Tuesday, July 21, 2015

Stepping in It: How Journalists Perpetuate the Myth that Dogs' Sense of Smell is Superior to Our Own

We’ve been hearing a lot about dog noses recently and how they are far more sensitive than ours. Liz Bestic kicked things off with a July 1 story in New Scientist called “The cancer sniffers: Dogs could be the best tool for diagnosis.” She covers some studies showing that dogs are able to sniff out specimens from patients with various types of cancer. An infographic accompanying her story states
“A dog’s sense of smell is between 1000 and 100,000 times more sensitive than that of humans.”
Next up was Rachel Pannett, the Sydney-based Deputy Bureau Chief for The Wall Street Journal in Australia and New Zealand. Her story appeared on the front page of the July 16, 2015 edition: “Forget drugs, these dogs sniff out a different kind of evil weed: Australia tries using spaniels to hunt for invasive plants called orange hawkweed, a.k.a ‘Grim the Collier’.” Pannett’s story includes this line:
A dog’s nose can be over 10,000 times more sensitive than humans, according to academic studies.
Zounds! Those are some impressive numbers. No wonder those dogs can sniff out cancer—their sense of smell is soooo much more sensitive than ours.

But wait. What’s that beeping sound in the distance? Why, it’s the alarm on the FirstNerve Bogosity Meter (hooked up to the battery of a rusty Ford F150 behind the tool shed). It seems there might be something dodgy about these doggy claims.

First off, let’s assume for the sake of argument that all the experimental results are correct and dogs can reliably sniff out a variety of human cancers. What does that prove about the relative sensitivity of dog noses and human noses? The answer is: nothing at all. Relative sensitivity is logically irrelevant to these results. But for some reason, journalists feel compelled to assert that dogs have more sensitive noses than we do. A competitive sniff-off between dogs and humans would address the point directly. It would be nice if a Deputy Bureau Chief or a “health journalist” asked cancer study researchers whether they had, you know, let human panelists evaluate the scent samples the same way the dogs did. Wouldn’t it be interesting if a bunch of orderlies, interns, and maintenance people could sniff out cancer? (Bestic mentions that doctors since Hippocrates have used smell as a diagnostic tool. She doesn’t explain why 21st century physicians have suddenly ceded the game to dogs.)

Hey! Will someone please turn down the alarm on the Bogosity Meter? It’s getting on my nerves.

The next fishy thing about these stories is the beautiful, quote-tastic simplicity of the numbers: dogs are 1,000 or 10,000 or 100,000 thousand times more sensitive than humans. Not 27,000 times more sensitive. Not 1,450 times. But more sensitive by nice fat powers of ten.

Bestic and Pannett are merely the latest journalists to run with these numbers. Here is Mary Bates, PhD, writing on the Animal Minds blog at PsychologyToday.com in 2012 (“Cancer-detecting canines sniff out a diagnosis”):
Canines’ sense of smell is generally 10,000 -100,000 times superior to that of humans.
Stefan Lovgren (“Dogs smell cancer in patients’ breath, study shows,” National Geographic News, 2006) and Peter Tyson (“Dogs’ dazzling sense of smell,” scienceNOW blog at PBS.org, 2012) use the same comparisons.

So where are journalists getting these numbers? Unlike their colleagues, Lovgren and Tyson attribute them to a specific person. Here’s Lovgren:
According to James Walker, director of the Sensory Research Institute at Florida State University in Tallahassee, canines’ sense of smell is generally 10,000 to 100,000 times superior to that of humans.
And here’s Tyson:
Dogs’ sense of smell overpowers our own by orders of magnitude—it’s 10,000 to 100,000 times as acute, scientists say. “Let’s suppose they’re just 10,000 times better,” says James Walker, former director of the Sensory Research Institute at Florida State University, who, with several colleagues, came up with that jaw-dropping estimate during a rigorously designed, oft-cited study.”
Now we’re getting somewhere—the 10,000 to 100,000 claim was made by a smell scientist. [Full disclosure: I met Jim Walker numerous times at the AChemS meetings long ago.] Walker and his colleagues were once active in designing new ways to measure olfactory sensitivity. In 2003, they published a paper in Chemical Senses called “Human odor detectability: new methodology used to determine threshold and variation.” Using their new technique, they estimated a value for human sensitivity to amyl acetate, a chemical that smells like bananas and is something of a standard odor in studies on olfactory thresholds. So far, so good.

In 2006, Walker and colleagues published “Naturalistic quantification of canine olfactory sensitivity” in Applied Animal Behaviour Science. They tested two dogs (a Rottweiler and Standard Schnauzer) for sensitivity to amyl acetate. The threshold value they found was lower than that reported previously by other dog researchers, presumably reflecting the more precise experimental methods used.

