Avery Gilbert has a long track record in the field of smell psychology. His research papers have been published in renowned academic journals since the 1980s, and he has been a consultant to many large firms in the fragrance industry. What the Nose Knows is his first book, and deals with the psychology of odor perception. Piet Vroon and Rachel Herz have written very accessible books on this subject, but their work was primarily focused on the relation between olfaction, emotion and behavior. Gilbert's main mission is a different one: to challenge the assumption that the human nose is somehow inferior to that of other species. "Dogs have great noses," he writes in the chapter on olfactory prodigies, "but it's time to stop the trash talk and give ourselves more credit" (p.63). His message is simple: there's nothing wrong with our nose, we're just not very good at using it.

Since the days of Charles Darwin (1809-1882) and Havelock Ellis (1859-1939), the notion that humans have a poor sense of smell has been more or less taken for granted. Scientists agreed that olfaction had lost its importance to humans from an evolutionary perspective, and that it was barely of use to modern man. In recent years, however, neurobiologists and sensory physiologists have gained better insights into the inner mechanisms of our nose, and have come to the conclusion that our odor sensitivity is actually similar to that of apes. This sensitivity does not depend on the number of olfactory nerve cells or odor receptors in our nose, nor on its internal surface area — it's how the information is processed by the brain.

The same is true for comparative smell abilities between people. Perfumers, for instance, don't have better noses than the average person: they simply make better use of the same sensory information. They do so by relying on their cognitive skills — being able to discern and name fragrances is not a matter of pure nose-sensitivity, but of training. And thanks to CT-scan technology, that difference can actually be rendered visually. In sniffing experiments conducted with groups of smell experts and non-experts, individuals from the former group showed heightened activity in the frontal lobe of the brain, which is involved in cognitive judgments. By contrast, most activity among the non-experts took place in primary sensory areas and zones of the brain associated with emotional response. Another interesting difference between professionals and amateurs is in their sniffing technique. Perfumers tend to favor short sniffs; when non-experts are asked to identify a scent on a paper blotter, they are more inclined to take it all in at once. What they probably don't know is that long sniffs actually dull the nose.

Sensory researchers have just begun to understand the psychological interplay between smell and taste, and What the Nose Knows is one of the few pop-science books to address this subject in a clear, accessible manner. While I believe that Gilbert cuts too many corners when he dismisses anthropological and sociological insights into the culture of taste, there is indeed more biological evidence today to support new approaches to cultural differences between ethnicities. Don’t expect too many scientific details here: it’s all explained by means of practical examples.

As much as I enjoyed learning about the psychology and biology of smell, I couldn’t help frowning at the author's tendency to comment on things he clearly knows very little about. In the chapter on Smell Museums, for instance, he describes the Osmothèque in Versailles as a seemingly boring place to visit:

There are more than 1,400 perfumes in the Osmothèque's collection, including 500 that are no longer manufactured. Despite having worked in the industry, I find it hard to get excited about visiting a perfume museum–how many little bottles can one stand to look at? (take one down, pass it around, 1,399 bottles of scent on the wall...) (p.213)

Being opinionated is fine, as long as you know what you’re talking about: the Osmothèque doesn’t put its collection on display, it’s a place where you use your nose. And while we’re at it: dismissing people’s work by means of ridicule (likening olfactory art to "junior-high-school pranks") is often a proof of weakness; personally, it’s something that really puts me off. I found more examples of character bashing than are worth repeating here.

In short, I can’t help having mixed feelings about this book. It’s a mine of information, but I could do with a less polemical tone. The author’s criticisms are often unsubstantiated, and add nothing to our understanding of smell. So +1 for the original and refreshing content, and -1 for trying to be witty at the expense of others.

Avery Gilbert has published research articles in Chemical Senses, the American Journal of Psychology, the Journal of Applied Social Psychology, Physiology & Behavior, and Nature Neuroscience. He also wrote the Compendium of Olfactory Research (Kendall/Hunt Publishing, 1995).

What the Nose Knows: The Science of Scent in Everyday Life
New York: Crown Publishing Group (2008)
Hardcover, 304 p.