Saturday, January 28, 2012

Spiders are scary... or are they?

I read this today: "people tend to develop phobias for evolutionarily relevant threats (like snakes and spiders) rather than for things that are far more likely to kill them (like automobiles and electrical sockets)". So I got these 4 pictures and if you're anything like me you'll find that 2 of the objects appear benign, while two appear sinister to the point of causing discomfort.

Then it struck me that, once one understands evolution, this should have been incredibly obvious. One shouldn't find out something so simple and experience a feeling of enlightenment. Especially someone like me who considers themselves relatively intelligent and (accounting for age) relatively well-educated. This apparent paradox frustrated me, so naturally its been on my mind since I first read the original sentence.

The more I thought about it, the more I realized how utterly fantastic it is that we're able to experience such frustrations. There are 2 main reasons: we exist in a time where we can have the knowledge of something like that, and what the actual knowledge means.

We can compare time from the earliest life to 2012 by using a calendar. I calculated the calendar by scratch using a yellow pad and Wikipedia, so feel free to verify. There are of course some limitations to any such representation, but the underlying theme is well established fact. I set the start date of the calendar to January 1 at midnight, and the end date is December 31 at 11:59:59, and I'm using the calendar of the year 2012:

January 1st: Primordial ooze beings to exist
May 16, 9:00 pm: The great oxygenation event
September 12, noon: Sexual reproduction arises
November 6, 6:00 am: The first multi-cellular creatures arrive
November 10, 7:30 pm: The earliest brain appears via a flatworm. And these are still around! So consider that before defining *Homo sapiens* as the pinnacle of evolution.
November 14, 10:03 pm: The first vertebrate appears
November 27, 4:39 pm: The first recognizable limbs begin to appear
November 30, 10:12 pm: The first mammals appear
December 21, 9:00 pm: At this point there's a common ancestor of mice and men
December 27, 8:24 am: Primates diverge into subgroups
December 28, 5:15 pm: Old World Monkeys diverge from apes
December 29, 7:13 pm: The common ancestor of humans and great apes is alive
December 30, 2:08:44 pm: Very early hominin genus, they had brains 1/5 the size of modern humans
December 30, 5:25:48 pm: Loss of body hair, full bipedalism
December 30, 8:01:09 pm: Homo erectus is thrust into the world
December 30, 8:42:54 pm: We learn to control fire
December 30, 11:13:11 pm: The earliest anatomically modern humans
December 30, 11:50:19: pm: Behavioral modernity (e.g. using tools, symbolic thought, cooking food)
December 30, 11:52:02 pm: We leave Africa and interbreed with Neanderthals
December 30, 11:58:25 pm: Europeans develop light skin, Homo sapiens become the last living species of the genus Homo

This isn't comparing, say, from the Big Bang or even from the Earth's creation. This is just our ancestry! For the "first 364.99" days every living creature was incapable of anything much more complicated than fishing or drawing crude pictures. Even once Homo sapiens emerged, our first ~100,000 years we lived to around 25 and if we were lucky enough to avoid a brutal violent death our teeth would kill us. For emphasis from Jared Diamond: "the actual percentage of the population that died violently was on the average higher in traditional pre-state societies than it was even in Poland during the Second World War or Cambodia under Pol Pot."

And yet here we sit! The beneficiaries of a previously inconceivable explosion of safety and progress. We can reliably bet that we won't be murdered, we won't be robbed, and we can freaking download Wikipedia on a handheld device. We're so powerful our contraptions will render the Earth largely uninhabitable unless we purposely change our behavior. We're capable of walking on the moon, or investigating quantum mechanics. We're capable of studying human brains and behavior and the Universe in general and learning so much more than has ever even been conceived by previous generations! We're capable of recognizing the common link between spiders and ourselves, recognizing why we behave a certain way when we see one, and easily disseminating that information to anyone with access to books, the Internet or other people who know. Just think about that for a moment. Throughout almost all of time there has never been a creature capable of anything even remotely comparable to what we can do. Unless of course one wanted to define "greatness" as longevity in which case I think we'll have to hand that trophy to trees and flatworms.

Which brings me to the second reason my frustration, once reflected upon, became utterly fantastic. Think about everything that happened that led to the feeling of discomfort when looking at a spider. Untold generations of our ancestors had to get hurt by spiders - entire lineages dying out because of one interaction with one small spider - before we learned to instinctively recognize that a spider is dangerous. That feeling of discomfort are the genes of your ancestors crying out to you! The states of your brain today are being influenced by the interactions your ancestors had in the Pleistocene era. The lessons they learned by watching their neighbors die were learned so well that we can sit in our AC, drink tea imported from Japan, watch a video from Syria, eat fruit imported from South America, discuss the finer points of philosophy, and yet just the sight of an insect is enough for our ancestors to cry out so strongly it changes our brains. Like Neil deGrasse Tyson's stardust quote, that's a whole new level of connectivity we share with the world.

I think it's pretty cool.

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