The nose knows

The first few years my wife and I were married, we had a dog named Doolin.

At least I think Doolin was a dog.  The story is that she was born to the unholy union between a border collie and a bluetick coonhound, but there's credible evidence she was an alien infiltrator from the planet K-9, sent to study humans by pretending to be a humble house pet.  My observations suggested that she was far smarter than humans but had only recently mastered pretending to be a dog.  She is, far and away, the weirdest dog I've ever met, and I've had dogs pretty much my whole life.  She figured out how to unlatch our gates (and let herself out) by watching us; we ultimately had to put carabiners on the latches to stop her from going on walkies by herself.  She valiantly attempted to herd our four cats, an effort that was ultimately unsuccessful.  Of her many odd habits, one of the funniest was that she was never without her favorite toy, a plush jack that she carried around in her mouth -- always pointing the same way.  (We tested this by taking it from her and sticking it in her mouth the other way 'round.  She dropped it, looked at us as if we'd lost our minds, and picked it up from the other direction.)

Doolin, with her jack toy sticking out of the right side of her mouth, as it obviously should be

One of Doolin's most curious traits was an extraordinary sensitivity to us, particularly to Carol.  She seemed to watch us continuously for cues about what was going on, and sensed when one of us was upset or feeling unwell.  Most strikingly, Doolin always knew when Carol was about to get a migraine.  Starting about a half-hour before the symptoms began, Doolin followed Carol around like her shadow, and if Carol sat down, Doolin smushed herself right up against her.  It got to be that Carol knew when to prep for a migraine once she saw Doolin acting weird (well, weirder than usual, which was admittedly a pretty high bar).

I used to think that people claiming their dogs had a second sense about how they (the owners) were feeling was an example of people anthropomorphizing, or at the very least, exaggerating their pets' intelligence and emotional sensitivity.  Until I had lived for a while with Doolin.

After that, a lot of the stories I'd heard began to seem a good bit more plausible.

Just this week, some research supported the contention with hard evidence.  A team of scientists in Belfast studied the responses of four dogs to breath and sweat samples from thirty-six volunteers, before and after doing a stressful exercise -- counting backwards from 9,000 by intervals of 17, without using calculators or pen and paper.  The researchers laid it on thick, telling the participants that it was very important to the study to do the counting exercise quickly and accurately.  A wrong answer got a shouted "No!", followed by being told the most recent correct response and an instruction to pick up from there.  For most of us, this would be a pretty high-stress activity, and would cause stress hormones (like cortisol and epinephrine) to pour into our bloodstreams.

And the breakdown products of those chemicals end up in our breath, sweat, and urine.  What's remarkable is that the four dogs, which had been conditioned to be able to discern between samples containing those breakdown products from ones which did not, correctly distinguished the post-stress breath and sweat samples from the pre-stress ones 93% of the time.

I know that our current dogs are pretty sensitive as well (although nowhere near the level of acuity that Doolin had).  Cleo, our Shiba Inu rescue, is really keyed in to me especially.  I had a couple of seriously high stress things happen in the last couple of months, and whenever I was really in freak-out mode, Cleo followed me around with a very worried expression on her face.  Her curly tail is like a barometer; the tighter the curl, the happier she is.  And when I was struggling, her tail was sagging.  Clearly an unhappy dog.

Cleo the Wonder Floof

So I guess all this stuff isn't our imagination.  Dogs really do sense our emotional states, not by some kind of canine telepathy, but because of plain old biochemistry coupled with an extraordinary sense of smell.

Although I wonder about Doolin.  I still think she was an alien spy, and was relaying information about us back to the Mother Ship.  Maybe the jack toy was some kind of transmitter, I dunno.

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The smell of friendship

A topic I covered in my intro to biology classes was the phenomenon of pheromones.

A pheromone is a chemical secreted by one individual that causes a behavioral change in another member of the same species.  There's a great variety -- sex pheromones (which causes the behavior you see in male dogs when a female dog goes into heat), alarm pheromones (such as the "attack" chemical released by killer bees that causes swarming), territorial pheromones (such as urine marking in wolves), and so on.  They're biochemical signals; much the way hormones signal between organs, pheromones signal between organisms.

