A woman smells a flower in the rose garden at the annual Chelsea flower show in London.

Four percent of left-handed women lack an olfactory bulb but can appreciate a flower’s perfume, according to analysis of data in a public repository. Credit: Dan Kitwood/Getty

Neuroscience

The women who lack an odour-related brain area — and can still smell a rose

The olfactory bulb was considered crucial for a sense of smell, but a chance discovery challenges the dogma.

When the aroma of fresh coffee hits your nose, odour receptors send signals to a brain region called the olfactory bulb, which then transfers this information to other areas of the brain. But now researchers have stumbled upon people who can still enjoy coffee’s fragrance even though they lack an olfactory bulb.

Scientists had thought that people without olfactory bulbs could not detect odours. But as Tali Weiss and Noam Sobel at the Weizmann Institute of Science in Rehovot, Israel, and their colleagues reviewed brain scans of healthy, left-handed participants for a smell study, they found two women who seemed to lack olfactory bulbs but could still smell.

The team then analysed brain-scan data from more than 1,000 people, including 606 women, and found that roughly 0.6% of women and about 4% of left-handed women had no olfactory bulbs but did have a normal sense of smell.

How these women identify odours is unclear, but it’s possible that their neurons have wired into olfactory networks elsewhere in the brain, the researchers say.