinguish between two vials that contained the same combination of ingredients, but were slightly different.
Olfactory neurons
The human nose is a powerful sensory organ that detects and remembers smells. It does so with a relatively small portion of the brain, but because of its complexity and individual differences, it’s an important part of the body’s overall function.
Several studies have found that people can discriminate among a large number of scents. In one, 26 volunteers were tested to see how well they could recognize mixtures of 128 different odor molecules.
They were given three vials containing two identical scents and one that had been mixed with an outlier. Vosshall and colleagues counted how often the volunteers correctly identified a different odor in each of the 128 combinations and extrapolated these results to estimate how many scents humans can distinguish.
However, a new paper published in Science by Rick Gerkin and Jason Castro suggests that last year’s stunning claim about how many smells the human nose can discern is not supported by the actual data collected. The researchers show that the number of smells estimated in the 2014 study is heavily dependent on the experiment’s parameters and the strictness of a statistical test the scientists used.