This inevitably led to the question, "Do humans have pheromones?"  The answer is, "Probably, but it's hard to demonstrate conclusively."  Certainly, the "pheromonal" perfumes and colognes you've probably seen ads for are ripoffs; there is no evidence that there's anything you could add to a perfume that would act as an aphrodisiac.  (For some reason, I've mostly seen ads for this stuff in science magazines.  Maybe they think we nerds need all the help we can get in the romance department, I dunno.)

One of my AP Biology students years ago got interested in the topic of attractant pheromones, and designed a clever experiment to see if he could detect an effect in humans.  He had a bunch of volunteers agree to the following protocol: (1) shower first thing in the morning; (2) use odorless soap, shampoo, and deodorant, and don't put on any scented products; (3) don't eat any food that could change your body odor, such as garlic, curry, or asparagus; and (4) wear a plain white t-shirt (provided by the researcher) for an entire day, then seal it in a ziplock bag at the end of the day.  He then took the collected t-shirts (I think there were about twenty in all) and got a bunch of students to smell them, and rank them best-to-worst for odor.

[Image licensed under the Creative Commons Lateiner, T-shirt-2, CC BY-SA 3.0]

The results were pretty interesting.  There was a tendency for people to rank higher t-shirts that had been worn by volunteers of their preferred gender.  (There weren't any bisexuals in the test sample; maybe we think everyone smells good, I dunno.)  The most interesting part was that between the t-shirt wearing group and the t-shirt smelling group, there were a couple of pairs of siblings -- and they ranked their siblings as smelling terrible!

Curious results, which I was immediately reminded of when I stumbled on some research out of the Weizmann Institute of Science in Israel which showed there might be a pheromonal aspect not only of sexual attraction, but of friendship.

The procedure they followed was remarkably similar to my student's, if considerably more rigorous and technical.  They recruited twenty pairs of people who reported that they were friends, and further, had "clicked immediately" -- a phenomenon I think we can all relate to.  (It's equally common to meet someone you dislike immediately -- but that'd have been a lot harder to study.)  They then did a similar t-shirt wearing protocol, but at the end of the day, instead of having someone smell it, they used an electronic volatile chemical analyzer to determine what odor-carrying substances there might be in the shirts.

What they found was that the chemistry of the sweat left behind in the t-shirts was remarkably similar between people who were friends.  Further -- and even wilder -- they then had the volunteers pair up with same-sex strangers from the research group, eventually testing all possible same-sex pairings, and had them stand in close proximity for two minutes (in silence).  They then were asked to rank the person from 1 to 100 in terms of how comfortable they were, whether they felt a connection, and whether they'd be interested in meeting the person again.

Across the board, the more similar the pair's sweat chemistry, the higher the rankings were.  "The finding that it could predict clicking by body odor similarity alone—this was really cool," said study co-author Inval Ravreby.  "We were really excited to find this."

The researchers did admit that the effect was small (although statistically significant) and there was a lot of overlap in the data, but the fact that there's a trend at all is pretty amazing.  Human behavior is complex and multifaceted, and it's amazing how much of it is due to subliminal cues.  Despite our generally high opinions of our species, we're still animals -- and we interact with each other not only in human-specific ways but in the more instinctual ways other animals use.

Now, I'm not suggesting that you should try to find friends by walking up and sniffing people.  But maybe that feeling of an instant connection we sometimes have is more due to our sense of smell than it is any kind of cognitive assessment.

Think of that the next time you're having lunch with your best friend.

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The scent of memory

When I was about nine years old, I went to live with my paternal grandmother for a year.

Ostensibly the reason was that my parents were in the process of building a house, and where they were living -- a room in my maternal grandfather's house -- there wasn't space for a kid.  My grandmother, on the other hand, lived in a rambling old house with tons of space.  Plus, I idolized my grandma, and had a rather fractious relationship with my parents, so the move resolved several problems simultaneously.

While living with my grandma, my bedroom was in the attic.  Don't think of a cramped, dark space; it was wide open, with dormer windows and lots of separate "rooms" with various nooks and crannies and alcoves and places to explore.  Got a little hot in the summer -- this was southern Louisiana, and there were lots of fans but no air conditioning except a single window-mounted unit down in the living room -- but it was a splendid retreat for a kid who was already a bit of a loner.

