Genes linked to whether you like his scent

McClatchy Newspapers
Published Monday, September 17, 2007

DURHAM, N.C. -- Like his smell when he's worked up a good sweat? Or would you rather not touch his drenched gym shirt with a 10-foot pole? Whether you love his smell or hate it may be up to your genes, according to researchers.

People have long thought that human likes and dislikes for a certain smell -- think gasoline or cilantro -- are cultural or based on experience, said Hiroaki Matsunami, an assistant professor of molecular genetics and biology at Duke University. But according to the researchers, who published their findings Sunday in the journal Nature, genetics play a role in how people perceive a particular odor.

Matsunami's lab, in collaboration with a team from the Rockefeller University in New York, has found a correlation between a variation in a particular gene and people's likes, dislikes or inability to smell two chemicals.

For the study, they tested people's ability to smell -- and reaction to -- androstenone and androstadienone, which are byproducts of the natural breakdown of testosterone in human males and secreted in sweat and urine.

Most people can't smell the chemicals, Matsunami said. Of those who can, many people say they smell awful -- like urine, he said. There are some who think the smell is faint and sweet, like vanilla.

Hanyi Zhuang, a graduate student in Matsunami's lab, falls into the latter category.

"I would describe it as a perfume-like odor. That's good for me because I couldn't work with an odor that I don't like," she said.

A Sunday visit to the lab found Zhang pulling on latex gloves before handling a small vial of androstenone.

She's so sensitive to it that if she touches it with her bare hands the smell lingers for hours, she said.

To a visitor, it smelled mildly of rubbing alcohol.

Zhuang identified an odorant receptor in humans that responded strongly to the chemicals. Her lab then collaborated with researchers at Rockefeller, who presented the smell to almost 400 volunteers and then took a sample of their blood to study their DNA.

The findings add to a scientific debate over whether or not humans use pheromones, which are chemical signals used by animals to communicate alarm and directions or for mating.

Animals like rats and dogs have about 1,000 functioning odorant receptors. The decoding of the human genome showed that while humans have about 1,000 olfactory receptor genes, more than half of them are pseudogenes, or basically destroyed, Matsunami said. Humans have fewer than 400 left functionally intact.

"But that doesn't mean that we no longer depend on olfaction at all," he said. "We do still have hundreds of genes."

Matsunami hopes to build on this research by studying human physiological reactions to the chemicals, such as amount of sweat produced and amount of cortisol in the body. Cortisol, a hormone, is induced by stress and will change functions such as heart rate and the blood pressure, Matsunami said.

"My gut feeling is that, yes ... humans do have some chemical communication like pheromones but in the modern society it's very difficult to show a direct effect," he said.

As for smell playing a role in human attraction?

"If they hate the smell, then I guess it's difficult to be together for a long time," Matsunami said.

Eli and Amy Kovick think there's something to it. The couple, who have been together six years, were picnicking in Carrboro, N.C., with their two young children Sunday.

Eli recalled breaking up with a girlfriend when he was 14. "Ultimately, I don't think I liked the way she smelled," he said. Even years later when he saw her, he noticed she still smelled the same way.

Amy says she doesn't mind Eli's smell when he sweats. "I kind of like it," she said.