Mammals Have a Nose for Danger (Literally)

By Eliza Strickland | August 22, 2008 9:42 am

mouse danger noseA mouse’s nose has a cluster of specialized cells that respond to the chemical signals sent out by fellow mice that are in distress, researchers report, meaning that mice can literally smell fear. A lump of nerve cells in the nose tip called the Grueneberg ganglion responds to the “fear pheromones” of imperiled creatures, sending a signal straight to the brain. As Grueneberg ganglia are known to exist in rodents, cats, apes, and humans, researchers say it’s likely that the cells perform the same function in all mammals.

In a new study, researchers dosed water dishes with mouse alarm pheromones, and put the dishes in cages with both normal mice and mice whose ganglia had been removed. The contrast was very striking, [lead researcher Marie-Christine] Broillet said. “The normal mouse immediately gets scared and goes to the corner of the box and freezes,” she said. But mice without the ganglia carried on as before, seemingly unaware of the danger signals. Both groups were able to sniff out cookies hidden in their cages, however, suggesting the altered group’s sense of smell was otherwise unaffected [National Geographic News].

The findings, reported in the journal Science [subscription required], solve an old puzzle about the function of the Grueneberg ganglion; when it was discovered in 1973 scientists couldn’t determine its purpose, and it was then forgotten for over 30 years. Researchers rediscovered the structure a few years ago when mice were genetically engineered to produce a green fluorescent protein in their neurons, Broillet says. Scientists were surprised to see the clusters of green neurons sitting all alone at the tip of the mice’s noses [Science News].

Warning systems that help animals detect a threat to their own species provide a clear boost in survival odds, so researchers say it makes sense that the ganglia evolved early and are present throughout the mammalian family tree. Even certain plants release alarm pheromones to produce bitter and astringent tannins, so they can become less appetizing to hungry animals. In modern life, our own response to alarm pheromones might be hard to notice, but it is entirely possible that we still inadvertently react to their presence [Ars Technica].

Image: Science/AAAS

CATEGORIZED UNDER: Living World, Mind & Brain
  • Kim

    Now we at least know why animals freak out at the vets´!

  • beach bum

    This is SO INTERESTING! You know you can “feel” bad vibes when there is a fight breaking out, maybe we are actually smelling them! I wonder if we also can smell other emotions? Think about being at the happiest party, or wedding, or some wonderful gathering. Is part of what makes it so wonderful the fact that we are all producing “happy smell”?

    Where do the mice produce the smell from? Does it come out of an orifice or emanate from their skin?

  • Eliza Strickland

    It’s interesting — not much is known about alarm pheromones in mammals yet. Researchers aren’t even sure where in the body they’re produced. But the researchers “could collect the pheromones by simply stressing mice and sucking up the air around them,” the New York Times says.

    I just skimmed some of the scientific literature for the best guesses on these pheromones; it looks like they may be emitted by a gland in the groin, and may be “low-molecular-weight volatile substances.”

  • J Beran

    This is amazingly interesting. I would love to follow the progression of this research, especially as it follows into the world of finance. Possibly leading to more scientific explainations of ‘market panic’ on Wall Street and other major physical exchanges the world over. I have always wondered if and how a market crash or abrupt rally may better be explained by biology than psychology – though the two are obviously at fault.

    It is unfortunate that more of this research does not make its way into mainstream readings and teachings. Supervisors and managers would benefit greatly from understanding what makes their teams act as they do in extreme circumstances.

  • http://n/a john

    how come it has taken the scientist so long to come up with proof about what statements acquired brain injury owners often experience, somehow we end up being able to first smell when we or someone around us is in a physical dangerous situation then the intuitive sense kicks in but when we speak about what we feel we are either dismissed as being unable to recognized the after effects of our injuries or medicated to control our socially unacceptable outbursts.
    wait until the american and canadian tropps come back from the middle east and he afghanistan bomb blasts where they are not visibly injured then ask them how they know what their sense of smell tells them about what they are expeireinncing.
    great article lots of truth.

  • Richard

    where can I find more information about research into smell, pheromones etc?
    Many thanks

  • http://Facebook carol kaplan

    My dog found my cancer. I had lost 20 lbs and had gone to my doctor who did blood work, examined me and said I was fine. However my dog who was a “helper dog” who had literally got me walking again after spinal damage and so was probably very attuned to my body began sniffing my tummy and whining. He would paw me and look into my face with great concern. After two weeks of this
    I contacted a friend involved in medical research who was able to get me a rapid PET scan as a research volunteer. My cancer was found exactly where my dog was sniffing. If it wasn’t for his alarm I would be dead right now.


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