STOCKHOLM, Sweden - American researchers Dr. Richard Axel and Linda B. Buck shared the 2004 Nobel Prize in physiology or medicine on Monday for their work on the sense of smell - showing how, for example, a person can smell a lilac in the spring and recall it in the winter.

Their genetic work revealed a family of "receptor" proteins in the nose that recognize odors, and they illuminated how the odor information is transmitted to the brain.

Axel, 58, of Columbia University in New York, shared the prize with Buck, 57, of the Fred Hutchinson Cancer Research Center in Seattle. Both are investigators with the Howard Hughes Medical Institute.

They reported finding genes for odor receptors jointly in 1991, when Buck was working in Axel's lab, and have since worked independently.

The Nobel Assembly at the Karolinska Institutet said the sense of smell "helps us detect the qualities we regard as positive. A good wine or a sun ripe wild strawberry activates a whole array of odorant receptors."

Academy members tell The Associated Press that the decision to give the pair the award was not in light of any medical or commercial payoffs, but rather to honor their exploration of one of the humanity's most profound senses.

For two scientists to single-handedly map one of the major human senses is unique in the history of science, Nobel assembly chairman Goeran Hansson told the AP.

The awards are always presented on Dec. 10, the anniversary of Nobel's death in 1896.