At this very moment it's November, but it's still hot in New York; hot by my Chicago standards, anyway. I am ... well I think I've got a touch of a fever; it's been breweing as a cough for about a week, so I'm sweating, very warm. But I'm also suffering, at the torment of an evolutionary bully.
I'm temporarily staying with a coworker in his run-down Brooklyn apartment. The most important detail of my particular, admittedly unimpressive plight, is the windows in his three room apartment have no screens. Instead, many of these old buildings have these telescoping screen frames that are just propped up inside the window.
They do keep some of the bugs out, but the mosquitoes; practically the whole purpose of screens; they just pour right in; so long as the weather is above about 40 degrees.
I can tell, with just a glance in the mirror, especially in just the last couple of days, that I sleep on the right side of my body. It's illustrated in grotesque detail on my left arm; which is covered in scabs and scars, all of which have been acquired in just the past few weeks. I sleep soundly on my right side, and throughout the night they feed on the one part of me they can access.
A few hours later, I notice a slight itch, and I'll find a huge welt on my arm, or shoulder, or leg, or wherever. Within 12 hours, the large welt will sort of shrink into a tiny blister, maybe an eighth of an inch wide. The welt itched a bit, but blister itches like crazy. I'm complete unable to resist scratching at it.... I don't mean I'm fine one minute, and then completely and convulsively preoccupied with scratching an itch that wont' go away for an hour (though sometimes it feels that way), rather, I'll be minding my business, and instinct just drives me to reach over, and just scratch it, just a little. Half a beat later I realize and stop. Then a few minutes later it'll happen again.
This only has to happen like three times, just a little scratch, just here and there, and the blister breaks wide open, and blood starts oozing out of an even itchier wound, now a quarter inch wide. And they scab over and turn into these ugly scars. The worst part is, even if I do resist; It still scabs over, I still get the scar; it's just a little smaller.
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Okay, enough complaining. People are dying all over the world from diseases transmitted by mosquito bites and this guy is complaining about the itching? I can almost hear you say. I don't really want to talk about my itching. I'm more interested in the itching; as in, "Why does it even itch?", "What's the point?"
See, mosquitoes are really old, a lot older than humans; somewhere between 75 to 100 million years old, depending on when you want to call this thing a mosquito, but that thing is just a more primitive fly (did you mosquitoes are a type of fly?). They've been around so long you could sort of say that mosquitoes are really good at "being mosquitoes".
With their short life cycles, they get extra chances at getting it right; A typical mosquito completes its life-cycle in warm months in around 40 days. That's like a year of its whole life for every day of a human's life cycle, or maybe a week of a smaller mammal. 75 million years of mammal evolution is like half a billion in mosquito years.
So... For almost all purposes, mosquitoes are close to perfect. If a trait doesn't really do them any good, they'll probably just, ditch it.
At any rate, 75 million years is plenty of time for mammals to deal with an accidental allergic reaction to mosquito saliva.
And so I wonder, "The mosquito drifts in, practically unnoticed, steals its meal, and it's gone from my life forever. Only later does the itching start. How can it possibly serve the mosquito after it leaves?"
I try flipping the idea on its head "Ok, maybe it doesn't serve the mosquito, it serves me. I react to the saliva and notice the mosquito just before it gets a chance to transmit some horrible parasite... but it doesn't itch at all until after the mosquito is long gone"
And the whole time as I'm reasoning this out, I catch occasional glances of a mosquito in the corner of my eye. If I feel a breeze or a twitch, in the back of my mind "oh, is that the mosquito landing on me?" and I reach to smack it ... and ... no, it's an old bite. And then I feel something else on the other side of my body: "Oh is that the mosquito" and I reach to slap that, but it's another old bite.
And now I'm actually thinking "Damn it if a mosquito really does land on me, I'll never notice it over all the itching... "
"Oh..." And the obviousness of it seems kind of ridiculous. It's never one mosquito, it's usually a whole swarm of them, one or two at a time, over the course of the whole summer (or in this case, autumn; I had arrived in October). It doesn't really have to serve the first mosquito, because it will serve the next. Once a host has been bitten a few times, and they itch in several places, the mosquito can slip in between the noise.
And come to think of it, It doesn't even have to be one mosquito after the next. I arrive in new york, exhausted from travel. I collapse on the air mattress and fall almost immediately into a sound slumber. When i wake up, there's not just one or two welts, but a dozen, all clustered around my forearm. And I think this was one mosquito, because I caught it a day or two later, and was undisturbed my mosquitoes for several more days.
Almost like the mosquito was laying a trap. I picture it scanning around my bed, looking for the best place to plant its nefarious seed, and it homes in on my forearm; exposed, easy to get to or away from.
And it lands, and then hops right back into the air. It doesn't even try to bite. Right now its just... testing. To see if i'm really asleep. after circling around once, she lands again, this time in almost the same place, but this time she bites. But she still doesn't stick around, she's back in the air immediately. Just checking to see if I'm sound asleep or just half asleep. She does this a few more times, each time landing in a slightly different part of my forearm, and injecting just a little bit more saliva.
And then, after she's done this a half a dozen times, even more; she still hasn't tasted a single drop of my precious humor; she flies away. Not too far, just... out of site. She waits. Just long enough for the allergy response to start.
And then she strikes. Boom, a completely different part of my body. Even if I do wake up; she's safe. I'll be so preoccupied with the itch on my forearm I won't even notice where she's really working. I'll shift around to reach my forearm, and she can just escape.
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One more thing though... I mentioned that I'm new to New York. We have mosquitoes in Chicago, too. And they never seem to bother me. I smack them off my arms all the time, and never (or hardly ever) mistakenly slap an existing bite. Like the allergic reaction is just missing.
I think what's going on here is that the different populations of mosquitoes are interacting with my immune system in very different ways. In that environment, I was winning; the bites didn't itch, and so if I felt an little bit of an itch, it was not a bite, but an actual mosquito, and I could catch 'em.
