Natalie Bennet's review of AROMA inspired me to dust of these old reviews of books that are still available and worth discovering, JACOBSON'S ORGAN and WHY WE LOVE. The latter came out recently in paperback.

You can also read them and discover related titles in my online science book review archive.

Jacobson's Organ and The Remarkable Sense of Smell by Lyall Watson

In every human nose, on either side of the septum about a half-inch above the nostril, are two tiny pits that comprise an organ few people have heard of and even fewer understand. Named for Danish anatomist Ludwig Levin Jacobson who discovered it in 1811, this little-known structure may be the one of most important mediators of our interactions with other people and other living species.

Rich in receptors for large molecules that carry no perceptible odor, the Organ of Jacobson connects to nerves that carry messages directly to the limbic system, the primitive portion of the brain where signals induce emotional, not rational, responses. No wonder the author, Irish naturalist Lyall Watson, calls it the seat of a powerful yet unappreciated sixth sense. "The air is full of messages," he writes, "and we are all born to be subscribers to the Odornet."

This book evokes multi-sensory experiences. Readers become aware not only of the words on the pages but also of their own breathing and of previously unnoticed scents around them — including their own. Their intellect and sexuality are piqued together as they discover the swift and potent effect of boars' breath on receptive sows. Their nostrils flare and then smiles spread across their lips as they read of the unusual ability of male tigers to spray their urine backwards, producing an odor "so strong that the Sanskrit word for tiger is 'vyagra,' ... derived from a verb root meaning to smell."

Though much of the book describes consciously perceived odors, Mr. Watson's skillful selection of details continually keeps readers aware of Jacobson's Organ and its complementary olfactory function. Are there such things as human pheromones, and do we have an organ to detect them? Our folklore and poetry have always said yes, but rational science has only accepted sense organs that respond to stimuli of which we are aware.

The problem with that approach, writes Mr. Watson, is that Jacobson's organ bypasses the conscious mind and targets our emotional centers. He cites research showing electrical responses in Jacobson's Organs to pheromones in skin cells, differing according to the sex of the smeller and the one being smelled. That discovery led to the founding of the Erox Corporation, which manufactures two fragrances, one for each sex.

Mr. Watson ends the book with a full chapter of admitted speculation, including a scientific basis for clairvoyance, reasons to be wary of rhinoplasty, and an olfactory explanation for the tension in step- and foster-families. Yet readers — and reviewers — are disinclined to respond negatively to even the most far-fetched of these claims. Could the publisher have added a secret ingredient to the ink?