On ‘The Overstory.’

On ‘The Overstory.’

We delude ourselves into thinking that the pace of life has increased in recent years.  National news is made by the minute as politicians announce their plans via live-televised pronouncement or mass-audience short text message.  Office workers carry powerful computers into their bedrooms, continuing to work until moments before sleep.

But our frenzy doesn’t match the actual pace of the world.  There’s a universe of our own creation zipping by far faster than the reaction time of any organism that relies on voltage waves propagating along its ion channels.  Fortunes are made by shortening the length of fiberoptic cable between supercomputer clusters and the stock exchange, improving response times by fractions of a second.  “Practice makes perfect,” and one reason the new chess and Go algorithms are so much better than human players is that they’ve played lifetimes of games against themselves since their creation.

640px-IFA_2010_Internationale_Funkausstellung_Berlin_18We can frantically press buttons or swipe our fingers across touch screens, but humans will never keep up with the speed of the algorithms that recommend our entertainment, curate our news, eavesdrop on our conversations, guess at our sexual predilections, condemn us to prison

And then there’s the world.  The living things that have been inhabiting our planet for billions of years – the integrated ecosystems they create, the climates they shape.  The natural world continues to march at the same stately pace as ever.  Trees siphon carbon from the air as they grasp for the sun, then fall and rot and cause the Earth itself to grow.  A single tree might live for hundreds or thousands of years.  The forests in which they are enmeshed might develop a personality over millions.

Trees do not have a neural network.  But neither do neurons.  When simple components band together and communicate, the result can be striking.  And, as our own brains clearly show, conscious.  The bees clustering beneath a branch do not seem particularly clever by most of our metrics, but the hive as a whole responds intelligently to external pressures.  Although each individual has no idea what the others are doing, they function as a unit.

Your neurons probably don’t understand what they’re doing.  But they communicate to the others, and that wide network of communication is enough.

Root_of_a_TreeTrees talk.  Their roots intertwine – they send chemical communiques through symbiotic networks of fungal mycelia akin to telephones.

Trees talk slowly, by our standards.  But we’ve already proven to ourselves that intelligence could operate over many orders of temporal magnitude – silicon-based AI is much speedier than the chemical communiques sent from neuron to neuron within our own brains.  If a forest thought on a timescale of days, months, or years, would we humans even notice?  Our concerns were bound up in the minute by minute exigencies of hunting for food, finding mates, and trying not to be mauled by lions.  Now, they’re bound up in the exigencies of making money.  Selecting which TV show to stream.  Scoping the latest developments of a congressional race that will determine whether two more years pass without the slightest attempt made to avoid global famine.

In The Overstory, Richard Powers tries to frame this timescale conflict such that we Homo sapiens might finally understand.  Early on, he presents a summary of his own book; fractal-like, this single paragraph encapsulates the entire 500 pages (or rather, thousands of years) of heartbreak.

image (2)He still binges on old-school reading.  At night, he pores over mind-bending epics that reveal the true scandals of time and matter.  Sweeping tales of generational spaceship arks.  Domed cities like giant terrariums.  Histories that split and bifurcate into countless parallel quantum worlds.  There’s a story he’s waiting for, long before he comes across it.  When he finds it at last, it stays with him forever, although he’ll never be able to find it again, in any database.  Aliens land on Earth.  They’re little runts, as alien races go.  But they metabolize like there’s no tomorrow.  They zip around like swarms of gnats, too fast to see – so fast that Earth seconds seem to them like years.  To them, humans are nothing but sculptures of immobile meat.  The foreigners try to communicate, but there’s no reply.  Finding no signs of intelligent life, they tuck into the frozen statues and start curing them like so much jerky, for the long ride home.

Several times while reading The Overstory, I felt a flush of shame at the thought of how much I personally consume.  Which means, obviously, that Powers was doing his work well – I should feel ashamed.    We are alive, brilliantly beautifully alive, here on a magnificent, temperate planet.  But most of us spend too little time feeling awe and too much feeling want.  “What if there was more?” repeated so often that we’ve approached a clear precipice of forever having less.

In Fruitful Labor, Mike Madison (whose every word – including the rueful realization that young people today can’t reasonably expect to follow in his footsteps – seems to come from a place of earned wisdom and integrity, a distinct contrast from Thoreau’s Walden, in my opinion) asks us to:

image (3)Consider the case of a foolish youth who, at age 21, inherits a fortune that he spends so recklessly that, by the age of 30, the fortune is dissipated and he finds himself destitute.  This is more or less the situation of the human species.  We have inherited great wealth in several forms: historic solar energy, either recent sunlight stored as biomass, or ancient sunlight stored as fossil fuels; the great diversity of plants and animals, organized into robust ecosystems; ancient aquifers; and the earth’s soil, which is the basis for all terrestrial life.  We might mention a fifth form of inherited wealth – antibiotics, that magic against many diseases – which we are rendering ineffective through misuse.  Of these forms of wealth that we are spending so recklessly, fossil fuels are primary, because it is their energy that drives the destruction of the other assets.

