Culturing Science – biology as relevant to us earthly beings

Carnal Carnival: Body Odor Edition!

Welcome to the 6th edition of the Carnal Carnival, a blog carnival founded by Bora Zivkovic and Jason Goldman, dedicated to celebrating the traditionally gross in the animal world.  Previous editions have featured poop, vomit, decay and orgasm (which is less gross, but still pretty taboo).

This month of January 2011, the carnival features BODY ODOR!

I'm an artiste; don't judge

You know … when you go to the gym and there’s that one guy, shirtless and reeking of garlic, who happens to be on the treadmill next to you and you nearly pass out.  Or maybe it’s your best friend and, after months of avoiding having a conversation with her about her overwhelming odor, you just buy her deodorant for her birthday.  The smell of B.O. is imprinted upon each of our minds – a stench that sometimes makes us question why we have the ability to smell in the first place.

What is smell and why would we evolve this sense?  What we think of as smell – sniffing odors through our noses – is just a form of chemosensing, found in bacteria, ants, dogs, and, yes, humans.  We have chemoreceptors in our noses that pick up chemicals in our environment and interpret them.  Bacteria use chemosensing to pick up on cues in the environment, molecules of poison or food for example, and can then move towards or away from them.  Ants are well known for their pheromone trails which can alert other members of their colony to danger or to a food source.

The Search by xkcd

In a similar vein, humans have retained their sense of smell to identify food and poisons.  Because rotten food, such as the “smelly dead” illustrated by Viktor Poor of Stripped Science below, gives off such a rank smell and can also make us sick, we can learn to avoid poisonous food based on smell.  But that’s not all this sense does.  We like to think that we are far mightier than ants and that we have control over all our decisions based on mind and intellect alone.  But just like the ant, we also communicate messages to each other through pheromones given off in our sweat, our body odor, that we interpret without realizing it.

Drawing by Viktor Poor of "Stripped Science"

The Smell of Fear

Pounding heart.  Sweaty palms.  Sudden inability to speak.  Enhanced athletic ability.  These are all human reactions to fear.  When you’re scared or anxious or nervous, you feel them to your core – however, those around you might not be aware that you are so scared, much less why.  Thus there is a benefit to be able to communicate this emotion to the people around you, so that they can also be aware, alert, and ready to react.

Since there is not yet evidence of telepathy, sense of smell is the obvious way for individuals to communicate with one another non-verbally.

  • Does sweat produced when a person is anxious make others who smell it more likely to take risks? See this post at BPS Research Digest by Christian Jarrett
  • Can the smell of sweat produced by subjects in horror (watching horror films) cause others to be more likely to see threats where there aren’t any? See Neurocritic‘s post, “I Know What You Sweated Last Summer”

B. O. is sexy?

I have a friend who doesn’t shower too frequently.  Whenever his hair is looking a little greasy and he starts to smell a bit funky, someone will often joke to his girlfriend, “how do you put up with it?”  He’ll then stick his armpit in her face and, with triumph, yell, “She loves my smell!  She can’t get enough!”  Is there any truth to this?

  • Can a woman determine whether a man is aroused just by smelling his sweat?  See posts at both the Neuroskeptic and Christie Wilcox, at her old site
  • Can you identify your partner based on scent alone?  And does this ability vary depending on how “in love” she is?  See this post at Christie Wilcox’s site at Scienceblogs
  • Could there be another explanation for my friend’s cocky behavior? Scicurious of Neurotopia presents an interesting study correlating the attractiveness of a man, rated by women, with his self-evaluation of his own smell

For a great overview on this topic, read Jesse Bering’s post on his Scientific American blog, “Bering in Mind,” Armpit Psychology: The Science of Body Odor Perception.

That’s just rank!

Sometimes there’s nothing else to say but that.

  • How do you deal with people who have bad B.O. in public spaces?  Christina Pikas writes about B.O. in public libraries
  • Morning breath.  We all know about this particular breed of B.O. James Byrne of Disease Prone writes about this, and the broader bad-breath diagnosis of halitosis
  • People aren’t the only ones who can sense and have to deal with the stink of one another.  Read about how elephants can differentiate between different human ethnic groups based on smell alone on Ed Yong’s Not Exactly Rocket Science

To learn more about the evolution of pheromones, I recommend Dr. Kara Hoover’s recent review in the American Journal of Physical Anthropology, “Smell with Inspiration: the evolutionary significance of olfaction.”

Thanks for reading, and I hope you learned a thing or two about the science of human stench.

To end, I’d like to share the greatest human-produced smell of all: The Smell of Teen Spirit

Written by Hanner

January 24, 2011 at 10:01 pm

7 Responses

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  1. Great collection! Thanks for including my piece and I cant wait to get home and start reading through the others :D

    James

    January 24, 2011 at 11:11 pm

  2. So we’re allowed to say that humans have pheromones now? I thought some people didn’t think that was so.

    Kirsten

    January 25, 2011 at 11:02 am

    • Some people definitely think that, but I don’t see why they have any reason to. We’ve found pheromones in just about every other organism. Insects have pheromones. Fish. Amphibians. Mice. Dogs. Monkeys. Why would we suddenly lose them? I don’t know if naysayers are biased because the idea of a human pheromone would make us more animal and less rational. But in all the literature I’ve read, there were no doubts.

      Hannah Waters

      January 25, 2011 at 11:21 am

      • That’s how I’ve always felt about it. This is a fun carnal carnival. Also, great drawing.

        Kirsten

        January 25, 2011 at 2:46 pm

  3. N.B.: Friends were pleased at being referenced in blog post. In yet another expression of B.O. pride, E. reenacted the aforementioned behavior: “YOU LOVE THIS” while shoving her face into his armpit. M. replied: “wow, you are ripe today!”

    Hannah Waters

    January 25, 2011 at 3:15 pm

  4. Don’t perfume companies use animal pheromones to make their products which females of our species then use after removing their own scent with soap & water?

    Also, since our mammalian bodies evolved into our present human state, why wouldn’t they contain pheromones like other animals?

    By the way, Hannah, when is B.O. Pride Day being celebrated this year?

    R E Brindle

    January 26, 2011 at 8:26 pm

  5. [...] found any link to it, but I wasn’t much in here recently so I guess it’s sort of okay). Carnal Carnival. For gross posts. (Ah ah! my latest sentence had only one vowel, and this was the only reason I [...]

    New Carnival « Seeds Aside

    February 9, 2011 at 3:53 am


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