Thursday, July 30, 2009

Crowded House

Her name was Janet, and she had impossibly long, brown hair. Cute as all get-out, and smart to boot: she was one of the pack of new graduate students that year at my biochemistry and biophysics program [1]. More importantly, she seemed possibly interested in me — so I asked her out.

That Friday night, I came by her lab — she was doing a rotation with the biophysics group, a cool subspecialty in which people used x-rays to create patterns of dots that computers helped them decode into the shapes and structures of protein molecules [2] — to pick her up. The plan was dinner, maybe a coffee afterward.

But a lab mate of hers invited himself along.

“I can drive,” he said. I can’t remember whether he was a grad student or a postdoctoral fellow, only that he was older than both of us; but since he had the car, I’m thinking postdoc.

I was pissed off. I was also seriously uncertain of the terrain: was he truly trying to horn in? Did anybody have that kind of gall? Or cluelessness? Or had she set it up, to “de-date” the situation? She certainly hadn’t said she didn’t want him along, which didn’t bode well for my prospects. Still, as a matter of philosophy, my ire centered on this guy [3] — competition, OK; but I draw the line at interference.

So we have our “three’s a crowd” date, with increasing comprehension that I wasn’t going to get anywhere here. But lacking a graceful way of bowing out early, I had to follow through, as if everything were cool, with the whole God-damned dinner. I had my pride [4].

Finally, we’re done; we took her home first. I can’t remember why — I may have left my bike there — but I asked him to drop me off back at the lab. He pulls up to the building, and as I open the door and step out, I allow one crack in my “it’s all good” demeanor of the evening [5].

I asked, “Aren’t you going to walk me to the door?”

He turned away for a moment, couldn’t look me in the eye; and for the first time that evening, I found something to like about the guy — at least he had a sense of shame.

As crowded as that date was, it was considerably less so than the vomeronasal organ is turning out to be. This “pheromone sensor” is sometimes in the roof of the mouth, sometimes in the nasal cavity of vertebrates; but it’s absent in humans and great apes.

In the beginning, the concept of the VNO, also known as the Jacobson’s organ, was simple.
We already knew — because we had one — that the olfactory organ conveyed a sense of conscious smell, a flexible and rapid sensor for whatever chemical cues the environment cared to throw at us, which we then could use to craft a flexible, highly situation-specific, and even individualized response.

The VNO, on the other hand, was supposed to be the sensor for a kind of molecular secret code — a species-specific series of chemical communications that were far more specialized, and which elicited hormonal and reflexive actions that didn’t require conscious sensation of the signal.
This picture developed from the situation in insects, in which these chemical signals, called pheromones, were first discovered and studied. One insect creates a pheromone, another member of its species receives it, and that reception causes a characteristic response — whether to court and mate, show aggression, horde up, whatever [6]. Same pheromone, same response, every time.

Mother Nature, though, finds human beings’ need to classify to be utterly and hopelessly quaint. From the beginning, scientists warned us that it might not be that simple in higher organisms. They were right.

For one thing, and I’ll repeat myself here, mammals don’t do anything for just one reason — pheromone signals seem to enter a kind of voting process that takes in a lot of input and tries to create the best possible response. For another, when the lab geeks started picking apart the receptor proteins that served as the chemical sensors of the system, they rapidly found a diversity that hinted at a much more complicated situation.

The first “pheromone receptors,” it turned out, could be split into two families; interestingly, one of them is predominant in one part of the VNO, the other family in the other part. One immediate possibility was that the two parts of the organ essentially fractionated the pheromone molecules, with one set of sensors responding to one type, maybe those that volatilized into the air efficiently, while the other responded to those that didn’t volatilize well and had to enter the organ in a water solution or other liquid form. Without more to go on, a number of other possibilities fit the bill as well.

Then came the news that the VNO also contained receptors that, for all the world, looked like the ones in the olfactory organ. Was the VNO contributing to the conscious sense of smell? Or were the olfactory receptors in the organ allowing molecules that normally acted as conscious odorants convey a reflexive, pheromone-type signal as well? Investigators also discovered a fourth family of receptors, the trace amine-associated receptors, which sense volatile amines — a toxic family of molecules that contribute to the smells of decomposition, old fish, ammonia, and urine, among others. Maybe conveying reflexive aversion to toxins?

