Nature’s Brains, Part 5

July 8, 2012

Bob Fiske

Nature’s Brains, Part 5

(Note: I invite you to read Part 4 before you dive into this part.)

If you have followed this essay so far, you might have thought I was doing a term paper for a biology class.  You could be excused, for you did not know the question that motivated it.  But it’s not a term paper, it’s an editorial.  You might say this is a bio-political opinion piece.

Now here is where I’m going to look pretty dumb.  An editorial author is supposed to have a single, solid opinion.  I don’t.  I haven’t made up my mind yet.  It’s because of the question I asked.

A question popped into my mind as I “observed” the inner workings of the feeding sparrow’s marvelous little brain, as I recognized that brains are useful and that nature has kept improving their designs, that, in the human brain we see both the splendor and drawbacks of advanced brain design, and that, from nature’s point of view, the drawbacks are a supremely serious problem.

And this question entered my mind.  “Are brains obsolete?”  Is nature done experimenting with brains?  That’s the question.

Here, in a nutshell, is my ambivalence on the issue.  The human brain has supplanted nature.  Or: the human brain appears to think and act like it has replaced nature.  Or: perhaps the human brain will, in fact, displace nature in determining the future of all life on the planet.  Or: probably not, nature will win and will phase out brains.

One might reply, “Phase out brains?  It could never happen!”  Want to bet?  We have evidence of other design solutions that were edited out of nature’s animal catalogue.  For instance, the dinosaurs.  Although dinosaur fossils have been found spanning a variety of sizes, for this discussion we want to focus on the most obvious group, the giants whose body masses were on the order of several metric tons.  They are no more.  That design was phased out.

Dinosaurs had a nice, long reign of over an eighth of a billion years.  Another grand animal design is represented by the trilobite group that inhabited earth’s early oceans for over a quarter of a billion years.  They, too, are no more.  So, it is possible that successful animal designs can enjoy popularity and still end up as throwaways in the genetic scrap heap.

OK, let’s back up a step.  Is nature a thing that is capable of making decisions?  Can nature phase out brains?  I want to be clear: talking about nature as if it is an entity that deliberately chooses which species to include or omit in a catalogue is merely a verbal shorthand.  While that shorthand makes it possible to express sentences using fewer words, I would not want you to become confused by it.

Therefore, to clear up any misunderstanding, I will place a small definition on the table.  Nature is a system of rules for structuring matter.  It turns out that this rule-base is huge, as is the number and type of forms it is capable of producing.  Nature does not think, nor does it plan.  And yet, as psychiatrist Allen Wheelis poetically argued, nature appears to “progress”.  Using verbal shorthand once again, I would say that it is possible to see in nature’s progress innumerable experiments in which forms have been tried out.

Certainly, in the arena of life, the “trying out” of forms (living designs, genotype/phenotype combinations) has a dynamic nature.  By dynamic, I mean that experiments can be performed using biological building blocks, and when the experiment is over those bio-molecules can be recycled into other organisms.  It’s like having a whiteboard or a computer hard drive that can be written and rewritten upon many, many times.

So, simply because the human brain is the most adept brain to be written onto nature’s slate is no guarantee of anything.  That genetic information can be wiped clean, and the raw materials can be assembled to make other designs.

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Nature's Brains, Part 3

July 8, 2012

Bob Fiske

Nature’s Brains, Part 3

(Note: I invite you to read Part 2 before you dive into this part.)

As nature continued to tinker with brain designs, sooner or later some sophisticated features were bound to arise.  In larger, brained animals, such as dinosaurs, the reptilian or “old brain” did little more than regulate basic bodily processes.  These brains sent “down” nerve impulses for modifying respiration, digestion, heart rate, and perhaps even body temperature.  The old brain could also chain together primitive movements known as reflexes.  Reflexes are simple and are coded in the spinal cord.  Through the dominance of the brain these simple movements could be orchestrated into more complex behavioral sequences, sort of like composing words from the letters of the alphabet.

The complex behavioral sequences could accomplish tasks such as hunting, mating, building a nest, walking, running, fighting, and so on.  How did the old brain come to encode the complex behaviors?  Through trial-and-error.  In other words, species went extinct or found a survival advantage based upon the behavior sets that were genetically hard-wired into their members’ brains.  These behaviors were determined by the DNA code in that species’ genes and were passed from generation to generation.  Learning of the sort that we take for granted had not yet been invented as a brain design feature.

Even today we are able to see in the “advanced” mammalian brain vestiges of hard-wired, genetically coded behavior.  One example of this is the newborn foal.  Within minutes of being born, baby horses struggle to their feet and begin to walk.  Seeing a fully developed behavior of this sort is fairly unusual in the mammalian brain because the innovations it has acquired generally impose a long development period on the young brain.

One of the premier innovations that enabled mammals to survive was the brain’s ability to learn.  This is anything but trivial (even though we take it for granted).  In order to learn, the brain needed to have a memory that could be loaded with new patterns.  But, for that to happen, the brain required an exquisitely complex coding mechanism that could replicate, in a “neural form”, qualities of the real world, a virtual model, so to speak.  This required more and more neurons in the brain.  The result is the “new” brain, a larger accessory that physically sits above and around the old brain.  All this new neural tissue was crammed into a larger skull in a folded and wrinkled fashion.  Scientists call this the cortex.

Parts of the cortex could more richly record auditory information or visual information.  Also, parts of the cortex were dedicated to producing complex movement sequences in various muscle groups such as the limbs, the mouth, the tail, the vocal chords, etc.

By the way, mammalian brains exerted pressure on other species to keep up.  So, we see that many birds (the descendants of the dinosaurs) also innovated their brain designs in similar fashion.  Maybe we mammals are not so special, after all, just lucky to come out in front of the race for survival.

Of course all this ability to encode a rich a faithful inner world model or command exquisitely complex movements would be better utilized if the brain were endowed with an equally rich storage system, that is, a memory.  The memory would allow multiple experiences in an individual’s life to be compared.  This is essential to learning (and survival), for it enables the search for cause-and-effect relationships to be found.

Here’s a simple example.  I am travelling with a herd of my companion mammals over an area of dry, parched earth.  Yet my eyes and visual cortex are able to discern a distant spot of green and brown as a concentration of things known as plants.  The brain, commanding the eyes to look more closely, enables the visual cortex to spy that this is a rich and dense collection of vegetation.  And the brain’s memory yields up a “conclusion” that other dense collections of vegetation have proved to be a source for water.  Even without the benefit of language that can name things, my mammalian brain has recorded (learned) the causal meaning of an oasis.

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