Older research suggested that human sense of smell was not as great as the sense of smell of other animals, for instance. However, scientists discovered that it might not be like this. From certain points of view, our sense of smell might compare to that of dogs. Researchers traced back all the theories and put up a comprehensive study on the matter.
Challenging the theory that human sense of smell is poor
John P. McGann analyzed the smell receptors of humans, compared them to the cells of other creatures, and then searched the origin of the theory that humans had a poorer sense of smell than other animals. He discovered that humans have, indeed, fewer smell receptors than animals. However, this does not affect their olfactory senses. They are more sensitive to some smells, while animals are more sensitive to other smells.
Our sense of smell evolved throughout the years to match the conditions early humans lived in. Studies on ancient human populations analyzed their evolution, and also discovered how their sense of smell had changed.
DNA accounts for variations in how we sense certain smells
Humans have a smell receptor called OR7D4. This allows them to feel a particular scent found in boar meat, called androstenone. However, not all humans feel this scent in the same way. Some might find it sweet, while others might think it is foul and nauseating. Others might not even feel the smell at all.
The differences in how humans feel androstenone are accounted for by DNA variations. These variations occur among different regions of the world. For instance, people from Africa are more likely to sense this scent, while those living further in the north cannot feel it. These differences occurred for the first time in our ancestors, Neanderthals and Denisovans.
Neanderthals could smell androstenone. Denisovans were also able to sense the smell, but they have a unique mutation which affected the structure of the OR7D4 receptor. Researchers also think this different perception of smell might account for various food choices around the world.
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