Because of the heat, I often slept with the windows open, and one of the two things that will always bring back memories of that year is the sound of church bells in the distance.  My grandma's house was a couple of blocks from Sacred Heart Catholic Church, and the bells ringing in the evening reminds me of those quiet nights in the attic room.

The other, and stronger, association is the smell of old books.

My grandma loved books.  The attic walls were lined with shelves, and filled with what looked to my young eyes like thousands of books, from old cloth-bound textbooks to paperback novels, and everything in between.  The dusty, dry smell of old books brings me back instantaneously; I can almost see the book sitting in my lap as I sat cross-legged on the attic floor, feel texture of the brittle, yellowed pages and the worn cover.  The memories are vivid, detailed, and immediate.

[Image licensed under the Creative Commons Tom Murphy VII, Old book bindings, CC BY-SA 3.0]

I've always wondered why smells can evoke such powerful memories.  It's a common response, but despite this, the underlying mechanism has remained elusive.  But now a study out of Northwestern University, published this week in Progress in Neurobiology, has shed some light on the relationship between olfaction and memory -- and found that it results from an underlying structural feature of the human brain.

The team, led by neuroscientist Guangyu Zhou, studied the connections between the olfactory centers and other parts of the brain, and also looked at activity levels using fMRI technology.  They found something fascinating -- that the olfactory centers have a higher degree of connectivity with the hippocampus (one of our main memory centers) than any other sense, and the activity level in those connections oscillates to match the rate of our breathing.

"During evolution, humans experienced a profound expansion of the neocortex that re-organized access to memory networks," said study co-author Christina Zelano, in an interview with Science Daily.  "Vision, hearing and touch all re-routed in the brain as the neocortex expanded, connecting with the hippocampus through an intermediary -- association cortex -- rather than directly.  Our data suggests olfaction did not undergo this re-routing, and instead retained direct access to the hippocampus."

It does make me wonder a bit about my own case, though, because after decades of sinus problems, my sense of smell is pretty lousy.  It's not gone completely, but I certainly don't have the sensitive nose that many have.  (Which has a variety of downsides, including explaining why I was assigned to clean up when our septic tank backed up, and also give our dogs baths the time they got skunked at five AM.)  Now, there's the additional complication of COVID-19 infection wiping out people's senses of smell entirely.  "Loss of the sense of smell is underestimated in its impact," Zelano said.  "It has profound negative effects of quality of life, and many people underestimate that until they experience it.  Smell loss is highly correlated with depression and poor quality of life...  Most people who lose their smell to COVID regain it, but the time frame varies widely, and some have had what appears to be permanent loss.  Understanding smell loss, in turn, requires research into the basic neural operations of this under-studied sensory system."

I'm a little dubious that my poor sense of smell has anything to do with my tendency toward depression, but that they correlate in my case is at least interesting.  It's reassuring that I still do have memories triggered by smells, so even if I might not be having the full experience of the sense of smell, that part of the system still seems to be working just fine.

Especially the smell of old books and memories of living with my grandmother.  That one is intact and fresh, and (fortunately) a very positive association.  Add it to some sounds -- church bells, the rhythmic drone of an oscillating fan, the song of whippoorwills at night -- and I can close my eyes and for a moment, be nine years old again.

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I've always been in awe of cryptographers.  I love puzzles, but code decipherment has seemed to me to be a little like magic.  I've read about such feats as the breaking of the "Enigma" code during World War II by a team led by British computer scientist Alan Turing, and the stunning decipherment of Linear B -- a writing system for which (at first) we knew neither the sound-to-symbol correspondence nor even the language it represented -- by Alice Kober and Michael Ventris.

My reaction each time has been, "I am not nearly smart enough to figure something like this out."

Possibly because it's so unfathomable to me, I've been fascinated with tales of codebreaking ever since I can remember.  This is why I was thrilled to read Simon Singh's The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography, which describes some of the most amazing examples of people's attempts to design codes that were uncrackable -- and the ones who were able to crack them.