As if four weren’t enough of a crowd, today’s paper, from Mssr. St√©phane Rivi√®re at the University of Geneva and buds, reports the discovery of yet another receptor family in the VNO: formyl peptide receptor-like proteins.

Formyl peptide receptors play a very interesting role elsewhere in the body. They help guide white blood cells to the site of an infection, using chemicals associated with pathogens and tissue damage as the cue. The City of Peace Posse tested that idea out, and found out that the genes for these VNO receptors were able to convey the ability to respond to these cues to nerve cells and that the VNO tissues themselves are sensitive to them.

The connections between smell and immunity, once suggested by Lewis Thomas as the scientific equivalent of a “spitball” idea, are getting harder and harder to ignore. Thomas’ pure concept, that the body may have co-opted the immune system to create a sense of smell (or, more likely, the other way around) mostly isn’t true; not only are most of the molecular actors in immunity and smell different, but they generally are different types of molecules with very different mechanisms [7].

Still, the parallels are striking. As we better understand olfactory receptors, they seem less the pat, lock-and-key, one-odorant/one-receptor, enzyme-like sensors we might have expected (though the “original” VNO receptors are, for a number of reasons, exactly that kind of beast) and more like a cloud of molecular recognition hovering in wait of the next odorant, old or novel, to come along. No one receptor “belongs” to, say, the acetic acid molecule that gives vinegar much of its smell; rather, all share varying responsibility for the acid, with a small number vastly better than others. Dogs’ larger repertoire of receptors than humans’ may help give the former a more acute sense of smell not because it detect more odorants per se, but because it’s got more overlapping ability to sense the same potential swarm of odorants, and so tends to do the same job with more sensitivity. That sounds a lot less like enzymes and a lot more like antibodies, the immune system’s way of doing a similar job.

The discovery of the formyl peptide receptors in the VNO immediately suggests two different but very important possible new roles for the organ.

Rodents (the study was in mice) are good at detecting and declining tainted food; rats are legendary in their ability to evade attempts to poison them. The formyl peptide receptors in the VNO could be playing an active role in subverting the animal’s appetite when food is dangerous (along with the trace amine-associated receptors, see above). On the other hand, the chemicals that these receptors detect can be found in a number of secretions, including urine: this may be a system for identifying infected animals of your own species, so you can avoid them.

Which brings us, again, to dogs. Any owner of a pack of them has probably seen how, when one is sick or somehow “not right,” the others may, shattering our boy-scouts-in-fur-coats anthropomorphization, gang up on it and harass it. Well, it now seems very possible that setting up an antagonistic stance toward a sick pack mate is a role of the VNO [8]. Along those same lines, this could be the receptor responsible for the amazing ability of dogs to detect cancerous tissues in humans — an ability whose proponents tend to forget hasn’t been proved to be any more accurate or cost-effective than standard diagnostic methods, but which nevertheless seems real.

’Course, the “all of the above” and “none of the above” possibilities remain in play. The VNO began its conceptual life as a pure mystery; in the absence of data, some folks attributed to it an almost supernatural character. The reality, now that we have the data, is a bit more prosaic, but no less mysterious, and in some ways far more majestic in scope: we have only begun to understand the large number of important functions that this organ plays in social interactions, speciation, and survival.

The naked ape, also, stands awkwardly in the room: we and our close relatives don’t appear to have a VNO, but we do have VNO-like receptors in our olfactory organs. Are any or all of the above playing roles in our unconscious behaviors?

Stay tuned. Sometimes, a crowded house is a good thing.

[1] Long before th’ better half entered the scene. Not that I'm worried about frying pans.
[2] On a topical note, one project they were working on at the time was an ongoing study of the hemagglutinin molecule, the grappling hook that the flu virus uses to gain entry into human cells.
[3] Lest you think I was attributing the worst intent to a well-intentioned but clumsy attempt to cover for a friend who was too timid to say “no,” he did wind up dating her afterward — so the vibe I was getting, that he wasn’t being altruistic, had merit.
[4] Married for 17 years as of last month, I have no further use for pride.
[5] OK, it’s just possible that I was glowering throughout the evening. I attempted the closest I could manage to cool, anyway.
[6] A little more complicated than that, because classically there were “releasing” pheromones, which cause responses, and “primer” pheromones, which set you up for later responses — in the current Wikipedia article, that list has grown to 10 types, plus an “other” category. But the classic view was it was always the same response, and required no more consciousness than is available to a fly.
[7] One important exception: the same proteins that help identify fragments of invading pathogens may also help cherry-pick the odorants that make up our individual body odors.
[8] Again, nothing for just one reason — doubtless visual and behavioral clues play a role as well.

