Humans Can Distinguish 1 trillion Smells

The least researched sense out of five human senses is the sense of olfaction or smell. We know what is the audible frequency range for our ears, we know our eyes can only detect wavelength present in the visible spectrum of light and ultraviolet or infrared light cannot be detected by the naked eye. We know how touch receptors work and that different areas of tongue have taste receptors for different tastes but we have never known how many smells can human olfactory system detect.

There has been a common belief that humans can smell 10,000 different odors but a new research proves this number to be far greater than that. Humans can detect one trillion odors.

Leslie Vosshall and her colleagues at Howard Hughes Medical Institute carried out this research. They took 128 different odor molecules that represented a wide range of smells like grass ,citric and random chemicals and combined them into unique mixtures containing 10,20,30 different components. They asked volunteers to smell those mixtures. Each volunteer was given three vials of scents at a time, two that were identical and one was a slightly different mixture. The subjects were asked to tell which mixtures smelled different. It was found that people could distinguish the different smells, if the components varied by 50%. Each volunteer made 264 such comparisons. Scientists then tallied how often their 26 subjects could identify the correct smell. When extrapolated how many different combinations of 128 odorants on average a person could differentiate, the result was one trillion.

However, individual capacity to detect the number of smell varied. The person who could detect the least number would be able to detect 80 million types of smells whereas best smeller would be able to distinguish more than a thousand trillion odors.

This overwhelming number of detectable odors can present its use anywhere you go and see a new thing, you will be able to smell its unique scent. Plants are evolving new smells, the world around us is constantly changing and if our sense to olfaction is this much evolved, we will be ready to adapt in new environments. Not only that but it can enable perfume manufacturers to make new, pleasant and unique perfumes.

[Source: HHMI | Image Credit: Tofugu]