Word: smells
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Dates: during 1990-1999
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...sense of smell is the most primitive of the five senses, a throwback to the primordial mists when the brain was scarcely developed. It is also the least understood sense. The human nose can distinguish an extraordinary bouquet of odors, some 10,000 in all, and other animals can better that. It has long been recognized that moths, for example, are exquisitely sensitive to certain pheromone molecules and can sniff out a potential mate half a mile away. But scientists could not begin to explain precisely how they...
...science, two researchers at Columbia University announced they have isolated what they believe are the first known odor receptors -- individual genes that are active in the nose and nowhere else in the body. What is more, the molecules they found seem to be part of an extended family of smell genes -- perhaps the largest single family in the long strand of mammalian DNA. "We have identified a few hundred genes," says Richard Axel, a professor at Columbia's Howard Hughes Medical Institute. "And there is reason to suspect there may be as many as a thousand...
...findings, published in the current issue of the journal Cell, suggest that the sense of smell may work very differently. When odor molecules drift among the millions of tiny cilia located high in the nasal cavity, they seem to slip into certain odor receptors like keys into locks. The fact that there are such a large number of different kinds of odor receptors suggests that much of the work of discriminating among smells is being carried out at a chemical level within the nose itself. Signals from these receptors are then transmitted to the olfactory bulb, the small region...
This makes a certain amount of sense from an evolutionary point of view. Although humans tend to treasure sight above all other senses, primitive animals probably relied more heavily on smell than on vision for their survival. And since their small brain size may have limited their capacity to process large quantities of information, they needed lots of specialized cells to do the work of identifying, say, the smell of food that had spoiled or the odors associated with fertility and reproduction...
...motley convoy stops before the small town of Altun Kupri, 25 miles from Kirkuk, and everyone jumps out. A truck with a flat tire zooms by from the direction of the city carrying wounded. One can smell the odor of burned flesh as it passes. As the twilight gathers, Abdul Rahman Aju Ali, 54, a barrel- shaped man with fierce eyes, explains, "We will attack at night...