Friday, July 24, 2009

Now On Sale!

I’m extremely pleased to report that Triangulation: Dark Glass, featuring my horror science fiction short story “Imaginal Friend,” is now on sale at lulu.com.

“Imaginal Friend” is about a group of colonists on an extinct alien world finding out that its former inhabitants don’t like trespassers — and can do something about it, a thousand years after destroying themselves.

Triangulation is the latest of a series of similarly named anthologies put out by PARSEC, Pittsburgh’s literary speculative fiction fan club. As such it’s been a bit of a sleeper in the past — no offense to previous editors, it was always good. But editor Pete Butler and crew have, in the last couple of years, kicked it up to a new league, putting it on the map nationally. I’m looking forward to reading the other stories; I’m also looking forward to the publication party tonight at Confluence, PARSEC’s annual convention.

Truth be told — I want to say this diplomatically — they did well enough that this particular rat wanted to jump onto the ship, and submitted for the first time this year. Can’t tell you how delighted I was that they took “Imaginal Friend,” which is one of my own favorites.

Look for my regular post — on the mysterious vomeronasal organ, and a newly discovered function for it — in the next couple of days. And if you’re anywhere near the Pittsburgh area, consider coming out to Confluence; I’ll see yinz there!

Sunday, July 19, 2009

Oops

A couple of days into the search, things were not looking so good for our subject.

For one thing, there was his physical condition. Diabetes, a kidney transplant, and what the family described as “near-blindness” all argued against him getting very far or surviving very long from where and when he’d mired his quad [1].

For another, we had the results of our efforts to date — or lack of results. We’d plastered the immediate area around that damned quad, with several dog teams and grid teams sequentially covering the same ground. I believe I took one of the last of these tasks — I think it was a hasty that walked us past the ATV, though it’s been a while and may just have been one of those “start at the quad and spiral outward” deals. On this task I was the sidekick for my first SAR partner and ever-reliable anchor, Lilly, and a Civil Air Patrol cadet who’d already demonstrated himself to be a sharp navigator and all-around handy fellow [2].

Lilly showed some interest immediately upon encountering the ATV — but that didn’t mean much to me, as so many people had already covered the area, and Lilly was not “scent-discriminating,” identifying the scent of a specific person. She searched for all human scent. I was marginally more interested when she put her nose down, trailing along the dirt road into and through a clearing up ahead, where the jeep trail ended in a T intersection.

Again, I wasn’t sure what to make of it — so many people had been through the area. Still, it wasn’t impossible that it could be our guy Lilly was following, so I tried to keep an open mind.

Something caught my walker’s eye; he paced into the intersection, knelt down — and called me over.

Lying on the ground was a Virginia Slims butt.

Now, middle-aged, male, western Pennsylvania kidney recipients don’t smoke Slims …

“The daughter,” I said aloud.

We’d been less than thrilled by the family’s insistence on going out on their ATVs on a private search the previous night — both because untrained searchers can inadvertently destroy evidence and otherwise interfere with the organized search effort and, frankly, because the noise had kept us from sleeping well. In particular I’d been peeved by the incident command staff’s inability to put their foot down and stop the freelancing — though, with a heck of a lot more experience under my belt and without a young man’s impatience, today I understand why they just couldn’t do it.

Be that as it was, I realized right away how profound a scent-contamination problem we had surrounding that quad — and how unlikely it was that we had anything left to discover in the immediate area. I told the debriefing officer as much; while I have no doubt that my report didn’t carry any greater weight than anybody else’s, it is a fact that, soon after, the plans section folks started writing up tasks farther away from the ATV — on the third of these, a grid team found this nearly crippled, diabetic, blind subject over a mile away, awaiting help next to the creek that had kept him hydrated while we were looking for him [3].

The guy walked himself out.

When I tell this story — as, in fact, with a lot of SAR war stories having to do with contaminating scent — I know that it automatically begs a question: if it’s possible to ask a dog to search for a specific person’s scent, why would you not do that every time?

