Why rain and wet earth smell so good

Everything has a smell. In everyday life we ​​are in contact with hundreds of aromas, we like some more than others and this is something very subjective. However, there are certain smells that almost indisputably give pleasure to everyone. Can anyone deny, for example, that he feels a pleasant sensation with the smell of earth wet by rain? What is it that brings about that kind of relief that we experience when the drops of water begin to fall and everything becomes cool and wet?

O awesome.club wanted to know more about this scent. What is it exactly? Why does it smell so good? What we discovered really surprised us and helped us to understand that, in nature, there is always a why.

Those who know the subject assure that the sense of smell, the brain and memory are interconnected. This must have happened to all of us at least once: we walk down the street and an aroma invades us. Without thinking or reasoning a little, scenes from our childhood can come to mind. Perfume is sometimes nondescript; “smell of summer”, for example, or, more precisely, the smell of linden trees, coffee and wet earth.

The scientists and neurologists who investigate this relationship shed light on what it is all about. Although it looks like magic, it’s not. And the explanation is that the anatomy of the brain keeps smell, memory, mood and emotions connected.

The perception of odor is involved with the olfactory bulb, a neural structure located in the front part of the brain and considered primitive. Scientists believe that it was present in the brain of the first mammals.

This has probably happened to all of us more than once: after several very hot days, the long-awaited clouds form, the sky darkens, the rain comes and, with it, the smell of wet earth, wet stone and grass. It’s hard not to feel well-being when you’re surrounded by this fresh and sweet aroma. Generally, we are invaded by a series of positive feelings associated with this moment of comfort.

If we connect this sensation with the main function attributed to smell — that of detecting the elements that the body needs to survive and distinguishing them from those that may be harmful —, the theory defended by some scientists makes sense. According to her, our ancestors established a strong positive connection with the smell of rain, as it indicated the end of the dry season, which, in turn, increased the chances of survival. It’s just that the rain revives the plants, stimulates the harvest and, therefore, the production of food. It is neither more nor less than synonymous with life.

This unique aroma that we smell has an equally unique name: “petricor”. In 1964, two Australian geologists created this term to define a phenomenon they discovered: during periods of drought, plants exude an aromatic oil that is absorbed by the surface of rocks and dry soils and is released into the air, when in contact with the water. Water. Therefore, the longer the dry period lasts, the greater the accumulation of oil and the stronger the aroma when the rain finally falls.

But this scented oil has an important function. The two researchers observed that it inhibits seed germination and, therefore, concluded that plants could generate it to prevent their growth in periods of drought, when it would be more difficult to survive. But aromatic oil is just one of the compounds responsible for generating that special scent. Have more.

In order for this very particular aroma to be generated, these oils that are in the air combine with another substance, geosmin (another difficult word). It is a substance generated by a group of bacteria and some fungi that inhabit the soil and that is noticeable when the earth is wet. These organisms secrete the compound by producing spores. Then, the force of the rain that falls on the ground sends these spores into the air, which carry the aroma to our nose.

Studies have revealed that our sense of smell is extremely sensitive to geosmin; some people can detect it at really low concentrations. This explains why we can smell the aroma when it is not raining where we are, but in nearby areas. If the wind is strong enough, it can carry this perfume where the water has not yet reached.

The production of geosmin by this group of bacteria also has a purpose related to the preservation of life. A study has shown that the aroma guides springtails, tiny beings with an appearance close to that of insects, to the bacteria responsible for the aroma. They follow the trail of that perfume because they know that their food is there. Now why would bacteria do that? Why would they help their “predators” to get to them?

Everything has a purpose, even for micro-organisms: these, in exchange for a “snack”, guarantee their proliferation. Yup. Springtails, after eating, take the bacterial spores with them and, thus, this colony guarantees the conquest of new habitats.

Plants exude aromatic oils to protect the life of their seeds; bacteria secrete geosmin to ensure their reproduction; we smell wet earth and somewhere in our memory we remember that this is a sure sign of survival. Confirmed: in nature everything has a why.

Do you have any other data that we haven’t told here about the scent of wet earth? Do you know the explanation of other aromas that are also pleasant?