Why do we have two nostrils?

Our underwater ancestors have two front nostrils to fill the nostrils behind and release water. The nose was then used only for breathing, not for smell.

The evolution of the nose as we know it today began when vertebrate animals came to the mainland in coordination with the displacement of two nostrils. At first, they were in the teeth, then moved down to almost.

Today in addition to breathing with two sinuses, we can feel the smell of what we are eating or the kind of water we are drinking.

When entering the nose, the air will pass through the throat, then be warmed and moistened behind. Part of the sinus is covered with a mucous membrane where millions of sensory neurons specialize in sensing the olfactory molecules that are immobile.

After fixing the ' odors ' in the surface sensing cells, a nerve signal is transmitted to the brain along the olfactory nerve. In addition to the mucous membranes, there is another nerve related to the sense of smell, which is the trigeminal nerve. Its ends react with chemical stimuli but only when compounds are present at high concentrations.

'We can smell a lot of smells, but only when the trigeminal nerve is stimulated can we clearly distinguish the odors,' study author Thomas Hummel of the department of ' Taste and Taste Sense of Dresden University Hospital (Germany) explained. Rapid and strong inhalation helps to distribute more efficiently the odor molecules in the nose.

Scientists have also demonstrated that the second nostril is not only used to smell many smells but also helps to breathe better. When smelling 50% of an odor in each nostril, it is felt more than sniffing with just one nostril.

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