There are a few reasons, actually. For one thing, uncontaminated “scent articles” — things that the subject has recently worn, carried, sat upon, touched, etc. — are harder to come up with than you may think. Generally everybody in the family has handled it before you get hold of it — remember, the daughter’s contaminating scent was an issue here. And that’s if you’re lucky, and the entire police and fire departments haven’t passed it among one another. Good scent-discriminating-dog handlers have some tricks, and some training background, that helps them deal with a small amount of contamination (at least, if they know about it); but you get to a point where you’re essentially searching for all human scent anyway.

For another reason, an airscent dog doesn’t need to scent discriminate. If you’re following a scent trail on the ground, you’re inevitably going to encounter other trails, and you need to stay on the right one. But if you’re searching an area in the hope of encountering the wind-borne scent coming off a person at that moment, you can just follow the scent to its source and, if it isn’t your guy, you’ve at least got someone you can ask: “Have you seen him?” Usually, all you’ve lost is a few minutes [4].

Ultimately, though, there’s an even better reason for us air-scent handlers to engage in discrimination cautiously, if at all: it’s flippin’ hard to do right, and if you screw it up it’s worse than useless.

Without taking away the slightest from what trailing handlers do, the tactical, navigational, and team leadership demands on an air-scent handler require a pretty serious, ongoing time commitment to acquire and maintain; the challenges of working with and communicating with a dog who’s working at liberty aren’t trivial either [5]. By no means is it impossible to do this alongside training for scent discrimination. But it ain’t easy, and again, if you don’t do it at a very high level of accuracy indeed, you’re by definition sucking at it.

Enter item number one, shared by th’ wife: a lawsuit against the only dog handler in Texas who uses scent lineups to identify crime suspects. Seems that at least two of the folks his bloodies fingered — so to speak — turned out to be innocent, and now they’re out for, um, blood.

Now, I don’t know this guy or his training methods. His dogs may be 99 percent accurate — but that still leaves one suspect out of a hundred who’s screwed, if the courts accept the dog’s nose as evidence.

More to the point, I doubt that anybody has put a numerator to his denominator and found out, for training or in the field, what his accuracy actually is [6]. And that’s a big part of the problem. Get this, from a lawyer with the Innocence Project of Texas:

“This is junk science. This isn’t even science. This is just junk.”

Now, in my book the Innocence Project folks are among the Good Guys. It hurts to hear one of them say this; it hurts even worse that, by the current standards of practice, he’s probably right.

The problem is that it’s so hard to work with a dog without cueing her as to what you want her to do. For us airscent dog handlers, it’s relatively simple: just don’t tell me where the training subject is hidden; either I find him or I don’t, and in theory at least it should be simple to demonstrate whether having the dog with me increases my search effectiveness or not [7].

For scent discrimination the task is harder. You can do a certain amount of screwing up without messing up a non-discriminating air-scent dog’s training; but every time you reward a discriminating dog, you train her; every time she self-rewards without being corrected for a faulty identification, you train her. Most discriminating handlers, therefore, spend most of their training time unblinded; they know what the answer is, so they can jump in and reward the right and correct the wrong.

The problem is, sometimes, without realizing, we jump in before the dog has actually committed to a choice, even by a fraction of a second: and thus we train the dog to tell us what we want or expect rather than the real answer. Good discriminating handlers proof themselves periodically with a blinded problem; but I worry that a lot of practicing handlers haven’t done that, or if they have, haven’t kept track of how often they mess up.

What we want and expect matters to our dogs. It seems undeniable to this working handler that our dogs read us far more effectively than we will ever be able to read them. The slave knows the master better than the master knows himself, as Heather is fond of abstracting the otherwise inabstractable Hegel.

The end result is that, even among the best scent-discrimination handlers, I don’t know how well established the standards of practice are for high-stakes lineup identification — not that you’re not doing well, just that you don’t have a handle on the actual number, and so can’t be sure.

Perversely, as we see from a review in Science, when the stakes are highest is exactly when we’ll do what we don’t want to. A phenomenon called the “ironic monitoring process” stems from the fact that intending not to do something requires us, at some level, to focus on it — which in turn makes us more likely to do it.

People do have the ability not to “mention the war:”



Our brains can, in fact, achieve the tricky balance of concentrating just enough on something to avoid it without concentrating enough to dive straight into it. But it’s difficult, and if we’re tasked with other stuff — whether actual distractions or the distraction of stress — we’re more likely to blurt out something about Hitler.

