The myth of human's poor sense of smell

[grampahol]

For years, at least back to the 19th century we have been taught humans have an inferior sense of smell to other animals. There is new research that indicates our sense of smell, as well as other creatures senses are more in tuned with evolutionary needs. We smell certain things or differentiate odors differently. An example might be dogs smelling butts and seemingly enjoying it while it's almost always offensive to us which doesn't mean our senses are inferior, just that we interpret differently.  We can smell an orange peel and find enjoyment while dogs and cats will back away like it's on fire and will kill them.. Dogs are often used to track odors, but we can as well under the right conditions. For example a dog can smell a pretty benign odor of certain drugs like cocaine and be trained to react. On the same hand a human could be on a subway or walking down an alleyway, smell vomit or old urine and immediately leave for a much more crowded area with many more people. Dogs? They'd probably eat it for lunch..  We interpret it all differently.. 
Anyway, this is mostly from an article in the NYTimes, https://www.nytimes.com/2017/05/11/science/human-sense-of-smell-nose.html?action=click&module=RelatedLinks&pgtype=Article

[fredtoast]

Can't read without a subscription, but there is no way in hell humans can small as good as dogs and other animals.

We would not train dogs to sniff stuff out if humans could do it. Humans would have never relied on dogs for tracking and hunting if we could have done it.

We may be "tuned" to react differently to different smells, but we can't small as well as animals. Not even close.

[grampahol]

(02-08-2022, 05:50 PM)fredtoast Wrote: Can't read without a subscription, but there is no way in hell humans can small as good as dogs and other animals.

We would not train dogs to sniff stuff out if humans could do it.  Humans would have never relied on dogs for tracking and hunting if we could have done it.  

We may be "tuned" to react differently to different smells, but we can't small as well as animals.  Not even close.

Not as good as dogs, but not quite as gross either. We do have selective smell however and distinguish certain things dogs cannot such as certain spoiled foods dogs will gobble right up and certain compounds that can kill us. Where we have the advantage of course is both brains and binocular vision and the ability to manipulate things much easier. It's just not quite as simple as saying dogs are a gazillion times better at smelling everything and stopping there. The ability to distinguish certain smell very quickly is something we do very well. I have a hunch there's another thing about smell that's never discussed and it may relate to hearing in how different animals hear different sound waves while others simply drop away. Taste, sight, hearing and smelling are all done within just millimetres of each other. Personally, and it's only a guess on my part that there are quite a few senses that do things we can't quite understand and many as we already know happen at an unconscious level ..
Anyway, we as humans aren't quite as smell limited as we're lead to believe.
I do know that you can be conditioned to not smell certain things after awhile.. Ask anyone who has ever delivered pizza for a living.. After a short period the smell of fresh hot pizza loses all appeal in a car..

[Sled21]

A German Shepherd dog's sense of smell is 10,000 times more acute than a human. That's how they can smell cocaine in a coffee filled container that has been shrink wrapped and stuck up in the rotten fender of some POS truck.

[reuben.ahmed]

As you said it's due to evolution. Dogs can't see as well as us, so they may have adapted with smell. We also can't see as well as some animals, or the spectrum we see is not as wide.

Spiders can see ultraviolet and snakes sense infrared - why not us?

[grampahol]

I didn't explain it very well so here's the original.. In no way is it claiming we are going to be dog sniffers, but we can likely interpret what we smell better than we imagined. Some, quite a bit is thought to be at the sub conscious level such as fear, illness, mate selection, etc..

Quote:By Joanna Klein

• May 11, 2017
  

By shoving her nose against a fire hydrant, your terrier may be able to decipher which pit bull in the neighborhood marked it before her. But that doesn’t necessarily mean she’s a superior sniffer.
Still, it’s conventional wisdom that humans’ sense of smell is worse than that of other animals — dogs, mice, moles and even sharks.
This belief isn’t based on empirical evidence, but on a 19th-century hypothesis about free will that has more in common with phrenology than with our modern understanding of how brains work. In a review published Thursday in Science, John P. McGann, a neuroscientist who studies olfaction at Rutgers University, reveals how we ended up with this myth. The truth is, humans are actually pretty good at smelling our world.
“We’re discovering, to our delight, that the human smell system is much better than we were led to believe,” he said. It may be different than other mammals’ “but actually in ways that suggest that it could be more powerful than mice and rats and dogs.



This is how the human nose works. All day long special cells inside the nose capture chemicals from the sensory environment around us, sending signals to a squished blob of brain called the olfactory bulb. The bulb then sends information about what odor is in the nose to other parts of the brain that work together to make sense of it all, associating these smells with other stimuli in our environments or with memories or emotions we have experienced before.
The myth that trivializes this complex process began with Paul Broca, a 19th-century French physician who studied the human brain to understand what made us different from other animals. He compared its large frontal lobe and, below it, the squished region for smelling with the plump olfactory bulbs situated in front of the brains of other mammals. Then he categorized animals into what were basically called the smellers (most mammals) and the non-smellers (including humans).
Dr. Broca argued that big olfactory bulbs compelled animals to succumb to earthly desires, while humans had free will nestled within big frontal lobes, which helped them overcome the urges caused by sensing odors. Other scientists simplified his findings without testing any animal’s actual abilities. Sigmund Freud even suggested that mental illness arose from the weakened or unused human sense of smell. By 1924, a major textbook described human olfactory bulbs almost as if evolution of higher thought had shrunken them to near useless, atrophied blobs.
Today many of us learn that our pancake of an olfactory bulb isn’t of much value because other animals have relatively bigger systems to process odors. We may think that our ability to see the world trumps our need to smell it. And introductory psychology and biology textbooks still say we can discern only about 10,000 odors. But smell influences our behavior, memories and emotions. There’s little or nothing to prove it any less important than vision, and we can actually sift through billions, possibly trillions of odors.
So it’s true that your dog is so good at sniffing partly because she has an extrasensory organ, around 50 times more receptors, and 40 times more space in her brain, relatively speaking, to process scents. But it’s also true that you can smell a banana just as well as she can.



“Different animals in different ecological niches have different problems they need to solve,” Dr. McGann said.
What matters may not be the size or the space in the brain devoted to smelling, but other things like the ways our smell or brain systems are wired or used. Mice and humans’ olfactory bulbs, for example, differ in relative size, but the number of neurons inside them are pretty similar.
“We’re all trying to understand the same sensory world, so if you’re a really big animal you might need to have more neurons devoted to touch because there are a lot of spaces you can touch on,” Dr. McGann said. “But you don’t necessarily need to smell more smells because you’re bigger.”
And there’s a lot we can do with our noses. Like our dog, we can follow a scent trail if we try. We can detect the sour ping of vomit and decide to move from an otherwise empty subway car to the packed one next door. We can tell by a person’s odor if he works in a coffee shop. And though the evidence isn’t solid, some scientists think we can select mates, detect fear or stress, or find out if someone is sick by smelling another person’s sweat, blood or urine.
“There’s a true underappreciation for the way we use our sense of smell that contributes quite significantly to our overall well-being, the way we appreciate food and the way we interact with our environment,” said Johannes Reisert, who studies olfaction in rodents at the Monell Chemical Senses Center and was not involved in the review.
And a better appreciation of the powers of human olfaction could be important, Dr. McCann said. We could forge new paths to solving problems in medicine, social communication and emotional processing, like the consequences of a malfunctioning sense of smell.