> This might be an indication of the massive complexity of smelling: the human body has only four visual receptors, compared with more than four hundred olfactory receptors.

Sounds reasonable - after all, light is just electromagnetic radiation of a certain frequency, so evolution "just" had to "develop" a few receptors tuned to some of the most important frequencies. Same for hearing and sound waves. Smell however has to detect a huge range of chemicals in the air.

"Sounds reasonable."

No, it does not. Your eye has no receptors to detect a chair, a stone or a dog. They detect a spectrum. Why should the nose work different?

"infrared theory of smell - a theory that the olfactory sense organ functions as an infrared spectrometer. It assumes that odorants each have a unique infrared absorption spectrum, which produces transient cooling of the cilia in the olfactory epithelium."

This book will answer most of your questions: https://www.amazon.de/Sense-Smell-Robert-Hamilton-Wright/dp/...

This is not bad either

Luca Turin - A Method for the Calculation of Odor Character from Molecular Structure July 2002Journal of Theoretical Biology 216(3):367-85

Turin's spectral theory of olfaction has been disproven. I think even Turin himself admits that "perhaps it's not exclusively spectral", which means a lot, when you know Luca ;)

1. There is no proof in science. But now there is disprove? Link please.

2. The other book, while very old, addresses most critique points.

3. The US military has successful applications of this theory in creating non explosives odors of explosive substances for training dogs.

Ok, let's phrase it differently. In response to well-evidenced critique, raised after that 2002 book, the vibration theory of olfaction has been watered down so far that it is now arbitrary.

The wikipedia entry for the vibration theory of olfaction has plenty of links: https://en.wikipedia.org/wiki/Vibration_theory_of_olfaction?...

It didn't help the scientific debate that Turin's 2002 book contains some ad-hominem insults to scientists who had voiced challenges to his theory.

If the vibration theory has ever succeeded to uncover structure-smell relationships (like in the application with the US military that you quote), it is because the vibrational spectrum of a molecule encodes its shape and internal flexibility. It does not mean that all olfactory receptors perform spectroscopy, as Turin claimed (note the past tense - he stepped back from that claim at least 8 years ago).

3.1 Isotope effects 3.2 Explaining differences in stereoisomer scents 3.3 The sulfurous smell of boranes

Most of the critiques are debunked in the book from 1982 that I linked.

How can a book from 1982 "debunk" experimental evidence that has been obtained 20-39 years later? It cannot.

Much has happened in olfaction since 1982. A very small proportion of that work has actually debunked the vibration theory of olfaction.

It's a pity, since that theory had some very appealing properties. But it just doesn't align with the current experimental evidence.

edit: By the way, all of the observations mentioned can be explained by classical ligand-receptor interactions. No need for esoteric assumptions like spectroscopy performed by olfactory receptors.

"How can a book from 1982 "debunk" experimental evidence that has been obtained 20-39 years later? It cannot."

Well, it talks exactly about the points you mentioned and that are listed in Wiki. This book was decades ahead of its time. Seriously.

I know both sides of the argument.

There are anecdotal observations and theoretical arguments that support the vibration theory. But all aspects of it can be explained using less exotic models of ligand-receptor interaction. Proponents of the vibration theory are ignorant of those alternative explanations. The experimental evidence does not give a conclusive picture, either. Some experiments have clearly falsified aspects of the vibration theory, whereas the key experiments that support it suffer from systematic weaknesses.

Therefore, unless texperimental evidence appears that clearly supports that olfactory receptors perform electron-tunneling spectroscopy, I remain unconvinced.

Ok, let's phrase it differently. In response to well-evidenced critique, raised after that 2002 book, the vibration theory of olfaction has been watered down so far that it is now arbitrary.

The wikipedia entry for the vibration theory of olfaction has plenty of links: https://en.wikipedia.org/wiki/Vibration_theory_of_olfaction?...

It didn't help the scientific debate that Turin's 2002 book contains some ad-hominem insults to scientists who had voiced challenges to his theory.

If the vibration theory has ever succeeded to uncover structure-smell relationships (like in the application with the US military that you quote), the it is because the vibrational spectrum of a molecule encodes its shape and internal flexibility. It does not mean that all olfactory receptors perform spectroscopy, as Turin claimed (note the past tense).

> Why should the nose work different?

why would it?

AFAIK a lot of proteins are specialised wrt the many bio-chemical reactions of the body.

Good excerpts from a forthcoming book. I find a study of the "Sense of Smell" quite intriguing; it is one of the most primitive of the senses and affects our Brain directly (eg. Anaesthesia gases).

Can anybody recommend a good Scientific book on Olfaction?

What kind of book are you looking for? The "Springer Handbook of Odor" is a comprehensive reference, although it mainly covers the "input" side of things. If you're more interested in the Neuroscience of smell, you could try Chapter 6 in Liqun Luo's "Principles of Neurobiology".

BTW, anaesthesia is not mediated by olfaction, but by diffusion of anaesthetic agents into the bloodstream.

edit: if you are looking for a more general and accessible introduction, you could look at Charles Sell's "Chemistry and the sense of smell". It goes into reasonable detail but still maintains genral readability, unlike the science textbooks I recommended above.

Thank you for the recommendations.

I am interested in both a General Overview and Neuroscience specific viewpoints (specifically Memory/Emotions and Smell) and hence will take a look at the suggested books (have a Bachelors in Chemistry though long since forgotten!).

On a side note (since you seem to be knowledgable), can you recommend some good books on Neuroscience, The Brain/Nervous System and The Immune System?

Re Neuroscience and Brain/Nervous System I like Liqun Luo's Textbook that I mentioned above. I don't know much about immune system books unfortunately.

Concerning memory and smell, you'll most likely find information in the "popular science" category. Personally I am skeptical about the often-touted "special link" between smell and memory. I don't believe that this link is any more special than the one between vision and memory.

You could also look at Paolo Pelosi's "On The Scent" for a book on the sense of smell aimed at a scientifically keen lay audience.