Particularly interesting in this context is a task in which one person who can see four shapes — say, a small triangle, a circle, a heart, and a large triangle — is asked to point out the small triangle to someone who can’t see the large one. It’s not at all uncommon for the first person to refer to the target shape in a way that tips off what the hidden one is: for example, by saying “look at the  small triangle.” And they’re more likely to do that if you tell them to keep the large triangle a secret than if you don’t.

There is, for us dog handlers, another way: in the early days, defense attorneys were more than leery about DNA forensics. They anticipated, quite correctly, that if we didn’t hold the field to high standards, it would result in bullshit convictions. But the guys in the DNA forensics field did their homework, refined their numbers, and today I think that in general defense lawyers love DNA testing: in the cases for which it’s relevant and doable, and when the meaning of its results are accurately reported to the jury, it is the quickest, easiest way to get innocent defendants back to their lives.

We can do this in the dog community. We can do our homework, put numbers to our abilities, and find out exactly what we can and can’t do reliably; and at that point, a jury can take our evidence for exactly what it is.

A few years back I did an article for Advanced Rescue Technology about SAR dogs and olfaction. I had the opportunity to interview Larry Myers, one of the few scent researchers who’s consistently interacted with working dog handlers, for that piece, and along the way we got into a discussion about the reliability of dog scent evidence in legal proceedings. The editor decided to let me do this as a sidebar to the scent article; my only regret is that I didn’t think of proposing it as a more in-depth, stand-alone article, but you can read it here.

The short version is that, for the level of certainty of probable cause — the gauge of reasonable suspicion a cop, once he’s stopped you for a traffic violation, needs to have in order to search your car for contraband — Larry thinks that dog evidence is OK; but for beyond reasonable doubt — what you need to convict someone of a crime — not so much. For what it’s worth, I tend to agree with him.

Nor should we feel like second-class citizens in being asked to do this. Reasonable doubts have begun to pop up with a number of common identification procedures, ranging from polygraphy to eyewitness identification [8] to, of all things, fingerprints. The common factor of these methods: they came into use before the courts started looking at the scientific bases behind methods, and so got enshrined based on “common sense” or, maybe even worse, the opinions of “experts,” itself a slippery term that I tend to try to avoid. Quantitative evidence is the wave of the future: we hold it at bay at the risk of bringing about our own irrelevance.

[1] Yes, it occurred to me too. But it’s not the strangest thing I’ve encountered regarding a search or a search subject.
[2] Briefly: on an earlier task the previous day — a hasty along the top of a ridge to the east of the ATV — a ranger, because of a miscommunication with the operations folks, left us off at a completely different location than our intended jump-off point. In those pre-GPS days, it amounted to leaving us in the middle of the woods without the slightest idea of where we were. Efforts to align our surroundings to the terrain proofed fruitless until my walker noticed that we were standing next to the confluence of two creeks — and our map only showed one such intersection. Once we knew our spot, it was simply a matter of shooting a bearing to where we’d intended to start, and then following through with the task. We never had to ask for help, and completed our assignment — took us a few extra hours, but we did it.
[3] If you don’t have anything to eat, you don’t need your insulin.
[4] At least once, I did have reason to believe we’d missed a subject on a real search because my dog had been distracted by finding someone else in my area. But that’s more an argument for not letting people — either civilians or other searchers — get into each other’s assigned areas than for scent-discrimination per se.
[5] For the record: as I train to become a trailing handler, I find the level of handler-dog communication necessary to work trailing to be daunting. But it’s a distinct and different type of communication from that of an airscent team.
[6] As some of you may know, we’re in the process of doing something much like this with our own dogs’ performance. The preliminary results are encouraging in terms of showing something objective; but it’s a long-term project, and I don’t know how long before we get results that I’d subject to peer review. Stay tuned.
[7] Again, stay tuned.
[8] Wikipedia also has an article that encompasses the “anti” argument fairly well, though it has been tagged for non-neutrality.

Thursday, July 9, 2009

Pathbreaking

I know I have the fire service on the brain lately. It’s mainly because I’m at the “easy” part of the learning curve, in which you know so little that every gain — even if you’re taking only baby steps — seems huge. I think I’ll go elsewhere for inspiration next time, but I had one more fire-company story to share first.

Last week marked another “first” for me — the first time I participated in the Independence Day parade with my company.