If you're at all interested in the science of covert communications, or just like to read about fascinating achievements by incredibly talented people, you definitely need to read The Code Book.  Even after I finished it, I still know I'm not smart enough to decipher complex codes, but it sure is fun to read about how others have accomplished it.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

The smell of time passing

We once owned a very peculiar border collie named Doolin.  Although from what I've heard, saying "very peculiar" in the same breath as "border collie" is kind of redundant.  The breed has a reputation for being extremely intelligent, hyperactive, job-oriented, and more than a little neurotic, and Doolin fit the bill in all respects.

As far as the "intelligent" part, she's the dog who learned to open the slide bolts on our fence by watching us do it only two or three times.  I wouldn't have believed it unless I'd seen it with my own eyes.  She also took her job very seriously, and by "job" I mean "life."  She had a passion for catching frisbees, but I always got the impression that it wasn't because it was fun.  It was because the Russian judge had only given her a 9.4 on the previous catch and she was determined to improve her score.

There were ways in which her intelligence was almost eerie at times.  I was away from home one time and called Carol to say hi, and apparently Doolin looked at her with question marks in her eyes.  Carol said, "Doolin, it's Daddy!"  Doolin responded by becoming extremely excited and running around the house looking in all of the likely spots -- my office, the recliner, the workshop -- as well as some somewhat less likely places like under the bed.  When the search was unsuccessful, apparently she seemed extremely worried for the rest of the evening.

Not that this was all that different from her usual expression.

One thing that always puzzled us, though, was her ability to sense when we were about to get home.  Doolin would routinely go to the door and stand there on guard before Carol's car pulled into the driveway.  She did the same thing, I heard, when I was about to arrive.  In each case, there was no obvious cue that she could have relied on; we live on a fairly well-traveled stretch of rural highway and even if she heard our cars in the distance, I can't imagine they sound that different from any of the other hundreds of cars that pass by daily.  And my arrival time, especially, varied considerably from day to day, because of after-school commitments.  How, then, did she figure out we were about to get home -- or was it just dart-thrower's bias again, and we were noticing the times she got it right and ignoring all the times she didn't?

According to Alexandra Horowitz, a professor of psychology at Barnard University, there's actually something to this observation.  There are hundreds of anecdotal accounts of the same kind of behavior, enough that (although there hasn't been much in the way of a systematic study) there's almost certainly a reason behind it other than chance.  Horowitz considered the well-documented ability of dogs to follow a scent trail the right direction by sensing where the signal was weakest -- presumably the oldest part of the trail -- and heading toward where it was stronger.  The difference in intensity is minuscule, especially given that to go the right direction the dog can't directly compare the scent right here to the scent a half a kilometer away, but has to compare the scent here to the scent a couple of meters away.

What Horowitz wondered is if dogs are using scent intensity as a kind of clock -- the diminishment of a person's scent signal after they leave the house gives the dog a way of knowing how much time has elapsed.  This makes more sense than any other explanation I've heard, which include (no lie) that dogs are psychic and are telepathically sensing your approach.  Biological clocks of all kinds are only now being investigated and understood, including how they are entrained -- how the internal state is aligned to external cues.  (The most obvious examples of entrainment are the alignment of our sleep cycle to light/dark fluctuations, and seasonal behaviors in other animals like hibernation and migration in response to cues like decreasing day length.)

So it's possible that dogs are entraining this bit of their behavior using their phenomenally sensitive noses.  It'll be interesting to see what Horowitz does with her hypothesis; it's certainly worth testing.  Now, I need to wrap this up because Guinness's biological clock just went off and told him it was time to play ball.  Of course, that happens about fifty times a day, so there may not be anything particularly surprising there.

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This week's Skeptophilia book of the week is brand new; Brian Clegg's wonderful Dark Matter and Dark Energy: The Hidden 95% of the Universe.  In this book, Clegg outlines "the biggest puzzle science has ever faced" -- the evidence for the substances that provide the majority of the gravitational force holding the nearby universe together, while simultaneously making the universe as a whole fly apart -- and which has (thus far) completely resisted all attempts to ascertain its nature.

Clegg also gives us some of the cutting-edge explanations physicists are now proposing, and the experiments that are being done to test them.  The science is sure to change quickly -- every week we seem to hear about new data providing information on the dark 95% of what's around us -- but if you want the most recently-crafted lens on the subject, this is it.

[Note: if you purchase this book from the image/link below, part of the proceeds goes to support Skeptophilia!]