In discussing the results, the researchers wrote
Our recent investigation of human odor detectability (Walker et al., 2003) yielded thresholds approximately 10,000- to 100,000-fold higher than those we report here for the dog.
Again, so far, so good. But note: the “10,000- to 100,000-fold higher” statement applies only to amyl acetate (i.e., one specific chemical) and only to two studies (i.e., those coauthored by Walker). Yet Lovgren and Tyson quote Walker with the clear implication that dogs are 10,000 to 100,000 time more sensitive to smells in general. Either Walker did not mention these limitations when he was interviewed by them, or he mentioned the caveat and they chose to ignore it. In any case, journalists are now on notice that they should be cautious in how they quote Walker and/or his 10K/100K claims of canine smell superiority.

Still, there exists a strong presumption that dogs have a sense of smell that is more sensitive than ours in general, i.e., for the vast majority of odors. Surely there are other studies on other odor chemicals that support the claim, no? Enter Matthias Laska, a professor at Linköping University in Sweden. Laska is far and away the current authority of olfactory sensitivity in mammals—he has conducted smell experiments with mice, spider monkeys, squirrel monkeys, pigtail macaques, elephants, and fur seals. At this year’s AChemS meeting in April, Laska gave a talk titled “Busting a myth: humans are not generally less sensitive to odors than nonhuman mammals.” (Abstract here.) I attended his presentation and found it compelling.

Laska put together a data base of all published odor thresholds for humans and nonhuman mammals (17 species tested across a total of 138 odors). This let him compare the relative performance of humans and other species on a chemical-by-chemical basis.
I found that human subjects have lower olfactory detection thresholds, that is, a higher sensitivity with the majority of odorants tested so far compared to most of the nonhuman mammal species tested so far. This includes species traditionally considered to have a highly developed sense of smell such as mice, hedgehogs, shrews, pigs and rabbits. Humans outperform rats with 31 of the 41 odorants tested with both species. Humans even outperform the dog, often considered as the undisputed super-nose of the animal kingdom, with 5 of the 15 odorants tested with both species. Based on these comparisons, and contrary to traditional textbook wisdom, humans are not generally inferior in their olfactory sensitivity compared to nonhuman mammals.
So according to the most recent, most comprehensive review of the topic, humans outperform dogs on 5 of the 15 odorants tested. Does that sound like total, across-the-board, doggy nose superiority to you? No, not really.

After the recent flurry of dog superiority claims, I checked in with Laska by email. He confirms that the canine odor threshold for amyl acetate (-5.94 log ppm) reported in Walker’s 2006 study is the lowest on record. However, he points out that the lowest reported human threshold for amyl acetate in his database is -7.02 log ppm. In other words, when it comes to amyl acetate humans are more sensitive than dogs.

Let me repeat that: According to all the available scientific evidence, humans are more sensitive to amyl acetate than are dogs.

Where does this leave us? With three take-home messages:

#1: James Walker’s narrow claim that dogs are 10,000 to 100,000 times more sensitive to amyl acetate than humans is simply incorrect. The fact is that humans, not dogs, are more sensitive to amyl acetate.

#2: The broader, and much-cited claim that dogs are 10,000 to 100,000 times more sensitive to smells in general is unsubstantiated. The fact is that dogs outperform humans on some but not all of the smells tested to date.

#3: The media ought to take a healthily skeptical approach to claims about the incredible superiority of the canine sense of smell. Some of us have expressed reservations about this before, and have noted that undue deference to the dog nose leads to some dubious outcomes in the criminal justice system. Even assuming that all the studies to date are valid and replicable, the practicality and cost-benefit ratio of cancer detection with sniffer dogs is not that impressive.

P.S. Don’t even bother coming back at me with the claim by one Dr. Lawrence Myers. “Dr. Myers has been quoted as saying dogs can smell a million times better than humans. He says that was a speculative (but possible) number he used in an interview to illustrate a narrow point. The reporter picked up the figure as science and quoted it out of proper context.”

P.P.S. Und danke schön, German dog fans, but don’t bother digging up this old bone from 1953: “The olfactory sensitivity of the dog is 1,000,000 to 100,000,000 times better than humans.” [My translation.] It’s a hand-waving, one-line summary of results, now superseded, that dates back to the dawn of olfactory psychophysics.

