Does our sense of smell favor processed foods?

Was fascinated to read an article based on a review paper published in the journal Science about the human sense of smell:

https://www.vox.com/science-and-health/2017/5/11/15614748/human-smell-good-science

The Science paper's author, John P. McGann contends, I think successfully, that the human sense of smell is demonstrably better than we have believed.*

What struck me, though, was not that we have a good sense of smell—think of all the perfumes that have been created, each subtly different from the next, and you realize how important smell is to humans and how exquisitely sensitive we can be. 

Rather I was intrigued to learn that we are superior to other animals in smelling components of food, but not just any food: human food that requires processing like cheese and coffee and roasted meats and beer and wine (no data on tea as yet, though).

Here is a picture of a dog following the scent trail of a pheasant and one of a human following the scent trail of chocolate oil, from the vox.com article. Clearly the human goes less astray! Of course you could always argue motivation: the human may have been more motivated and the dog occasionally distracted. The fact remains, nevertheless, that the human does a pretty good job!

So what components of food are humans able to smell at lower concentrations than can other mammals? This question has NOT been studied extensively, but the Science article cites three compounds: 

• n-pentanoic acid, also called valeric acid, which has a dairy, slightly fruity quality, and is found in milk, cheese, yogurt, coffee, as well as some fruits, including bergamot (Earl Grey, anyone?);**
• n-octanoic acid, aka caprylic acid, that has a waxy, fatty, rancid, oily, vegetable, cheesy quality, and is found in a host of foods, notably (for my thesis) beer and wine;** 
• 3-mercapto-3-methylbutyl formate, which has a sulfurous (that's the mercapto-) aroma, mixed with a caramellic, onion, coffee, roasted meat quality, and is found in beer and coffee.***

Laska and his colleagues suggest that perhaps each species' smell capacity is adapted to their dietary niche. 

It is interesting to contemplate that humans have developed a repertoire of olfactory receptors that are particularly attuned to the uniquely human foods that require processing for their development, like dairy products, and beverages, and possibly tea. Awaiting further studies!

* John P. McGann. Poor human olfaction is a 19th-century myth. Science 12 May 2017:
Vol. 356, Issue 6338, eaam7263. DOI: 10.1126/science.aam7263

** Selçuk Can Güven and Matthias Laska. Olfactory Sensitivity and Odor Structure-Activity Relationships for Aliphatic Carboxylic Acids in CD-1 Mice. PLoS One. 2012; 7(3): e34301.
Published online 2012 Mar 30. doi:  10.1371/journal.pone.0034301.

*** Sarrafchi A, Odhammer AM, Hernandez Salazar LT, Laska M. Olfactory sensitivity for six predator odorants in CD-1 mice, human subjects, and spider monkeys. PLoS One. 2013 Nov 20;8(11):e80621. doi: 10.1371/journal.pone.0080621. eCollection 2013.