Excerpts – part 2

evo-devo

The most primitive part of the forebrain, which MacLean referred to as the “reptile brain,” includes structures that, according to him, provided the neural substrates for species-typical ritual or instinctive behavior, and basic homeostatic functions like breathing. Anatomically, you can think of the reptile brain as the brain stem and the associated foundational structures. Built on top of the reptile brain is the second component, which MacLean called the “limbic system”—a number of interconnected neural regions that support emotional responses from sexual to aggressive. According to MacLean, the limbic system evolved with the first mammals, so he referred to it as “paleomammalian.” The third component, called the “neocortex,” is found only in primates, according to MacLean. The neocortex, which surrounds the limbic system, is where the neural substrates for language, abstraction, planning, and other executive functions reside.

There are a number of problems with this “triune brain” hypothesis. For example, parts of the reptile brain are found in all vertebrates, including fishes; parts of the limbic system occur in reptiles; and the neocortex is not confined to primates. But by far the biggest problem with the triune brain framework is that it begins the story of brain evolution far from the beginning. Recent evo-devo research has revealed that not only our brains, but our vaunted neocortex, share homologies with the first brained creatures, called flatworms, with whom we share a common ancestor that existed prior to the Cambrian explosion over 500 mya. A lot happened in brain evolution between flatworms and fishes, and much more between fishes and reptiles. Our brains, perhaps more than any of our other organs, reflect the conservative tinkering nature of the evolutionary process.

Actually, we can trace brain tinkering to a prebrain stage, when the nervous system consisted solely of a network of a few neurons, such as we find today in jellyfish. Those neurons remained essentially the same, even as neural nets were transformed into complex brains like ours, and not because they are particularly efficient. The neurons we inherited from jellyfish are quite leaky with respect to the electrical charges they conduct. These leaky neurons were fine for jellyfish because jellyfish require only a few neurons to do what jellyfish need to do. For us and countless other more complex creatures, they are quite suboptimal, and the myelination of some axons is a make-do evolutionary response to ameliorate the problem.

If our neurons were more efficient electrical conductors, we wouldn’t require such big brains. And if we didn’t have such big brains, the neurons in our cortex wouldn’t have to make such perilous journeys from their place of origin to their final resting place, leaving us vulnerable to all manner of neurological disorders. The fact that even the neurons on the surface of our brain must migrate from generative zones deep in the brain is also an inefficient homology. Any decent electrical engineer would produce neurons closer to where they ultimately need to be.

Much of our brain wiring is also inefficient, because it was not designed from the ground up; it is, rather, a patchwork of repurposed elements and jury-rigged add-ons, what Gary Marcus has so aptly labeled “kluges.” These kluges extend to the bits of the brain we hold most dear, such as the circuits involved in language. One of the main organizing principles of the brain is called “neural reuse,” in which neural circuits that evolved to serve one function are recycled, repurposed, and redeployed for completely different ends during the course of evolution. Brains designed by an omnipotent God should be reverse engineerable; brains that are products of evolution, not so much.

But there is another factor that greatly complicates the evaluation of any proposed human cognitive adaptations: the huge role that culture plays in our cognitive lives. The self-domestication hypothesis purports adaptations that are biological, the product of natural selection. But culture plays a formative role in the development of all human cognitive capacities. Given the prodigious cultural forces that influence human cognitive development, it is no easy task to distinguish a purely biologically adaptive (as opposed to culturally adaptive) component in the development of complex human cognitive and emotional traits. Usually such attempts simply involve a search for “cultural universals,” which are supposed to implicate natural selection.8 But this inference is far from straightforward. Cultural universals can be universal for reasons other than natural selection. Conversely, some of the best evidence for active selection in humans comes from traits, such as lactose intolerance, that are not culturally universal.

For all of these reasons, many questions about human cognitive evolution may remain forever unanswered, by the standards of mainstream evolutionary biology, especially those concerning what past selection was for. We need to acknowledge at the outset that the self-domestication hypothesis may fall into this category.

This counsel of humility, given the obstacles just described, goes completely unheeded by many, especially those prone to making bold claims about human nature based on the slightest evidence that a trait is adaptive. From human ethology to sociobiology to evolutionary psychology, there has been an overwhelming tendency to blithely ignore the evidential standards of mainstream evolutionary biology. Evolutionary psychologists are in many ways the worst offenders; the assumptions that distinguish evolutionary psychology from its predecessors provide quite effective insulation from empirical assault.In lieu of the biological information required to apply the comparative method, evolutionary psychologists adopt a first-principles approach, in which they make assumptions about the human environment, usually an unspecified period of the Pleistocene, and then infer, through a process called reverse engineering, what natural selection “must have done to the human mind/brain.

see [part 1]

Domesticated: Evolution in a Man-Made World, Richard C. Francis, W. W. Norton, 2015

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Involving

One of the arguments in favor of analog audio, LPs, and vacuum tubes, is that an analog signal is closer to the real continuous acoustic waveform; that analog is a perfectly smooth wave, just like sound in air. Digital, in contrast, is broken up bits. The beautiful, smooth, continuous sound wave has been chopped to pieces and stacked together in jagged blocks. How could that possibly sound natural, or even good? Both of these beliefs rely on certain assumptions.

