Some random discussion on evolution...

Contradiction said:

Your points are red herrings whose purpose is to divert discussion to irrelevant issues.

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This may or may not be true, but your response looks as if you are simply avoiding answering - either because you cannot answer, or because you know your answers would be ineffectual.
So, if you wish your thesis to be given fair consideration you would be advised to address those points. I for one hesitate to engage in a discussion with someone who bolts at the first sign of adversity.

OldWiseGuy said:

It's one thing for a critter to grow bigger, smaller, or more hairy. It's quite another for it to change into something entirely different.

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How so? Most of a ape becoming human is just that. Bigger bodies, brains few other features and such.

loveofourlord said:

How so? Most of a ape becoming human is just that. Bigger bodies, brains few other features and such.

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How would that happen?

OldWiseGuy said:

How would that happen?

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Small continual modifications to whats already there, nothing complicated.

loveofourlord said:

Small continual modifications to whats already there, nothing complicated.

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In concert with environmental changes, so the theory goes.
Environmental changes are usually quite sudden whereas evolution is quite slow. How do you reconcile this?

OldWiseGuy said:

In concert with environmental changes, so the theory goes.
Environmental changes are usually quite sudden whereas evolution is quite slow. How do you reconcile this?

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Also continual adaptation and competition with other species.

In most cases climate change is pretty gradual, so that can open up new niches or variations of niches to species.

OldWiseGuy said:

In concert with environmental changes, so the theory goes.
Environmental changes are usually quite sudden whereas evolution is quite slow. How do you reconcile this?

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I suggest biology 101.

VirOptimus said:

I suggest biology 101.

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Why not Anatomy 101?

Chapter 1. Simple complexity.

The Anatomy of Movement

Almost all of behavior involves motor function, from talking to gesturing to walking. But even a simple movement like reaching out to pick up a glass of water can be a complex motor task to study. Not only does your brain have to figure out which muscles to contract and in which order to steer your hand to the glass, it also has to estimate the force needed to pick up the glass. Other factors, like how much water is in the glass and what material the glass is made from, also influence the brains calculations. Not surprisingly, there are many anatomical regions which are involved in motor function.

The primary motor cortex, or M1, is one of the principal brain areas involved in motor function. M1 is located in the frontal lobe of the brain, along a bump called the precentral gyrus (figure 1a). The role of the primary motor cortex is to generate neural impulses that control the execution of movement. Signals from M1 cross the bodys midline to activate skeletal muscles on the opposite side of the body, meaning that the left hemisphere of the brain controls the right side of the body, and the right hemisphere controls the left side of the body. Every part of the body is represented in the primary motor cortex, and these representations are arranged somatotopically — the foot is next to the leg which is next to the trunk which is next to the arm and the hand. The amount of brain matter devoted to any particular body part represents the amount of control that the primary motor cortex has over that body part. For example, a lot of cortical space is required to control the complex movements of the hand and fingers, and these body parts have larger representations in M1 than the trunk or legs, whose muscle patterns are relatively simple. This disproportionate map of the body in the motor cortex is called the motor homunculus (figure 1b).


Figure 1b: The motor homunculus in primary motor cortex. A figurative representation of the body map encoded in primary motor cortex. The section corresponds to the plane indicated in figure 1a. Body parts with complex repertories of fine movement, like the hand, require more cortical space in M1, while body parts with relatively simpler movements, like the hip, require less cortical space.

Other regions of the cortex involved in motor function are called the secondary motor cortices. These regions include the posterior parietal cortex, the premotor cortex, and the supplementary motor area (SMA). The posterior parietal cortex is involved in transforming visual information into motor commands. For example, the posterior parietal cortex would be involved in determining how to steer the arm to a glass of water based on where the glass is located in space. The posterior parietal areas send this information on to the premotor cortex and the supplementary motor area. The premotor cortex lies just in front of (anterior to) the primary motor cortex. It is involved in the sensory guidance of movement, and controls the more proximal muscles and trunk muscles of the body. In our example, the premotor cortex would help to orient the body before reaching for the glass of water. The supplementary motor area lies above, or medial to, the premotor area, also in front of the primary motor cortex. It is involved in the planning of complex movements and in coordinating two-handed movements. The supplementary motor area and the premotor regions both send information to the primary motor cortex as well as to brainstem motor regions.

