SCIENCE -SMELL- SCIENCE : LAB

The ' EEEWW ' Reaction

Why our ancestors were OK, going without deodorant

When you take a whiff of something, odor molecules sail into your nose, where they bind to proteins called the olfactory receptors - on cells that line your nasal cavity. These receptors trigger signals that your brain identifies.

A team of scientists has identified the olfactory receptors for two common odor molecules : a musk found in soaps and perfumes and a compound prominent in underarm sweat. 

The team discovered that recent evolutionary changes to receptors have already altered people's sensitivities to those odors.

The researchers think their findings support a hypothesis that the primate olfactory system has degenerated over evolutionary time.

But Kara Hoover at the University of Alaska Fairbanks, who was not involved in this research and who studies the evolution of human smell, thinks they could suggest increased olfactory discrimination.

And she raised other questions : '' Our species is really young. Why this much variation in such a short period of time? Is there an adaptive significance? ''

Olfactory receptors can be traced back hundreds of millions of years and are believed to be present in all vertebrates. 

Humans have around 800 olfactory receptor genes, but only about half of them are functional, meaning only half produce proteins that detect odor molecules. [ Sam Jones ]