Moore book reveals wonders of our sense of smell

Our noses are trying to tell us something — a lot of things, in fact, says Dr. Paul Moore, biology. The problem is that we often aren’t getting the message because, as humans, we don’t process smell the way we do sight and sound. Nevertheless, smells are having a powerful, unconscious influence on us every day.

People may be surprised to learn they have the same number of neurons to receive smell as dogs do, Moore said. “But chemical senses go to our emotional center instead of our intellectual, or thinking center, so we process them differently and often don’t pay proper attention.”

Moore has written a book about the underrated sense of smell. Aimed at a popular audience, “The Hidden Power of Smell: How Chemicals Influence Our Lives and Behavior” reveals the complex and vital role that smell plays in our everyday lives, our cultural understanding and our very bodily functions.

Published this month by Springer International Publishing, “The Hidden Power of Smell” contains illustrations by 2014 BGSU alumna Katie Wilson, an art education major. Its 10 chapters have titles such as “Smells Like Teen Spirit,” “The Cocktail Party of Life,” “Who Are You?” and “The Allure of Sex.”

“From a biological point of view, smell is the first sense,” Moore said. “Every animal communicates through the sense of smell, from the moment of birth. As newborns, our eyes are unfocused, our hearing may be muffled, but we can smell intensely.”

It’s the thing that bonds mothers to infants in all species, enabling an animal mother to pick out her child from among many who may look just the same. Chemical signals can identify us as friend or foe or, in some cases, can be used to mask our true feelings, a strategy used by some spiders when stalking prey.

Smell can sometimes be employed as a sort of Trojan horse. Moore cites the genius of some Ninja-type ants who capture and kill an ant from another nest, then rub their heads on its body to pick up the smell. Disguised by the victim’s scent, they enter its nest and kill the other inhabitants to take over their territory.

When it is not being used aggressively, smell is an important survival tool, not least by signaling spoiled or poisonous foods.

“There are many classes of odors, but the smell of death and decay evokes a certain set of responses, a universal reaction of disgust,” Moore said. “In fact, we have to train ourselves to like the bitter taste because in nature it’s associated with danger.”

It is known that dogs can be trained to detect cancer and other illnesses through smell, but BGSU music faculty member Dr. Mary Natvig can attest to humans’ ability to do the same. The daughter and granddaughter of physicians from rural Wisconsin in the days when doctors made house calls, she well remembers her grandfather’s legendary ability to diagnose his patients’ illnesses by the odor in their homes — a skill her father also possessed. In fact, long after her grandfather was no longer able to make house calls, the local hospital retained him for his diagnostic abilities. Her story is included in the book.

In addition to doctors, “firefighters, food and wine tasters and perfumers train themselves to a small range of chemical smells,” Moore said, and can perceive and identify the most subtle differences.

It turns out that even plants use chemical signals to protect themselves and communicate with one another. Moore noted that oak trees, when attacked by a predatory caterpillar, send out chemical signals through their roots to other oaks in the vicinity that alerts them to produce a toxin to repel the invaders.

While visual and auditory signals must be analyzed and interpreted cognitively, smell, going straight to the emotional center of the brain, produces an instantaneous response, Moore said. “A smell can bring on a flood of memories in which you’re instantly dragged back to a moment in time,” he said. It could be the signature blend of smells from your grandmother’s home, or, negatively, a food aversion associated with a bad memory.

When it comes to choosing a mate, we tend to think of love first as the prime motivator, with money or social status among other considerations. But humans’ choice of mates can also be influenced by smell, perhaps masquerading as love. People are unconsciously drawn by subtle scent cues to potential mates whose blood contains different antigens from their own. This is because more robust offspring result from parents who do not share the same gene types, which helps avoid babies’ receiving two sets of a problematic gene.

The effect in the animal world can be even more dramatic. When a male mouse enters a colony of females, he produces an odor that causes them to ovulate; he can then mate with them and produce a host of offspring. However, if another male then enters the colony, he can exude a hormone that causes the females to spontaneously abort their fetuses, allowing him to mate with them and supplant the first male in the hierarchy.

Women in general are more sensitive to smell, Moore noted, just as they are to taste, which is highly dependent on smell anyway. “Roughly 80 percent of what we perceive in consuming food is smell, not taste,” he said — a phenomenon experienced by anyone who has suffered a bad cold or allergies. Losing the deep connection to the world that smell affords us is a serious blow. Moore includes the example of a woman who became depressed after losing her sense of smell due to allergies following a move to the opposite coast. She regained her ability to smell, along with her happiness, only when she moved back home and her allergies disappeared.

Culture plays a role in how people think of scents, Moore said. Some of it is historic, some influenced by marketing. “In the U.S., we associate the smell of pine with cleanliness. In other places it’s vanilla,” he said. The giant U.S. market in air fresheners may be doing a disservice by dulling people’s sense of smell and thus depriving them of important information.

The book is Moore’s first foray into popular science writing. “I was inspired to write it because I was frustrated by how we undervalue our sense of smell,” he said.

His scholarly research for about the last 30 years has focused on chemical signaling, particularly in crayfish, who communicate through scent. “They use it to signal aggression but also to give and get information,” Moore said. “When one meets another, it can signal ‘Who are you?’ and whether they are male or female, or say ‘I fought you yesterday and I lost, so I’m not a threat,’ or vice versa.”

The many stories and anecdotes in “The Hidden Power of Smell,” combined with the science, provide a compelling case for becoming more aware and respectful of the hidden universe of sensory information available to us right in front of our noses.