The studies discussed here are “Human odor detectability: new methodology used to determine threshold and variation,” by James C. Walker, Sandra B. Hall, Dianne B. Walker, Martin S. Kendal-Reed, Alison F. Hood & Xu-Feng Niu. Chemical Senses 28, 817–826, 2003; “Naturalistic quantification of canine olfactory sensitivity,” by Dianne Beidler Walker, James Cornelius Walker, Peter James Cavnar, Jennifer Leigh Taylor, Duane Howard Pickel, Sandra Biddle Hall & Joseph Carlos Suarez. Applied Animal Behaviour Science 97, 241–254, 2006; and “Über die Riechschärfe des Hundes für Fettsäuren,” by Walter Neuhaus. Zeitschrift für vergleichende Physiologie 35, 527-552, 1953.

Sunday, July 12, 2015

ISDP July 2015: Abandoned Structures and Squatters Edition

It seems like only yesterday, yet is has been a full month since we last gathered the late-breaking accounts of recently deceased individuals whose remains were discovered through their putrescent emanations. Time flies when you are constantly on the move, as we are here in our newly adopted home state of Colorado.

Our June edition was posted from a dilapidated farm building on the eastern plains where we had holed up following our successful #escapefromNJ. But due to some unpleasantness with the Weld County Sheriff’s Department and a notice of illegal occupancy from some dick who thinks that just because his family has owned this property since 1910 it entitles him to shove us and our belongings to the shoulder of a state highway, we had to seek new accommodations.

Well, we were quite successful. Our new digs are next to a stand of shady cottonwoods, out on the Pawnee National Grasslands.

It looks like no one has occupied the structure since about 1948, when the last owner succumbed to a severe case of jake leg. Being on Federal lands and all, we figure it will require a lot more lawyering to evict us anytime soon. Besides, we have a certificate from the Elizabeth Warren Institute of Genealogy showing that we are 1/64th Pawnee. Booyah.

From WBFO 88.7 FM in Buffalo, New York, “Buffalo’s NPR News Station”:
The body of a dismembered woman was found Tuesday night in a house in Niagara Falls. 
[Wait! NPR does dismemberments? Since when?—Ed.] 
The grisly discovery was made around 10:30 p.m. at a vacant home at 1129 Willow Avenue after a 911 call from a neighbor who reported a foul odor. The head, arms, and feet were removed from the deceased woman.
The victim, who police were able to identify, was a 46-year-old local woman. The case has disturbing similarities to the 2012 dismemberment of another local woman.

Then there is this case from Frederiksted, St. Croix, U.S. Virgin Islands
dispatchers received a call of a foul odor emanating from the area of Prince and King Cross Streets, north of the Anglican Church in Frederiksted.
The area turned out to be a building that had collapsed several days before. When authorities cleared away the rubble, they found the body of 56-year-old man who had been squatting in the structure before it caved in.

The body of a 40-year-old man who had been reported missing days earlier was found in an abandoned house in East Wichita, Kansas. However, police were already checking the home when they noticed the foul odor and discovered the body. So, as per many precedents of the Rules Committee, there is no ISDP here. Move along, please.

Car Culture

Workers at a car dealership in Woodland, California, called police to complain about a foul odor coming from the back lot. Officers discovered the body of man in the back of an SUV that was for sale. They are treating the case as a homicide pending a coroner’s report.

The deceased was later identified as a 35-year-old Woodland resident.

Tonya Slaton

The body of Quincy Jamar Davis, missing since 2004 when he disappeared as a seventh-grader, has been found inside a black plastic bag in the trunk of his mother’s car. Forty-four year old Tonya Slaton was pulled over by police in Richmond, Virginia, for driving with expired license plates. During a search of the car, a trooper noticed an odor coming from the bag and opened it, only to find the child’s remains. Astute readers will note that the search was underway before the odor was detected, which means this cannot qualify as a legit ISDP incident. (Our by-laws require that the stench of decay be the factor that leads to the discovery of the deceased.) However, Ms. Slaton’s mobile storage of her son’s remains, and presumably her continuing to drive around town with them in the trunk for over a decade, most definitely earns her a nomination for the 2015 Norman Bates Award™.

Loyal readers will recall our coverage earlier this year of Holden Clark, the 15-year-old from Corpus Christi, Texas. The young man is accused of killing his mother and stuffing her remains into a trash can in the kitchen. He then proceeded to hang around the house which earned him a nod for this year’s Norman Bates Award™. Just to bring you up to date, Clark’s attorney recently asked the court the release him from the Juvenile Detention Center because he had, you know, followed all the rules there for the last six months. For some reason, Judge Tim McCoy denied the lad’s request.