What we have purchased with the expenditure of this inheritance is an increase in the human population of the planet far above what the carrying capacity would be without the use of fossil fuels.  This level of population cannot be sustained, and so must decline.  The decline could be gradual and relatively painless, as we see in Japan, where the death rate slightly exceeds the birth rate.  Or the decline could be sudden and catastrophic, with unimaginable grief and misery.

In this context, the value of increased energy efficiency is that it delays the inevitable reckoning; that is, it buys us time.  We could use this time wisely, to decrease our populations in the Japanese style, and to conserve our soil, water, and biological resources.  A slower pace of climate change could allow biological and ecological adaptations.  At the same time we could develop and enhance our uses of geothermal, nuclear, and solar energies, and change our habits to be less materialistic.  A darker option is to use the advantages of increased energy efficiency to increase the human population even further, ensuring increasing planetary poverty and an even more grievous demise.  History does not inspire optimism; nonetheless, the ethical imperative remains to farm as efficiently as one is able.

The tragic side of this situation is not so much the fate of the humans; we are a flawed species unable to make good use of the wisdom available to us, and we have earned our unhappy destiny by our foolishness.  It is the other species on the planet, whose destinies are tied to ours, that suffer a tragic outcome.

Any individual among us could protest that “It’s not my fault!”  The Koch brothers did not invent the internal combustion engine – for all their efforts to confine us to a track toward destitution and demise, they didn’t set us off in that direction.  And it’s not as though contemporary humans are unique in reshaping our environment into an inhospitable place, pushing ourselves toward extinction.

Heck, you could argue that trees brought this upon themselves.  Plants caused climate change long before there was a glimmer of a chance that animals like us might ever exist.  The atmosphere of the Earth was like a gas chamber, stifling hot and full of carbon dioxide.  But then plants grew and filled the air with oxygen.  Animals could evolve … leading one day to our own species, which now kills most types of plants to clear space for a select few monocultures.

As Homo sapiens spread across the globe, we rapidly caused the extinction of nearly all mega-fauna on every continent we reached.  On Easter Island, humans caused their own demise by killing every tree – in Collapse, Jared Diamond writes that our species’ inability to notice long-term, gradual change made the environmental devastation possible (indeed, the same phenomenon explains why people aren’t as upset as they should be about climate change today):

image (4)We unconsciously imagine a sudden change: one year, the island still covered with a forest of tall palm trees being used to produce wine, fruit, and timber to transport and erect statues; the next year, just a single tree left, which an islander proceeds to fell in an act of incredibly self-damaging stupidity. 

Much more likely, though, the changes in forest cover from year to year would have been almost undetectable: yes, this year we cut down a few trees over there, but saplings are starting to grow back again here on this abandoned garden site.  Only the oldest islanders, thinking back to their childhoods decades earlier, could have recognized a difference. 

Their children could no more have comprehended their parents’ tales of a tall forest than my 17-year-old sons today can comprehend my wife’s and my tales of what Los Angeles used to be like 40 years ago.  Gradually, Easter Island’s trees became fewer, smaller, and less important.  At the time that the last fruit-bearing adult palm tree was cut, the species had long ago ceased to be of any economic significance.  That left only smaller and smaller palm saplings to clear each year, along with other bushes and treelets. 

No one would have noticed the falling of the last little palm sapling.

512px-Richard_Powers_(author)Throughout The Overstory, Powers summarizes research demonstrating all the ways that a forest is different from – more than – a collection of trees.  It’s like comparing a functioning brain with neuronal cells grown in a petri dish.  But we have cut down nearly all our world’s forests.  We can console ourselves that we still allow some trees to grow – timber crops to ensure that we’ll still have lumber for all those homes we’re building – but we’re close to losing forests without ever knowing quite what they are.

Powers is furious, and wants for you to change your life.

You’re a psychologist,” Mimi says to the recruit.  “How do we convince people that we’re right?”

The newest Cascadian [a group of environmentalists-cum-ecoterrorists / freedom fighters] takes the bait.  “The best arguments in the world won’t change a person’s mind.  The only thing that can do that is a good story.”

On memory (part 2).

Read part 1 here.

Note: not the actual wedding I attended.
Note: not the actual wedding I attended.

Midway through spring, we found ourselves in Chicago for a wedding.  K was asked to be best man, and since N was (is) still breastfeeding, she and I had to tag along.  I’m not a big fan of weddings, but I did sneak in a lovely conversation with the groom’s younger brother.

He, the younger brother, is an artist (music, film, theater) who recently started working on a degree in journalism.  During our chat he mentioned that he’d become interested in memory after a traumatic head injury — he found it fascinating / alarming that there is a gap in his own mental records for the swath of time before and after that incident.  I didn’t ask, but it’s possible this incident inspired his foray into journalism; I can imagine written records taking on a newfound importance for someone subject to an involuntary lesson in the fragility of biological memory.

