Friday, 22 March 2013

Unintelligently Designed Brain

You have to hand it to the 'Intelligent Designer'; it's never slow to use a complex design when a simple one would do, or an inefficient design when a more efficient one is available. Ironically, the human brain, for all it's complexity and for all the capability it has given to humans, is an example of inefficient design and unnecessary complexity. Far from being an argument for intelligent design, the human brain is, as you would expect of an evolved organ, a wonderful example of unintelligent design.

The brain is basically a biological computer with millions, billions, even, in the case of the human, elephant and dolphin brain, maybe hundreds of billions of neurological connections which act like computer logic gates. Briefly, logic gates perform binary (or Boolean) logic. Normally a logic gate has two inputs and an output so, according to the type of gate, two input signals can be processed to produce a single output signal, which can then form one of the inputs of another logic gate, and so on.

This isn't important to my point and is just for background, but the six most important types of logic gate are:
OR: (C = A or B). C = 1 if either A or B is 1, or if both A and B are 1.
AND: (C = A and B). C = 1 if and only if both A and B are 1.
NOT: (C = not A). C = 1 if A is 0, C = 0 if A is 1. Note: In this case there is no B input.
XOR: (C = A xor B). C = 1 if A or B is 1 but 0 if both are 1.
NOR: (C = A nor B). C = 0 unless A and B are both 0.
NAND: (C = A nand B). C = 1 unless A and B are both 1.
In a modern computer these gates work at nanosecond speeds or faster so that even the computers inside you laptop, ipad or smart phone are capable of millions or billions of calculations per second. They work with tiny electric currents, in other words, electrons moving at the speed of light. The only problem, and one of the limitations of microprocessor power, is that with all that energy exchange going on in such a small space, the heat produced can be enormous, hence the cooling fan, etc.

Computers communicate with their peripheral devices, and with the outside world like the Internet, with electrical signals, again relying on near light speed electrons flowing through conductors. All of the components of a computer and a computer system, and even a vast computer network like the World Wide Web, are perfectly natural materials, of course, just very pure and very precisely ordered, but surely nothing beyond the capability of an omnipotent god.

So, given basically the same engineering problem, how did the 'Intelligent Designer' solve the need for a communications systems and a central processor?

Probably with one of the worst kludges you can imagine. A kludge is design-speak for anything which works well enough, no matter how inefficiently or inelegantly. A sort of "It'll do!", or "Near enough is good enough!" approach to design.

First a little bit about neurones and how a signals are conveyed by a neurones to and from sense organs or from one neurone to another:
A typical neuron is divided into three parts: the soma or cell body, dendrites, and axon. The soma is usually compact; the axon and dendrites are filaments that extrude from it. Dendrites typically branch profusely, getting thinner with each branching, and extending their farthest branches a few hundred micrometres from the soma. The axon leaves the soma at a swelling called the axon hillock, and can extend for great distances, giving rise to hundreds of branches. Unlike dendrites, an axon usually maintains the same diameter as it extends. The soma may give rise to numerous dendrites, but never to more than one axon. Synaptic signals from other neurons are received by the soma and dendrites; signals to other neurons are transmitted by the axon. A typical synapse, then, is a contact between the axon of one neuron and a dendrite or soma of another. Synaptic signals may be excitatory or inhibitory. If the net excitation received by a neuron over a short period of time is large enough, the neuron generates a brief pulse called an action potential, which originates at the soma and propagates rapidly along the axon, activating synapses onto other neurons as it goes.

Action potentials are generated by special types of voltage-gated ion channels embedded in a cell's plasma membrane. These channels are shut when the membrane potential is near the resting potential of the cell, but they rapidly begin to open if the membrane potential increases to a precisely defined threshold value. When the channels open, they allow an inward flow of sodium ions, which changes the electrochemical gradient, which in turn produces a further rise in the membrane potential. This then causes more channels to open, producing a greater electric current, and so on. The process proceeds explosively until all of the available ion channels are open, resulting in a large upswing in the membrane potential. The rapid influx of sodium ions causes the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate. As the sodium channels close, sodium ions can no longer enter the neuron, and they are actively transported out of the plasma membrane. Potassium channels are then activated, and there is an outward current of potassium ions, returning the electrochemical gradient to the resting state. After an action potential has occurred, there is a transient negative shift, called the afterhyperpolarization or refractory period, due to additional potassium currents. This is the mechanism that prevents an action potential from travelling back the way it just came.

In animal cells, there are two primary types of action potentials, one type generated by voltage-gated sodium channels, the other by voltage-gated calcium channels. Sodium-based action potentials usually last for under one millisecond, whereas calcium-based action potentials may last for 100 milliseconds or longer. In some types of neurons, slow calcium spikes provide the driving force for a long burst of rapidly emitted sodium spikes. In cardiac muscle cells, on the other hand, an initial fast sodium spike provides a "primer" to provoke the rapid onset of a calcium spike, which then produces muscle contraction.
So, basically, a signal is transmitted along a nerve, not by simply whizzing electrons along a conductor but by a complicated process involving a flow of charged ions across the cell membrane, with this 'wave of depolarization' flowing sedately along the cell membrane, or jumping from one node to another, depending on the fibre, and then having to actively pump the ions back again against a potential gradient, so using energy and during which the nerve is briefly 'refractory' and unable to fire again. The result of this is that signals are processed and propagated through nerves about a million times more slowly than in a modern computer.