This headline from the Pensacola News Journal—“Man lives months with mom’s corpse on couch”—is enough by itself to earn 60-year-old Michael Eugene Sticken a nomination for the 2015 Norman Bates Award™. Sticken had been living with his mother in Pace, Florida, but since January had deflected attempts by family members to call or visit 81-year-old Joyce Willis. A Santa Rosa County sheriff’s deputy was asked to make a welfare check on the old lady.

Michael Eugene Sticken
When the deputy arrived at the residence he immediately noticed a foul odor. Upon entering the house, he found two couches pushed together with blankets piled on top. Under the blankets, the deputy found a female who was so badly decomposed as to be unrecognizable.
The Medical Examiner estimates that Ms. Willis died one to four months previously.

Sticken, who had been withdrawing his mother’s monthly social security payments from their joint bank account, was charged with grand theft and failure to report a death.

Young People Today

A 15-year-old girl who “smelled a foul odor” followed her nose to discover a dead body near the Stone Mountain apartment complex in DeKalb County, Georgia.

In Ormand Beach, Florida,
A woman told police that she found a man’s body wrapped in plastic shortly before 10 a.m. Friday after she smelled a foul odor inside the home in the Hunter’s Ridge subdivision near State Road 40.
She also saw Garrett Schroeder, 22, walking away from the home. Police obtained an arrest warrant for him. Three days later, Schroeder was found dead, an apparent suicide.

The plastic-wrapped body discovered by the woman who smelled it, turns out to be that of Christian Schroeder, Garrett’s father.
Schroeder had been arrested in 2014 on charges of aggravated battery with a deadly weapon after he allegedly attacked his mother with a hammer. Authorities believe the suspect had a rocky past with both his mother and father.

Apartment Complexes
City of Batavia: 400 Towers residents complain about handling of neighbor's death. 
Lori Kilanowski had tried to get help for a fellow resident who was found dead June 12 at 400 Towers, she says. 
“I said somebody died up there,” she said Wednesday at the East Main Street complex.
And she was right. Always Trust Your Nose™. Management denies that it failed to act expeditiously.

In Rochester, Minnesota,
Police say a 35-year-old woman was found [dead] around 4 p.m. Monday in her apartment after neighbors complained of a foul odor.
And finally, from Dallas, Georgia
Holmes’ body was found in a wooded area last Friday, July 3, by a local resident who was investigating a foul odor. The body was badly decomposed, police said.
Well, th-th-that’s all, folks! See you next month for what promises to be a bumper crop of ISDP as we head into the hottest month of the year.

Sunday, July 5, 2015

The Stench of the Abyss

InfernoCanto XI

[Circle Six: The Heretics]
In su l’estremità d’un’alta ripa
che facevan gran pietre rotte in cerchio,
venimmo sopra più crudele stipa;
e quivi, per l’orribile soperchio
del puzzo che ’l profondo abisso gitta,
ci raccostammo, in dietro, ad un coperchio

d’un grand’ avello, ov’io vidi una scritta
che dicea: ‘Anastasio papa guardo,
lo qual trasse Fotin de la via dritta’.

«Lo nostro scender conviene esser tardo,
sì che s’ausi un poco in prima il senso
al tristo fiato; e poi no i fia riguardo».
We came to the edge of an enormous sink
rimmed by a circle of great broken boulders.
Here we found ghastlier gangs. And here the stink

thrown up by the abyss so overpowered us
that we drew back, cowering behind the wall
of one of the great tombs; and standing thus,

I saw an inscription in the stone, and read:
“I guard Anastasius, once Pope,
he whom Photinus led from the straight road.”

“Before we travel on to that blind pit
we must delay until our sense grows used
to its foul breath, and then we will not mind it,”

my Master said.

[Translation by John Ciardi]

A fine example of olfactory literature: the stench of the pit is simultaneously literal and figurative. Virgil’s advice to Dante to pause while their noses adapt draws on a keenly observed bit of odor perception; it also provides a dramatic interlude for him to explain the next levels of the damned. The presence in Hell of Pope Anastasius is nice reminder that popes too can be led astray.

Friday, July 3, 2015

Loving it in Colorado: July 4th Edition

I keep finding new reasons to love my new home state.

These are all legal in Colorado as long as you are 16 years old:
Cylindrical and cone fountain, ground spinner, torch and colored fire, dipped stick and sparkler, snake and glow worm, trick noisemaker and certain other novelties.
They are all banned in New Jersey. Even if you are an adult.

The Upside of BO

Top five things I miss about Laura. [ . . . ]

Three: I miss her smell, and the way she tastes. It’s a mystery of human chemistry and I don’t understand it, some people, as far as their senses are concerned, just feel like home.
Rob (John Cusak) in High Fidelity