Monday, September 22, 2008

Coming Soon to Your Wallet

An entertaining take on scented credit cards.

Tuesday, September 16, 2008

Small Fish, Big Stink

The New York Daily News reported yesterday that local residents are outraged about stinky dead fish. In the town of Howard Beach, located in Queens just west of JFK airport, there’s a canal called the Shellbank Basin. It opens into Jamaica Bay, home to fish known as menhaden (or “bunker” in the local argot). Every so often, predators like bluefish drive a school of menhaden into the canal, where low oxygen content kills many of them. The result—a floating mass of rotting fish and loud complaints from the neighbors.

No doubt it’s an unpleasant situation, but it’s hardly unique.

Bad-smelling fish die-offs are a regular occurrence in some places. The Neawanna River on the Oregon coast is periodically choked with dead anchovies. In the District of Columbia alewives swim up the Potomac River from the Chesapeake Bay to spawn in the Tidal Basin. The females die after laying eggs.  Sea gulls gorge themselves on the sushi and strew the stinky leftovers among the Japanese Cherry Trees.  The timing is bad for tourism: it usually happens only days before the beginning of the Cherry Blossom Festival.

Alewives achieve their olfactory apotheosis in Lake Michigan, where they give Chicago its most notorious malodor. When alewives first entered the Great Lakes in the 1930s they were kept in check by the native lake trout which preyed on them. When lamprey eels began killing the trout, the alewife population soared—by the late 1960s they were about eighty percent of all fish in Lake Michigan. The annual post-spawning die-off grew to epic proportions. The one in 1967 was the biggest and stinkiest of them all: an estimated one million pounds of alewives washed up along the Chicago lakefront. Selective poisoning of the lampreys, and reintroduction of predators like trout and coho salmon, have since reduced the alewife population to ten percent of the lake’s fish. But each spring some alewife carcasses float to shore and begin to stink.

UPDATE 9/16/08, 3:25 p.m.
It looks like it's not just a New York thing.  The NBC-TV affiliate in Hartford reported today that dead menhaden are floating to the surface of the Branford River in Branford, Connecticut, and stinking up the joint. (Branford is on the shoreline of Long Island Sound.) According to Channel 30, state environmental officials attribute the fish-kill to those pesky bluefish driving schools of menhaden up the river into low-oxygen waters.

Monday, September 15, 2008

10,000 Different Smells? Enough Already.

Writing for the UK’s Daily Mail this week, journalist Josh Sims has a piece called “15 Things You Didn’t Know About Men’s Fragrances.” Many of his items are built around numbers—it’s a nice hook, with titles such as “30 Minutes - The Time It Takes for ‘Base Notes’ to Appear,” and “33 Percent of Men’s Perfumes Are Worn by Women.” Good fun and entertaining.

But then he offers this bit: “10,000 - The Number of Different Odours We Can Distinguish.” Here I have to blow the whistle.

Ever since I began working in the psychology of odor perception, I’ve seen references to 10,000 different smells. It shows up everywhere—from fashion magazines to scientific journals. It was even cited by the Nobel Foundation when it awarded the 2004 prize in Physiology or Medicine to Linda Buck and Richard Axel for discovering the olfactory receptor genes. So one can hardly blame Johs Sims for thinking it was a number he could bank on.

But, as I wrote in What the Nose Knows, “Something about it has always bothered me—why such a nice fat round number? Why was there no date of discovery? And, strangest of all, why did nobody take credit for it?”

I decided to discover the source of this mystery number for myself. After a lot of time in the library, and after following innumerable dead ends, I finally found it. Back in 1927, two American chemists—Ernest C. Crocker and Lloyd F. Henderson—were looking for an objective way to classify odors. They came up with a numerical coding system in which any smell could be assigned a four-digit identifier. According to the mathematics of the Crocker-Henderson system, it was theoretically possible to identify 6,561 different smells. Years later, Crocker rounded this up to 10,000, the number everyone has been citing ever since.

The trouble with these numbers—whether 6,561 or 10,000—is that they represent a theoretical upper limit based on a very specific set of starting assumptions, namely four odor standards and nine-point rating scales. These numbers are not based on experimental data. Crocker and Henderson never attempted to count all the different odors that humans can smell. Nor has anyone else as far as I know. And in any case, it turned out that people couldn’t rate smells reliably using four standards and nine-point scales. The system was eventually abandoned.

Don’t get me wrong—I think Ernest Crocker and Lloyd Henderson were innovators and optimists in the best “can do” tradition of American enterprise. But the figure of 10,000 different odors is, from a scientific perspective, utterly worthless. Now that my book is out and the story has been told, it’s time to lay the 10,000 number to rest.

Monday, September 8, 2008

On Old Olympus’ Towering Top

Generations of medical students memorized the names of cranial nerves I through XII with some version of the rhyme, “On Old Olympus’ Towering Top A Finn And German Viewed Some Hops.” The clues lie in the first letter of each word, which matches that of the corresponding nerve: Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, and so on. The olfactory nerve is Cranial Nerve I, hence the name of this blog.

Without ever intending to, I’ve devoted most of my professional lifetime to the study of odor perception and everything that goes with it: from synaesthesia, olfactory memory, mood and emotion, to fragrance chemistry, neuroanatomy, and molecular biology. I've also become knowledgeable about product development, brand management, marketing, corporate behavior and entrepreneurship.

What I love about the sense of smell is the interplay between science and popular culture. I’ve written about this in my book and I’m always finding new and intriguing examples. When I do, I intend to blog about them here on First Nerve.