Now, when the signal needs to escape from the end of the neurone to activate a muscle, stimulate an excretory cell, or just to be passed on to the next neurone in the sequence, whereas an electrical conductor would just need to be touching at the point of contact, the unintelligent designer has come up with another gloriously complex kludge which works, but which only needs that complexity in the first place because of the solution employed. Consequently it slows transmission down considerably and entails a huge overhead in terms of metabolic input and energy requirement. It is a small gap called a synapse.
Synapses are essential to neuronal function: neurons are cells that are specialized to pass signals to individual target cells, and synapses are the means by which they do so. At a synapse, the plasma membrane of the signal-passing neuron (the presynaptic neuron) comes into close apposition with the membrane of the target (postsynaptic) cell. Both the presynaptic and postsynaptic sites contain extensive arrays of molecular machinery that link the two membranes together and carry out the signaling process. In many synapses, the presynaptic part is located on an axon, but some presynaptic sites are located on a dendrite or soma. Astrocytes also exchange information with the synaptic neurons, responding to synaptic activity and, in turn, regulating neurotransmission.
A couple of problems with synapses are that, apart from it's slowness, a neurone can become depleted of it's transmitter substance and become fatigued and, unless the released transmitter substance is quickly deactivated, the synapse won't be ready for the next signal, so a set of enzymes are needed to deactivated them, all needing to be manufactured and replaced, and all needing energy and adding to the general inefficiency.

Why did evolution 'use' this inefficient, slow and kludgey method? Because it had no choice, not having had any say in the matter. Evolution by natural selection is not a planned process and can only work on what is available. It is also impossible for it to scrap a design and start anew, as an intelligent designer would. Evolution only had cells with which to work and the only way to make a cell 'excitable' is with the flow of charged ions across a membrane. And it worked well enough. Just like the qwerty keyboard on our laptops, smart phones and computer keyboards, we are now stuck with it, with all its inefficiency.

And this has meant that, to evolve a brain large enough to have the processing power to give humans the advantage such a brain gave us once we had evolved a bipedal gait, our babies are born with already large heads, which adds another layer of difficulty to the human birth process, meaning that our babies are born especially under-developed needing a long period of parental care, so creating the conditions and opportunity for evolution by natural selection to evolve human cultures.

Of course, as you would expect, evolution has made do and refined the process of neuro-transmission as well as possible within the limits of what is possible, and even taken advantage of some of the opportunities the system presents, like the ability to have an inhibitory feed-back mechanism to, for example, allow the knee-jerk reflex to fire just once and not continually re-fire as the thigh muscles are stretched again as the lower leg drops back.

And almost unbelievable, this gloriously kluge-ridden, clunky system has, by evolution by natural selection, given rise to a fantastic organ like a brain, but no intelligent designer would have gone about it in that hugely inefficient way when simple conductors, logic gates and light-speed electrical conduction were all readily available to it. The glorious thing about evolution is not always the elegance and simple efficiency of its 'designs', but how it gets there in the end.

Unintelligent design gave us the human brain. The intelligence that made available to us, after 13 billion years of evolution, has allowed us to design a hugely more efficient and faster design called the microprocessor in a little over a hundred years since we understood electricity well enough to make it usable, and so we now have the Internet, where I can find out the information in this blog and present it for you to read.

Share on Twitter.

5 comments :

  1. Not to mention the design flaw whereby the myelin sheath covering the axion becomes damaged and the person slowly loses the ability to function--the condition commonly known as Multiple Sclerosis.

    ReplyDelete
  2. What do you mean in your last paragraph by suggesting it's intelligence that allows us to create microprocessors? We created microprocessors because the laws of physics required us to do so. All of history is a cascade of causes and effects. Are you suggesting there's something going on inside the extra slow biological brain of humans that transcends the laws of nature?

    ReplyDelete
    Replies
    1. You'll need to explain how microprocessors were invented by physics and no intelligence was involved. You'll also need to explain why you think human intelligence transcends the laws of nature.

      Good luck.

      Delete
    2. I suppose this gets at what intelligence is. It seems to me that talking about such things as intelligence and design only makes sense if one believes our universe is something other than a very large number of subatomic particles interacting according to some laws of nature. Maybe this is a disagreement over definitions, but it seems to me that unless something behaves contrary to what natural laws would compel, we cannot count that behavior as evidence of intelligence.

      So, since humans came about without intelligence and without design, and since we lack free will and are completely bound by the natural laws, anything we produce is simply a result of physical laws. Computers were no more invented than were humans or the universe itself.

      Delete
    3. All that is needed for a cause-effect chain to become a design process is a self-monitoring feed-back loop, able to modify the cause and/or effect and direct it towards a desired outcome, turning it into an iterative, self-modifying process. None of that need involve anything other than perfectly natural material events.

      Delete

Obscene, threatening or obnoxious messages, preaching, abuse and spam will be removed, as will anything by known Internet trolls and stalkers or by known sock-puppet accounts.

A claim made without evidence can be dismissed without evidence. Remember: your opinion is not an established fact unless corroborated.

ShareThis

Related Posts Plugin for WordPress, Blogger...
Web Analytics