You’ve got to understand, this is an iconic thing for me. As a tad I would line up to watch my grandfather and his brothers-in-law march down the street — I can’t remember whether South Hackensack had its own parade, or it was part of a larger procession in Hackensack, but in that, um, slimmer era firefighters marched as well as drove their trucks. South Hackensack Company Number Two being an informal (by the standards of the day, which seem fairly formal these days) production, the chieftaincy rotated; but I know my grandfather, Salvatore Gulino, served as chief for at least one term.

One of my earliest memories is of spending the night at my grandparents’, and of waking when the town horn went off — a Morse-code-like pattern told the firefighters where the fire was in that pre-scanner era. Outside my room, I could hear rustling as my grandfather got dressed and went out to help somebody who was in trouble.

The man was twenty feet tall.

So as you can imagine, marching with the company carried a huge amount of baggage — in the best possible sense of the word — for me. Last year I didn’t do it because, mere days into my membership, it didn’t seem right. Now I’ve responded to some calls, gotten some training, have some history with these guys. So this year, I knew I’d participate.

I had a welcome surprise coming; Neil, our assistant chief, took me aside and told me, “I want you to drive the squad.” Now, being assigned to drive was an unmitigated honor; but in all honesty, the “squad” — a van that carries odd roadside tools and which the guys at our substation chiefly use to get to incident scenes when the tanker isn’t needed — is a pretty lame vehicle.

As if I needed to be reminded of this, they had to pull one of the junior members off an engine — actually, it was my partner from Fire School — so we’d have more than one person in the vehicle. There weren’t going to be any volunteers, you see.

“How am I going to impress the chicks now?” he asked me.

In my best avuncular mode, I suggested, “You could always tell them it’s the pussy wagon.”

He brightened slightly: “Hey, that could work.”

“No, it won’t,” I laughed.

Anyhow, we lined up — I believe the brush truck came first, then the rescue truck, us, and then the engines, starting with “23” [1], and finally the tanker.

The parade was, of course, a low-velocity follow-the-leader thing down Main Street, plodding like ducks in a row; the squad having an automatic transmission, I was riding my brakes all the way. I didn’t see Heather and my Cleveland relations — we’d imported a houseful of them for the holiday — partly because I was so intent on monitoring my peripheral vision for any kids who might dash into the street. Between that, and the obligation to wave back as we drove by, my attention was surprisingly filled for what I think was a half-hour drive.

Anyhow, my point being, when your navigation consists of putting your nose into the next guy’s butt, it isn’t much of a challenge. Which brings us to our current entry, a fascinating video study of wayfinding by rats (note that this journal has a limited-time one-day free subscription, so if you hurry you can view this for free).

Primarily a brain-function study rather than a scent study, it consisted of having rats follow a scent trail to a food reward, and then — and it’s this second step that’s important — seeing what they did next, as the normal behavior would be to rush straight back to their hole to cache the goodies.

In some of the animals, the researchers had surgically damaged the ability of the hippocampus, a memory- and spatial-sense-associated part of the brain, to move information. This removed the animals’ ability to dead reckon — basically, get to where you want to go by remembering how you got where you are, without either following a guide or other external navigation method. They used dark conditions and little hoodies for some of the rats to make sure they weren’t navigating by sight.

Both the animals who received this surgery and those who received sham surgery — meant to rule out any effect from anesthesia or non-hippocampal-effects of the surgery — were able to follow the scent trails pretty well. Some individual variation, but I don’t believe any significant difference.

Again, though, it was that return trip that posed the problem: the hippocampal-operated rats just couldn’t do the quick, effortless dash back to the hole. They took longer; they made a lot of mistakes, sometimes going to the wrong hole; one enterprising individual even back-trailed on the scent trail. But their ability to simply remember the direct path back to their hole was no longer there.

I don’t have much to add to this one, except to point out how powerful the simple video is; and how amazing it is that web technology allows this kind of work, and this kind of journal, to exist.

Would it be cheesy to call it pathbreaking?

[1] Interesting fact here: soon after I joined, I learned that, of our three engines, 23, 23-2, and 23-3, 23 never rolls. I assumed at the time, and from the numbering, that 23 was the oldest engine and so the chief liked to employ it as a reserve instead of in daily use. Oh no, I come to learn: 23 is the replacement for the old 23, and is in fact the newest of the three. It doesn’t roll because the chief doesn’t want us to get it dirty. That taught me something about fire chiefs; I kid, but you know, the more I think about it, the more I think that mind-frame is a good thing in a chief.