The Bloodstained Palace of Memory

Be fruitful and multiply. Odd that the Origin of Species and the Old Testament have the same take-home message. Such revelation might upset the evangelicals, seeing how certain types keep telling them evolution is hostile to everything they hold dear. Then again, who knows. Even the Catholics came around eventually, removing Darwin from the fatwa list back in the 50s and again as recently as last week. Though you never could trust the papists, granddaddy always said. Maybe that's what really got JFK killed.

Origin is also rife with enough smoting to make Yahweh blush. Didn't see your predator? That's a smoting. Can't outrun your prey? That's a smoting. Not diverse enough? Make the unfortunate choice of nesting on top of an oil shale deposit or surfacing next to a Japanese whaling ship? Smoting. It's a wonder species don't go extinct every damn day.

Red in tooth and claw, Tennyson summarized this state of affairs. Which I suppose looks better on a movie poster than ...or form a symbiotic relationship that provides mutual benefit. Nietzsche didn't understand the middle part either. But let's leave such concerns for another day. Today we're interested in doing unto others, where "others" more often than not means members of your own species. Or, as it turns out, yourself.

We have met the enemy, Pogo quipped, and he is us.

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The human cerebral cortex contains some twenty billion neurons, a figure I sometimes see described in the literature as "hotly debated. Hotly debated. I picture Valentino Braitenberg and János Szentágothai tussling at the neuroscience conference. You fool! You have miscounted again! Take it back. Tack it back! Fisticuffs ensue, their little garter snake arms slapping ineffectually. Conference goers attempt to pry them apart as rows of posters fall like dominoes.

Whatever the number, it does not remain constant throughout life. Yes, there is some evidence of neurogenesis in a few select brain regions. The production of new neurons. But by and large the change is for the worse. Normal aging takes your brain cells, one at a time and in vast numbers. A 2003 study by Pakkenberg and coworkers published in Experimental Gerontology reports a grey matter loss of as much as 10% over the course of normal adulthood. Ten percent may not sound like much, but my back-of-the-envelope calculation figgers the equivalent average rate is ~86,400 neurons per day. Not coincidentally, it turns out there are 86,400 seconds in a day and, assuming my remaining decrepit synapses are still capable of long division, I believe that works out to one neuron death per second.

For comparison, here's other things that happen about once per second:

• a 1 Hz signal
• the heartbeat of a Tour de France bicyclist at rest
• a dashboard warning flashy light that won't deter any would-be thief since nobody pays attention to car alarms anymore because of Type-I error
• the wingtip navigation strobe on a 737
• the beat of We Will Rock You
• the time it took to read this item

I suspect you may be finding this news rather discouraging -- especially those of you old enough to vote or hire a rental car -- so let me attempt to soften the blow. The way your neurons die is rather entertaining! Comical almost, if you can get past the horrific implications.

As every schoolchild knows, neurons make action potentials. In your noggin at this very moment is a symphony of spikes traveling to and fro. When an elderly neuron dies, it action potentials itself to death. If you could listen in, it might go something like this:

plink... plink plink... plinkplinkplinkplinkplinkplink--

And then: nothing. As quiet as the grave as yet another cherished memory dissolves. In come the macrophages.

Bonus fact: "plink" is one of the few words you type entirely with your right hand. The more your know! Swishy Star.

Thus we add "plump brain" to the list of things wasted on the young. It's no coincidence the neural descent begins soon after our optimal breeding window closes. It makes sense, evolutionarily speaking. The Law of Competitive Exclusion states no two species may occupy the same ecological niche. One must drive out the other. A sort of Pauli exclusion principle for squishy things. Yet, the other members of your own species are about as niche as it gets. Even more so "old you" versus "young you," if you follow the logic. It would appear nature got impatient waiting for us to randomly stumble into an apex predator or in front of a bus. In addition to transcription errors and telomere shortening, it gave us a ticking neuron death waltz. A giant cosmic middle finger to us all. Welp, you've had your shot at passing along your genes, so we're just going to go ahead and start making your brain stupid so the tigers can take you. It's not personal. We just need the space.

The Palace of Memory, the brain has been called. There did the simple elaboration of excitable cells trump muscle and hide, tooth and claw. The ultimate victory over brawn. Yet, there does the Figured Wheel turn also. As on the savanna, as in the skies above and under the ocean sea, within those passageways the weak are culled so that the strong may grow stronger. There is no pity or remorse. It does not feel pain, the brain. It simply is. The deaths that rattle down through the eons are the same that echo down its hallways. They won't be remembered there either.