Neurons in M1, SMA and premotor cortex give rise to the fibers of the corticospinal tract. The corticospinal tract is the only direct pathway from the cortex to the spine and is composed of over a million fibers. These fibers descend through the brainstem where the majority of them cross over to the opposite side of the body. After crossing, the fibers continue to descend through the spine, terminating at the appropriate spinal levels. The corticospinal tract is the main pathway for control of voluntary movement in humans. There are other motor pathways which originate from subcortical groups of motor neurons (nuclei). These pathways control posture and balance, coarse movements of the proximal muscles, and coordinate head, neck and eye movements in response to visual targets. Subcortical pathways can modify voluntary movement through interneuronal circuits in the spine and through projections to cortical motor regions.

The spinal cord is comprised of both white and gray matter. The white matter consists of nerve fibers traveling through the spine. It is white because the nerve fibers are insulated with myelin for faster conduction of signals. Like many other large fiber bundles, the corticospinal tract courses through the lateral white matter of the spine. The inside of the spinal cord contains gray matter, composed of the cell bodies of cells including motor neurons and interneurons. In a cross-section of the spinal cord, the shape of the gray matter resembles a butterfly. Fibers in the corticospinal tract synapse onto motor neurons and interneurons in the ventral horn of the spine. Fibers coming from hand regions in the cortex end on motor neurons higher up in the spine (in the cervical levels) than fibers from the leg regions which terminate in the lumbar levels. The lower levels of the spine therefore have much less white matter than the higher levels.

Within the ventral horn, motor neurons projecting to distal muscles are located more laterally than neurons controlling the proximal muscles. Neurons projecting to the trunk muscles are located the most medially. Furthermore, neurons of extensors (muscles that increase the joint angle such as the triceps muscle) are found near the edge of the gray matter, but the flexors (muscles which decrease the joint angle such as the biceps muscle) are more interior. It is important to note that a single motor neuron in the spine can receive thousands of inputs from the cortical motor regions, the subcortical motor regions and also through interneurons in the spine. These interneurons receive input from the same regions, and allow complex circuits to develop.

Figure 2: Cortical control of skeletal muscles.
Signals generated in the primary motor cortex travel down the corticospinal tract (green) through the spinal white matter to synapse on interneurons and motor neurons in the spinal cords ventral horn. Ventral horn neurons in turn send their axons (blue) out through the ventral roots to innervate individual muscle fibers. In this example, a signal from M1 travels through the corticospinal tract and exits the spine around the sixth cervical level. A peripheral motor neuron relays the signal out to the arm to activate a group of myofibrils in the bicep, causing that muscle to contract. Collectively, the ventral horn motor neuron, its axon, and the myofibrils that it innervates are called a single motor unit.

Each motor neuron in the spine is part of a functional unit called the motor unit (figure 2). The motor unit is composed of the motor neuron, its axon and the muscle fibers it innervates. Smaller motor neurons typically innervate smaller muscle fibers. Motor neurons can innervate any number of muscle fibers, but each fiber is only innervated by one motor neuron. When the motor neuron fires, all of its muscle fibers contract. The size of the motor units and the number of fibers that are innervated contribute to the force of the muscle contraction.

There are two types of motor neurons in the spine, alpha and gamma motor neurons. The alpha motor neurons innervate muscle fibers that contribute to force production. The gamma motor neurons innervate fibers within the muscle spindle. The muscle spindle is a structure inside the muscle that measures the length, or stretch, of the muscle. The role of the musclespindle in reflexes such as the knee jerk reflex will be reviewed in the Motor Systems Physiology section of this NeuroSeries. The golgi tendon organ is also a stretch receptor, but it is located in the tendons that connect the muscle to the skeleton. It provides information to the motor centers about the force of the muscle contraction. Information from muscle spindles, golgi tendon organs and other sensory organs are directed to the cerebellum. The cerebellum is a small grooved structure located in the back of the brain beneath the occipital lobe. This motor region is specifically involved when learning a new sport or dance step or instrument. The cerebellum is involved in the timing and coordination of motor programs. The actual motor programs are generated in the basal ganglia. The basal ganglia are several subcortical regions that are involved in organizing motor programs for complex movements. Damage to these regions result in spontaneous, inappropriate movements. The basal ganglia send output to other subcortical brain regions and the cortex.

Through the interaction of many anatomical motor regions, everyday movements seem effortless and more complex movements can be learned.

OldWiseGuy said:

Why not Anatomy 101?

Chapter 1. Simple complexity.

The Anatomy of Movement

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Sure, have you studied Anatomy 101?

VirOptimus said:

Sure, have you studied Anatomy 101?

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Enough to see that evolution is out of the question. Anatomy is the complexity I have referred to in other posts. Complexity that is clearly beyond the reach of evolution.

OldWiseGuy said:

Enough to see that evolution is out of the question.

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In other words, you have not.

I again suggest learning the facts.

VirOptimus said:

In other words, you have not.

I again suggest learning the facts.

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Anatomy study reveals that evolution is out of the question.

