The Skunk Behavior or Why Some People are Insensitive to Sweat Odors

It's partially in the genes

By on November 2nd, 2007 12:08 GMT
You know the typical 'skunk' in each company. It can be big, hairy and very pleased at how people panic when they see him. He should know that it's not the mighty blubber-filled body that which makes an impression on them; they are rather looking for the gas mask.

But don't blame him for a new research shows that their smell genes could be highly incapacitated. The new study led by Prof. Doron Lancet and recently published in PLoS Biology reveals that the difference in how humans perceive smells is partially genetic.

Of course, humans are visual beings (90 % of the information on our environment comes through our eyes), partially auditive and touchy, but the sense of smell is rather vestigial. Still, we can detect up to 10,000 different scents.

Rodents, like rats and mice, have a highly developed smell (as they are nocturnal, smell is much more valuable to them than vision is), but - surprisingly enough - humans and mice have the same number of different genes (about 1000) encoding proteins which are smell-detecting receptors in our olfactory membrane. Still, in the human lineage, more than 50 % of these genes have been shut off in the last million years.

But how and how many are deactivated in humans varies a lot amongst individuals.

Lancet's team, comprising researchers from Israel and Florida, asked their human subjects to sniff different solutions of chemicals smelling like banana, eucalyptus, spearmint, or sweat, at various levels. The ability to feel each odor was associated with their degree of receptor gene loss.

This is a breakthrough: the researchers discovered a gene (dubbed OR11H7P) which was connected with the capacity of detecting the sweat scent. A complex process boosted olfactory sensitivity to the sweaty scent of isovaleric acid in humans. When two genes were inactive in people, the individuals were totally unaware of the sweat stench, while those highly sensitive to the sweat smell possessed at least one functional gene.

But the story got more complicated, as women were on average a little more sensitive to various smells than men were, and the sensitivity to smells varied also amongst individuals of both genders. And the team also found that this variation was not entirely genetically determined; environmental factors were also involved.

In the end, there's no excuse for those skunks...Get a shower, dudes!