Friday, October 20, 2017

Spiders and the shrew brain

What can I tell you about spiders? Spiders have eight legs. Spiders' legs need vascular pressure to straighten. Their natural, relaxed state is bent. That's why their legs curl up when they croak.
We’re supposed to like spiders. Spiders are good. Spiders eat bugs that bug us. Spiders recycle sewage into rainwater. Spiders give us spider honey and spider silk. Spiders make friends with barnyard pigs.
But. Only. There's a spider-shaped set of linked cells in the visual cortex. Linked by a web of connections all the way down to the part of the brain that's left over from when we were the size of shrews, running around under the feet of tyrannosauruses. The spider-shape triggers that spider-shaped set of cells, which sends a spike of action potentials (if you could detect them with a Geiger counter the clicks would blend together in a hum)—sends that spike signal down into the shrew brain, and the shrew brain says, "Squish it! Squish it NOW!"
You can override it. Your big folds, Mr. Cortex Guy, they can override the squishing reflex. Tell you that the spider is your friend, etc., etc., blah, blah. The cortex does drone on a lot. Can let you look at pictures of wolf spiders with all their hair and rows of black, beady eyes staring at the camera. Lets you pet tarantulas, if you're the type that pets tarantulas. But underneath, your shrew-monkey-cretaceous-mammal brain is screaming, "Squish it squish it squish it squish it now before it kills you!" Because the little shrew-monkeys without arachnophobia all got eaten by spiders. Only the others reproduced. Or reproduced more.
Eventually it causes problems, this dissonance between the outer and inner brain parts. Makes your eyes start to vibrate. Makes you squish other things, since you can't squish the spiders. There was an arachnologist once who got arrested for squashing all the kiwifruits at the Safeway. "They were looking at me," he said as they hauled him away. "All furry, with their beady little eyes. Had to squish 'em before they sprouted legs. Once they do that, they crawl into the heating ducts and you can never get 'em all out."
I know this about the shrew-monkey brain because it happens to me. The side of the house is Spiderville. Spider City. Especially toward the end of the fall. They're orb-weaver spiders, mostly. Big webs that look just like your textbook, comic-book spider webs. The owner hangs upside-down, right in the middle.
I was out there one night last fall, poking around in the bushes and spider webs with a flashlight, looking for the breach where some itchy little squirrels were getting into the walls and scuttling around. I felt something on my arm. It was a spider. Big, fat spider, abdomen the size of a grape, where you could see stripes and segments, see the row of little holes the spider breathes through—spiracles?—in the small circle of light from the flashlight. Feel the touch of eight brushing legs. Feel, I swear, the prick of venomous fangs testing my skin for the tenderest spot. I shuddered. For real, and I'm not a shuddering kind of person. Shuddered, flailed at the spider. Brushed it off, and my shrew brain had me stamping on it over and over in the rain.
I'm sorry now. A little bit. But my shrew brain keeps telling me I did the right thing.

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