Using a tool they created known as the isotropic fractionator, they realized that women have more brain cells in their olfactory bulbs than men do. This is the region of the brain that allows us to smell. Published in the journal PLOS ONE, this study used the fractionator to determine the number of cells in the bulbs of men and women, which is how they came to their conclusion.
When someone breathes in through their nostrils, the first region of the brain to detect this signal is the olfactory bulb. Each individual has a different threshold for the ability to interpret smells. However, scientists have found that women outperform men in terms of tests measuring one’s ability to smell certain odors. Theories have focused on sex differences with regards to smell in the form of cognitive and emotional effects. Studies before this one have looked at brain scans of men and women to find volume and structural differences that might be behind the phenomenon. Most have not been effective in answering these questions.
As a result, researchers attempted to measure these differences on a smaller biological scale. They examined the post-mortem brains of 11 women and 7 men who were relatively healthy and over the age of 55 when they passed away. None of these people had worked in jobs where it was necessary to have a superior sense of smell. After measuring the number of cells in the olfactory bulbs of men and women with the help of the isotropic fractionator, scientists found that women had 43% more brain cells in this area compared to men.
After including neurons into the count along with the other brain cells, the team discovered that women had up to 50% more cells in their olfactory bulbs. Although they admit more research is necessary to prove these conclusions, one of the head researchers of the study noted that “larger brains with larger numbers of neurons correlate with the functional complexity provided by these brains. Thus, it makes sense to think more neurons in the female olfactory bulbs would provide women with higher olfactory sensitivity.” Scientists must still figure out how the brain creates more cells for this region, and theories suggest women developed this ability to bond better with their offspring and find potential mates.