for National Geographic News
Mammals, including humans, have a built-in alarm detector in the tip of the nose for sniffing out danger, new research suggests.
The tiny sensor, discovered in mice, is used to pick up chemical warning signals sent by fellow animals in distress, scientists say.
Many plants and animals emit airborne molecules called alarm pheromones, which alert members of their species to dangers such as predators.
But how mammals detected these pheromones has been a mystery.
Now a team from the University of Lausanne in Switzerland says the answer lies in a microscopic ball of cells in the nose called the Grueneberg ganglion.
(Read: "Plant Networks Can Send Warnings, Spread Viruses" [October 1, 2007].)
The Grueneberg ganglion was first identified in 1973 in various types of mammals, including rodents, cats, apes, and humans.
These mammals probably all have a nose for danger, the study team said, although the discovery has only been made so far in mice.
The new discovery—to be reported tomorrow in the journal Science—was made during a study of the Grueneberg ganglion in mice using physiological techniques.
"The ganglion is the only [smell] sub-system that's completely functional at birth, so we were thinking it was important for nipple finding for the baby mouse," said study co-author Marie-Christine Broillet.
But after numerous tests for nipple finding and other possible functions, the team found that the ganglion played a role in danger communication.
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