OldWiseGuy said:

Anatomy study reveals that evolution is out of the question.

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Haha, no.

The ToE is incredibly well-supported. If you understood it you would also understand why your ”argument” is so funny.

OldWiseGuy said:

Enough to see that evolution is out of the question. Anatomy is the complexity I have referred to in other posts. Complexity that is clearly beyond the reach of evolution.

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Your incredulity does not define biology.

pitabread said:

Your incredulity does not define biology.

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I don't think you and others understand just how complex biology is. It's well into the impossible range for evolution. You have waved away 99.9999999999 (plus or minus) percent of it even while presenting a 'complex' evolutionary picture.

Biology reveals creation, not evolution.

Contradiction said:

Your points are red herrings whose purpose is to divert discussion to irrelevant issues. The issues that are relevant here are:

A) Observational knowledge about the complete inability of evolution to create new and distinct functional structures

B) Reason for that inability, i.e. the ratio between changes that are biologically functional and those that are non-functional

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Your OP tries to make the above argument using examples based on human evolution and the long-term E.Coli experiment and then equate them to events like the Cambrian explosion which are many orders of magnitude larger in both time and scope.

Pointing out that flaw in the argument is hardly a red herring; it is a flaw in the core of your argument.

Well, it is not time that matters, but change. Change is the driving force of evolution. And the amount of change is directly associated with population sizes. Both, E.coli in Lenski's experiment and humans, have large population sizes. E.coli due to laboratory conditions and humans due to technological and agricultural innovations. So the amount of change in these two species may even be larger than it was in the entire biosphere of early Cambrian.

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What? If you're suggesting that a 30 year experiment using bacteria in test tubes should produce more evolutionary change than an entire planet's worth of organisms over millions of years, then I don't know what to tell you.

It's like claiming that a light bulb has more energy output than the Sun; that is just plain incorrect.

(Also, changes in populations over time is based on a number of factors. A larger population will have a slower time to fixation for new alleles whereas smaller populations have shorter times. Relative selection pressure is another factor; a population free of selective constraints may not undergo much evolutionary change over time versus a population under greater selective constraint. There is also the aforementioned discordance between changes to the genotype versus phenotype, especially if one is only concerned about morphological differences.)

In addition to that, current biodiversity on planet Earth is not out of the scope of scientific observation. Scientist study many different species and none of them have ever evolved some new and distinct functional structure. So, we have observed lot of change and have more then enough observational knowledge to conclude that the creation powers of evolution are zero.

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This is again where there appears to be a conceptual misunderstanding. Evolution does not just magically invent "new and distinct" structures. It modifies what came before it.

Using bird wings as an example, they are not completely novel structure. Rather they are modified vertebrate forelimbs and bear the evolutionary hallmarks of such in the underlying physical structure.

Same thing with various organs and other structural features of modern organisms.

No, I am stating the fact that computational capacity of the entire universe from its birth to its death is insufficient to overcome the ratio between changes that are biologically functional to those that are non-functional.

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This statement makes no sense.

Cars are arrangements of particles the same as biological organisms and therefore relevant to the discussion.

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Last time I checked, being an "arrangement of particles" didn't necessarily make non-living things relevant to a discussion of biology.

If you deny that, try to metabolize a specific substance with some random combination of carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur, which are six essential elemental ingredients from which all organisms are built.

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Evolution is not a purely random process though. It's a recursive process that builds on what came before it coupled with selective pressures based on relative fitness.

If you think that evolution is just randomly throwing basic elements together then you simply don't understand it at all.

OldWiseGuy said:

In concert with environmental changes, so the theory goes.
Environmental changes are usually quite sudden whereas evolution is quite slow. How do you reconcile this?

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That is only one aspect, there is the cheetah and the gazelle, the gazelle is fighting to avoid the cheetah the cheetah is fighting to hunt the gazelle so anything that benefits them both change over time, then add in all the things the cheetah and the gazelle are competing against, all the enviormental changes and so on. Yes a massive envoromental change plays one part, but so do many other things.

OldWiseGuy said:

I don't think you and others understand just how complex biology is. It's well into the impossible range for evolution. You have waved away 99.9999999999 (plus or minus) percent of it even while presenting a 'complex' evolutionary picture.

Biology reveals creation, not evolution.

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......

We do know how complex it is, you clearly dont!

OldWiseGuy said:

I don't think you and others understand just how complex biology is. It's well into the impossible range for evolution. You have waved away 99.9999999999 (plus or minus) percent of it even while presenting a 'complex' evolutionary picture.

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I don't think you understand what complexity is.

Biology reveals creation, not evolution.

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Why is there no scientific theory of creation then?