Human Sense of Smell Rivals That of Dogs, Says Study (theguardian.com)

One scientific analysis is arguing that the human sense of smell has not only been underestimated over the years, but that it may rival that of dogs and rodents. John McGann, a neuroscientist at Rutgers University in New Jersey and the paper's author, said: "For so long people failed to stop and question this claim, even people who study the sense of smell for a living. The fact is the sense of smell is just as good in humans as in other mammals, like rodents and dogs." McGann has reached this unexpected conclusion after spending 14 years studying the olfactory system. The Guardian reports: McGann identifies a 19th century brain surgeon, Paul Broca, as the primary culprit for introducing the notion of inferior human olfaction into the scientific literature. Broca noted that the olfactory bulb -- the brain region that processes odor detection -- is smaller, relative to total brain volume, in people compared with dogs or rats. The discovery inspired Freud's belief that human sexual repression may be linked to our "usually atrophied" sense of smell. In the latest paper, published in Science, McGann points out that in absolute terms the human olfactory bulb is bigger than in many mammals and a literature search revealed that the absolute number olfactory neurons is remarkably consistent across mammals. McGann goes on to deconstruct other metrics that have been used to support the idea that human smelling abilities are limited. Humans have approximately 1,000 odor receptor genes, for instance, compared to 1,100 in mice, which some had taken as confirmation of mouse superiority. However, other work suggests there is not a tight relationship between the number of olfactory genes and smelling ability. One study found that cows have 2,000 such genes - far more than dogs.

Comments

I'm calling horse hockey

[Snotnose]

I can't smell my own BO, let alone a nice stash of coke, weed, or vodka 2 feet from my nose.

Really?

[MrLogic17]

Find me a human who can compete with a bloodhound or beagle in tracking a person, based on smelling a old shirt.

Re:Really?

[ckatko]

Seriously. Just because one study (that hasn't been replicated yet, the fundamental requirement of science) say something, doesn't mean it invalidates ALL of our pragmatic knowledge and experience.

  - Police aren't using humans to track drugs and dead bodies buried under ground for 7 days.

  - As an engineer, it doesn't take a genius to look at the shape of a dog's nose verses other animals to notice the huge mass and evolutionary investment in their noses. We aren't using humans to hunt for truffles. Don't you think in the course of human history it would be easier to use our noses than DOMESTICATE AND TRAIN ANOTHER ANIMAL to learn what we want?

I mean, all we know from this snippet is we MAY have more "oder receptor genes." DO more genes = more smelling ability? And what is ability defined as? Maybe dogs can't smell [as many] types of different smells, but they can smell them BETTER at smaller parts-per-million. They may also be able to smell the DIRECTION the scent is coming from a thousand times stronger than us. Our nose is pointed DOWN, theirs is pointed FORWARD. Evolution doesn't just design stuff like that for shits and giggles.

  I mean, there are so many questions that the only thing we can really do at this point is go "Huh. Interesting." and go about our days until some REAL science starts confirming this study and exploring the actual implications. This is just clickbait at this point unless some actual EXPERTS show up in the comment section to elaborate their experiences and research.

Re:Really?

[93 Escort Wagon]

But a pig will work with any handler, and will consider any human to be their equal.

But some pigs are more equal than others.

Drug dogs debunked. Doesn't pass the sniff test

[raymorris]

Talking about the number of genes is a bit silly, agreed. If you want to compare the two, compare them directly. There are humans and dogs trained in smelling things (in the fragrance industry, for example). Run a direct comparison test. Also of course you could directly test having untrained humans and dogs smell for food and other items.

DRUG dogs, specifically, have not fared well in blind in blind tests. While *some* dogs are probably quite good, in testing the typical police dog consistently "alerts" on wherever the handler thinks the drugs are. Tests have been done in which the drugs are in box #1, nothing is in box #2, and the police handler is *told* the drugs are in box #3. A police dog is more likely to alert on #3, where the cop thinks the drugs are, then box #1, where the drugs actually are.

really?

[Goldsmith]

I've studied olfaction, and this just doesn't seem right. This olfactory bulb argument seems like a straw man that no one in the field has been using since... the 19th century. Digging in to the article a bit, it seems the authors of the actual study agree with me, and are using different odors for humans to balance out some of our... differences. Their main point (which is right) is that the human sense of smell is much better than most people realize, and that you can be trained to follow a scent trail, distinguish similar odors, and notice the cognitive effects scent has on you. Anyone who has experimentally studied olfaction for a few years will notice themselves gaining these abilities (it goes away quickly when you're not smelling things professionally several hours a day).

So why is this summary so wrong?

First off, humans only have 400 different olfactory receptors, it doesn't matter if genetics say you should have 1000, you only get 400 (genotype =/= phenotype). Second, you have less "sensor" surface area than other mammals in real terms, not scaled for size. Third, you lack the ability to concentrate scent molecules by varying your rate of breathing like other mammals (this can be overcome by varying breathing through your mouth and nose, but other mammals don't have to do this).

Re:Long-term training? [Re:Really?]

[narcc]

A handful of deaf people have learned to use echo location to navigate by making clicking sounds.

That would be very impressive, considering that hearing is seemingly essential to echo location. Still, I'm more than a little skeptical. I'll bet those fraudsters are really navigating by sight...