I was investigating substances contained in the air, and I learned that air also contains volatile low-molecular-weight chemicals called odorants. When we inhale air, the odor information captured by our olfactory cells is transmitted directly to the brain. Of the five senses, only the sense of smell is transmitted directly to the brain. Is this because we need to instantly detect danger or process a lot of information at the same time? The sense of smell seems close to life.
https://www.brainscience-union.jp/trivia/trivia3308
Certainly, our senses of sight and hearing capture the propagation of light and sound, and seem to obtain information from a little distance. In comparison, our senses of smell, taste, and touch are when the object itself is already in contact with our sensory organs, so if there is a danger, we may need to make a quick judgment. Still, it’s amazing that our noses can identify the tiny molecules that are the source of smell. Some say that the sense of smell is the ultimate molecular recognition device.
https://park.itc.u-tokyo.ac.jp/biological-chemistry/profile/essay/essay31.html
Plants use this smell to communicate. They use the smell to attract insects and birds that carry their seeds, and to defend themselves by using smells that they dislike to avoid being eaten. Plants also use smell to let each other know when they are being eaten by insects, and to attract the insects’ natural enemies and defend themselves. It seems that smell is also an important source of information for insects, such as the smell of these plants and the pheromones of their peers. Scents are amazing.
https://healthist.net/nature/2147
I thought that smells were only in the air, but fish have a sense of smell too. It may seem obvious, but fish can smell odorous substances dissolved in water. They have a sense of smell that is nearly 300 times stronger than humans. It is well known that dogs and cats have excellent senses of smell, but fish’s sense of smell is comparable to theirs.
https://fishingjapan.jp/fishing/3712
There are apparently more than 400,000 types of odor substances, so there is a lot of information contained in the air. It seems quite difficult to be able to identify such complex molecules in the air. When it comes to developing sensors that mimic the five senses, it seems that the sense of smell is the most difficult to realize. The sense of smell is amazing.
https://xtech.nikkei.com/atcl/nxt/column/18/01085
There seems to be an expression that the world is full of scents. The invisible air is full of scents. It’s strange how the molecules emitted by countless living things and substances float in the air, which we perceive as smells, breathe in, and take in some of them into our bodies. It seems as though each one operates as its own life form, yet is also one with the countless molecules on Earth. I think it’s quite amazing that we can smell the existence of things even though we can’t see them. Smells are amazing. The Earth is amazing.