Assumption number one : Sound waves are smooth and continuous. Well. . , kinda, sorta, maybe. Air, the medium sound travels through, is not smooth and continuous. It’s a myriad of atoms and molecules floating around in space, bumping into each other—hardly smooth or continuous. Converting the sound wave into an electrical wave makes for an excellent analogy. The electrical wave is likewise individual electrons all jostling around interacting with each other in the medium of copper or silicon. It’s not exactly perfectly smooth and continuous either.

Analog reel-to-reel tape is made up of grains of magnetic molecules, rather large ones at that. If you know the basics of tape recording, you’ll know that wider tape, running at a faster speed makes for a higher quality recording. Cassette tapes, 1/8″ wide running at a snail’s pace of 1 7/8 inches per second, can’t hold a candle to a studio deck with 1″ tape running a 15 or 30 inches per second. The simple explanation is resolution, that is, the number of molecules holding the signal is 64 times greater on the 1″ tape. (Given both are four track—1″ is 8 times wider, and 15ips is 8 times faster, 8×8=64.) This allows for a stronger signal, wider dynamic range, wider frequency response, and less distortion in every way distortion can be measured—wow & flutter, harmonic, noise (tape hiss), etc., and yet it’s still not perfectly smooth.

Vinyl is subject to much of the same, plus more issues to deal with—groove depth and width, cutter and stylus size and shape, chemical makeup of the vinyl, friction, and variables associated with the shrinking radius from outside to inside grove. Add to this the mechanical elements—turntable, tonearm, cartridge—and you’ve got a chain of discontinuity, changes in medium and method of carrying the wave. Every change, every point of contact, entails a loss of information, loss of accuracy, loss of fidelity.

But the real deception comes from how we’ve constructed our conceptual models of analog and digital. The model of a continuous waveform is a way for us to describe and understand what’s happening in the air acoustically, or in a wire electrically. Discreet bits, 1 or 0, on or off, is how we understand digital. Neither is an exact picture. Both are only models of reality.

Assumption number two : Digital bits appear to be disconnected chunks—jagged pieces of the wave that are missing huge portions of information in between the sampled bits. It may seem that a mere forty-four-thousand-one-hundred bits per second is inadequate to represent an apparently infinitely smooth waveform, however forty-four-thousand samples per second is all that’s needed to encode a waveform up to 22kHz, frequencies beyond human hearing. It doesn’t have to be a perfectly smooth representation, because all the audible information is there. But the biggest deception of digital is that the playback is in bits. No, no one listens to digital bits. We listen to the analog reconstruction of the digitally encoded original analog waveform. Digital is simply a different way of representing (recording and storing) a sound wave. And because the sound is being encoded without mechanics imparting its grunge, or grains of magnetic oxides adding their own noise, or diamond styluses grinding across vinyl, digital is able to save the wave as clean and pure as the original signal fed to the analog-digital converter. And that digital code can be manipulated, controlled, copied, and recopied without adding noise or distortion as happens invariably at every step with analog processing. Digital is an audio (and video) miracle.

So, why are so many a’philes in love with LPs and tubes? Why do they categorically state that analog “blows digital out of the water, man? In a single word : involvement.

A couple of taps on a touch screen to cue up a digital file doesn’t compare to the ceremony of LP playback—pulling the 12″ album from the shelf, extracting the sleeved LP, carefully removing it from its inner liner, touching only on the outer edge and the label, placing it tenderly on the turntable’s platter, cleaning the surface, and gently, gently setting the tonearm on the spinning spiral. Oh, and the big album cover with artwork and text you can read by moonlight. One is involved, invested, even before a sound is heard. And don’t underestimate the investment, not only in ritual and time, but in the monetary resources required—analog costs more, much, much more. Then. . , there’s the sound.

There is something special about the sound of vinyl. It is not sterile. It’s full and rich. Full of resonances and rumble; rich in harmonics, surface noises, and crosstalk. It takes extra concentration to listen through the encompassing steamy warmth of LP colorations. Those extras hide details that our mind’s ear needs to fill in. The extra engagement, extra effort, makes LP listening more demanding, more involving. And when we fill in the missing pieces with our imagination, aaahhh, there’s a rainbow world of blooming, blushing beauty to behold. This brings us to valves. Vacuum tubes add an additional layer of harmonic and resonant color to the sound—and time, and effort, and cost. It’s no wonder why some people are so enamored with these quaint, antiquated technologies, and swear by them. Consequently, analog lovers are unable to get their ears around the clean, unembellished sound of digital. Digital requires no extra effort, no engagement, no imagination. It presents us with the complete, clear, crystalline details flat out—direct and raw—straight, no chaser.

With all that added color, there’s no way that analog, in any form, can deliver a more perfect waveform of the original music than digital can no matter how we model it, no matter how we hear it. It matters little that analog appears to be more akin to acoustic waves when sounds waves are in themselves granular. They don’t, in reality, exist as an infinitely continuous wave. And it doesn’t matter that digital is made of discreet bits because we don’t listen to bits. After all the processing a sound recording goes through, whether analog or digital, the final result, what we hear, is only the sound reproduced by the speakers.

Ultimately, one could argue, digital is, in realityquantum reality—closer to reality. At some point everything reduces to a quantum unit—energy, matter, gravity, space, and time.

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