Part of why I don’t care much for weddings is the perpetual bustle — it’s hard to finish a good conversation because there’s always something else about to happen, somewhere else you’re supposed to be standing.  Next time, perhaps, if we remember, we can finish talking about this.

One thing he did have time to say, though, was: “Memories are physical things, right?  They exist in your brain.  I was wondering whether someone could analyze a brain and learn what memories are there.”

I rattled off only a partial answer before he was whisked away for photographs.  My answer, as it happens, was incorrect as to the current state-of-the-art for mind reading — I’d recently seen this press release titled “Scientists crack piece of neural code for learning, memory.”  After reading it, I had the impression that the group was able to visually inspect a region of the brain and know which of two memories had been encoded, either if you hear a high-pitched sound, move right or a similar memory instructing a rat to move left instead.

3461234232_19b63c79d7_oWhich seemed believable to me; yes, that’s a very hard problem, but if the group was investigating only a single, simple type of memory, one that was always stored in the same part of the brain, and was attempting to differentiate between only two choices… well, yes, it still seemed difficult, but at least they’d know where to look.  The impression I have is that data recovery from crashed computer hard drives is difficult primarily because any given piece of information might be stored in a variety of places, and that the major calamity isn’t usually that your documents, pictures, etc. are lost, but that the pointers, the addresses for where each document, picture, etc. is stored, are lost.

And computers are devices we designed!  Attempting to recover data from a brain, a system in which we don’t really know what the data would look like even if we knew where it was, sounds many orders of magnitude more difficult.

Still, I’d read that press release and thought one tiny piece of the puzzle had been solved.  That post-mortem visual inspection could unveil one particular binary known-to-be-present memory.

I was wrong.

Before typing this post, I downloaded the actual paper (Xiong et al.’s “Selective corticostriatal plasticity during acquisition of an auditory discrimination task,” although I should warn you that it isn’t open access) and attempted to puzzle through what they’d done.  I’m still shaky on the details, so my apologies if I make any mistakes in this ensuing description.

A flat slice of some poor rat’s brain showing the auditory cortex.

They modified a small population of brain cells to respond to light.  After shining light on these cells, they recorded the responses in another part of the brain — the cells in your brain look something like squids, with a head region that collects signals and tentacles that reach out to send those signals somewhere else, and as best we know memories are encoded through the pattern of linkages between those squids… er, cells — as a measure of the link between those brain regions.

After training a rat to move left when it heard a high-pitched sound, they expected the cells in a “we respond to high pitches” brain region to have stronger connections to / more & more powerful tentacles reaching into the “we move left” brain region.  And, yup, while they were training each rat they took occasional breaks to shine light onto the modified cells, and they did observe stronger signals in the “move left” brain region.

They could also distinguish between a brain slice from a dead rat that had been trained to associate “high-pitch / move left” from one that had been trained to move right with the same strategy: shine light on the pitch recognition region, look at signal in the movement region.

My mistake, then, was thinking they could assess synaptic strength visually — I thought they were inspecting brain slices under a microscope to determine what memory was there.  Their measure for signal strength was “local field potential,” though, which sums the contributions of many cells… so it seems possible that they could have arduously traced out the tentacles from each cell in their pitch region to see how many were reaching into each movement region.  Which would obviously be a huge pain — the brain is messy, and those tentacles are very small — but it seems feasible.

And, sure, I hadn’t realized they were using rats whose neurons were modified via viral infection… although it seems like visual assessment could be done using unmodified cells.  With the caveat being, of course, that making a 3D model showing all the outcroppings of every cell in even a small region of the brain would be incredibly difficult.

Anyway, this seems to be the current state of the art for learning what memories were stored in the brain of a deceased rat.  For humans, we can do even less.  If you happen to have a few heinous memories tucked away, don’t worry; if you die soon, those memories will die with you.

Of course, these fields are advancing all the time.  If you take too long to die, all bets are off.


GolgiStainedPyramidalCellp.s. Synaptic strength isn’t just a measure of the number of tentacles… to elaborate on our metaphor, those tentacles also froth forth with little bubbles of neurotransmitters, and the quantity of those waiting bubbles can change, the density of receptors on the next cell in line can change, etc., and all those changes (and more!) seem to play a role in memory formation.  A perfect 3D map of where each neuron’s axons reach to, where each neuron’s dendrites are grasping from, wouldn’t be enough.

And even if we could obtain all that, a full list of every synaptic strength, we’d still have to puzzle out what all the information means.  How do those connections result in an image of your grandmother’s basement?  A narrative of your youth?  No one knows.  So your horrible secrets will probably be safe even if you die a very long time from now.  Unless you forget to burn your diary.  Then future sleuths could simply bypass your encrypted brain.  And wouldn’t you feel silly!