Why do humans smell worse than other animals?

A team of scientists, led by researchers from the Karolinska Institute in Sweden, has just discovered that the olfactory bulb – a structure in the vertebrate brain that processes sensory input from the nose – is distinguished from all other mammals in that, after from birth, new nerve cells no longer develop in it. This fact could be the reason whyhumans lack a sense of smell as keen as that of animals.

In most of theadult mammalsthey formnew neurons in two regions of the brain: the hippocampus and the olfactory bulb. Memory is related to the hippocampus, while the interpretation of smells occurs thanks to the olfactory bulb. Despite attempts to learn more about the formation of new nerve cells in the human brain, so far no conclusive answer has been reached.

The authors of this study solved the puzzle by calculating the age of the cells. To this end, they measured the amount of the radioactive isotope carbon-14 contained in the cells. Thus, they observed that the neurons of the olfactory bulb of adult human individuals had a concentration of carbon-14 that corresponded to that existing in the atmosphere at the time of birth. Consequently, later new neurons are not produced in this part of the brain, which distinguishes humans from other mammals.

“I have never been so puzzled by a scientific discovery,” acknowledged lead researcher Jonas Frisén, professor of stem cell research at the Tobias Foundation of the Karolinska Institute. “The logical thing would have been for humans to be like other animals, and especially apes, in this regard. But the truth is that heHumans depend less on their sense of smell for survival than many other animals, and this may be related to the non-generation of new cells in the olfactory bulb, although we can only speculate. “