In comparing humans to other animals it’s pointed out how pitiful the human sense of smell is, compared to that of other animals. And yet in reading books on the Congo Pygmies and other hunter gather peoples, it’s often mentioned how they use their noses and acutely sensitive sense of smell to find food and follow game in the dense forest, in a manner that seems almost magical to the western observer.
Does our sense of smell really suck that bad, or is it simply untrained in modern humans?
No, it really does suck that bad. Our vision, on the other hand, is about as good as it gets for a mammal. There’s a trade-off there.
I herad that part of it has to do with the surface area of the olfactory nerves in humans vs other animals. Humans had proportionally small amounts of olfactory nerves in their noses.
We’re also very far up of the ground, where the real odors are.
What they said. As I recall, astro, you’re something of a mild SF fan. If I’m remembering correctly, you might enjoy Spider Robinson’s Telempath, which deals with the aftereffects of a tailored virus that gives humans the equivalent of a lupine sense of smell.
It’s not just humans. Monkeys and apes also have a weak sense of smell compared to many other animals.
In fact, there’s some speculation that primates’ poor sense of smell helped in the evolution of their big brains. Since they can’t smell that “hey, there’s a berry under that leaf,” they need to have a brain that thinks, “hmm, there could be a berry under that leaf. I think I’ll check.”
Can you imagine what it would be like to have the olfactory senses of a dog?
You’d never get anything else done.
This reminds me of a somewhat relevent question. Do any other animals react negatively to certain smells? Dogs seem to love the smell of everything, even stuff that smells awful to us. Is there any smell that would disgust them?
Both, actually.
Human sense of smell is significantly poorer than that of many other species.
But what sense of smell we have is often significantly under-used, too.
Dr. Richard Feynman would do experiments/parlor tricks where he would identify which books from a bookshelf people had handled. Sometimes he could even identify which person had handled which book. All done by using the supposedly ‘weak’ human sense of smell.
Humans seem to use their other senses and their brains more, and don’t need smell as much as other species, so they generally neglect it. Some humans, however, do have a well-trained sense of smell. Like chefs, medical diagnosticians, etc.
The smell of the vet’s office.
It’s a matter of loss of olfactory receptors (ORs) through mutation. Some 70% of human olfactory receptor genes have been disabled over the course of primate evolution. In chimps and gorillas about half of the ORs have become nonfunctional pseudogenes.
See [url=“http://www.pnas.org/cgi/content/full/97/6/2870”]The olfactory receptor gene repertoire in primates and mouse: Evidence for reduction of the functional fraction in primates
Let’s try that link again
Skunk.
Your sense of smell is more acute than you probably realize. You “tune out” most of the every-day odors around you-- you’re so used to them, you don’t even notice them any more.
Think of your last visit to the zoo. When you first entered the primate house, the stink of monkey shit was probably quite powerful. However, if you lingered watching the chimps, the smell “faded.” However, if you left, and returned say an hour later, you would notice it again.
It’s much like when you apply perfume or cologne. After a few minutes, you no longer smell it, but those who come in contact with you do.
I’ve read that astronauts returning to earth after a lengthy stay in space are sickened by the odors when they leave the ship. They smell not only the scents of the tarmac, but the smell of all of the soaps, hairsprays, colognes, deodorants, detergents and fabric softners on the bodies of those who greet them.
Our brain may automatically filter out a lot of the olfactory information it recieves in order to keep its circutry from being overloaded. Or, perhaps its that our brains can only process a certain number of scents at once. In either case, we smell a lot more than we realize.
I know my dogs never get anything accomplished. 
Insects, I think. I remember a couple of instances where my Gordon Setter smelled bugs up close (usually cicadas) and absolutely recoiled.
My friend’s dog seemed kind of bugged when I farted in her face. Could have been the sound, though, I suppose.