STOCKHOLM, Oct 4: Two US researchers, Richard Axel and Linda B. Buck, were on Monday awarded the Nobel Medicine Prize for pioneering work on our most enigmatic sense, that of smell, which helps us survive and enjoy some of life's subtlest pleasures.

How we recognize thousands of odours and remember them has long been a complete mystery to science, but Richard Axel and Linda Buck "have in several elegant, often parallel, studies clarified the olfactory system, from the molecular level to the organization of the cells," the jury said in its citation.

They discovered a large family of a thousand genes, and a corresponding number of olfactory receptor types. "A good wine or a sunripe wild strawberry activates a whole array of odorant receptors, helping us to perceive the different odorant molecules," the jury said.

The smell of a lilac in childhood provokes a print of a memory pattern amid the molecules which stays with us for the rest of our lives, allowing us to recognize the smell when we come across it again, and it activates associated memories.

"A unique odour can trigger distinct memories from our childhood or from emotional moments - positive or negative - later in life," the jury said. This faculty has been celebrated as one of man's great assets, most famously in Marcel Proust's novel Remembrance of Things Past, where the smell and taste of a single madeleine cake triggers a long string of memories.

But smell is not only about sensual experiences, it is also about staying alive in a dangerous world. "It is obviously of great survival value to be able to identify suitable food and to avoid putrid or unfit foodstuffs," the jury said.

For all new born mammals, smell is essential to find the teats of their mother and obtain milk. "Without olfaction the pup does not survive unaided," it said. Many adult animals observe and interpret their environment largely by sensing smell.

"To lose the sense of smell is a serious handicap," the jury said. Fish have just about 100 odorant receptors while mice, the species studied by Axel and Buck for a landmark paper published in 1991, have around 1,000. Humans have fewer receptors than mice, having lost some sense of smell during evolution.

Axel, 58, works at the Howard Hughes Medical Institute at New York's Columbia University, and Buck, 57, at the Fred Hutchinson Cancer Research Centre in Seattle, Washington.

"Well, I'm ecstatic, and quite surprised. It's really quite an honour," Axel said from California, where Swedish Radio called him after the formal announcement was made in Stockholm.

Normally, the Nobel committee notifies the winners, but Axel said he was shocked to learn the news from the radio's reporter - in the middle of the night, California-time - as no one had called him yet.

Asked what he was going to do after the phone call, Axel replied: "I'm going to have a cup of coffee." The prize rewards their contribution to the under standing of the human body, or physiology, rather than any immediate medical application, but their findings are beginning to be felt in many areas of daily life. -AFP