Natural selection has taken up shape

Gaurang said:
well I wanted to know his point behind falsification ofthis
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Disease is a good example. When a population suffers from disease, such as ebola, people with natural resistance survive. Over time we would expect to see larger numbers of people with natural resistance to ebola. Change in a gene pool over time is evolution.
 
origin said:
Of course. If in 100,000 years mankind is a small brained tree dweller, that would simply mean we evolved to that type of animal.
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Well, I would call that devolution to an earlier state.

Would you call the decay of a radioactive isotope evolution or devolution?
 
Write4U said:
I used the term merely to draw a distinction between the common understanding that evolution is a positive evolvement in the direction of more sophisticated skill and adaptation, whereas devolution is more of a devolvement in the direction of lesser skills and adaptive powers.
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The problem there is that that involves value judgments. Does a fish that loses its eyes devolve, even if its lateral line gets that much more sensitive? Many people would consider that devolution, since humans value vision. A bat might consider that evolution, since they are losing an unimportant sense and improving an important one. In reality all changes that make an organism more fit for an environment are evolution, even if it means that the organism loses structures or complexities that we consider "advanced" or "sophisticated."
 
billvon said:
The problem there is that that involves value judgments. Does a fish that loses its eyes devolve, even if its lateral line gets that much more sensitive? Many people would consider that devolution, since humans value vision. A bat might consider that evolution, since they are losing an unimportant sense and improving an important one. In reality all changes that make an organism more fit for an environment are evolution, even if it means that the organism loses structures or complexities that we consider "advanced" or "sophisticated."
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I agree with that. Devolution of one useless ability (cave dwelling fish do not need eysight) may be causal to the evolution of other more functional mechanisms, such as sonar.

Thus the discovery of dark caves which provided shelter and food by "sighted fishes" resulted in the devolution of the eye, but also resulted in the evolution of other (more functional) sensory abilities.

A perfect example is the "cuttlefish" which can blend with its envirionment, both in shape as well as color.
Remarkably, the cuttlefish is colorblind!
 
Write4U said:
I agree with that. Devolution of one useless ability (cave dwelling fish do not need eysight) may be causal to the evolution of other more functional mechanisms, such as sonar.
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That is not devolution, that is evolution. The different species of cave fish evolved to have no eyes since having eyes is a determent to their survival. For instance eyes are easily damaged by bumping into things and can become infected killing the fish. The lack of eyes increases the chances of the fish surviving. So this is an excellent example of what evolution is - adaptation to the environment, it is not devolution.

Devolution is survival of the least fit, which is absurd.
 
origin said:
That is not devolution, that is evolution. The different species of cave fish evolved to have no eyes since having eyes is a determent to their survival. For instance eyes are easily damaged by bumping into things and can become infected killing the fish. The lack of eyes increases the chances of the fish surviving. So this is an excellent example of what evolution is - adaptation to the environment, it is not devolution.

Devolution is survival of the least fit, which is absurd.
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No Origin, the cave fish HAS eyes, but they are no longer functional as normal eyes. They may still fill a function but it is no longer eyesight, there is no light in caves.
The caves were not their original habitat.
The Eyeless Socket
The Mexican tetra, Astyanax mexicanus, is a freshwater fish found mainly in the rivers throughout central and eastern Mexico, as well as in a few rivers in the United States. At some point in the fish's distant past, populations of A. mexicanus got trapped in pitch-black, underwater caves. In their new — and vastly different — habitats, the fish lost their pigmentation and their eyes, and became better able to store energy and detect changes in water pressure (to find prey and each other).
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http://io9.com/how-the-cavefish-los...Jewu2e_Ig.2&utm_referrer=http://www.bing.com/

I am not arguing that this not part of Evolution of species in the overall scope, but there are instances where a previous effective ability has no longer a purpose, thus that ability devolves and is replaced by an evolving substitute. Similar to an unstable complex element that devolves into a simpler (but stable) element, releasing (requiring less) energy in the process

It is really a minor point, IMO.
 
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Um... the very first sentence of that link states that the fish has no eyes.
 
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Write4U said:
The point is that they DID have eyes, but not anymore because they were useless in their new environment.
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No shit that is the point - it's called EVOLUTION. My objection was you calling evolution, devolution.
 
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Write4U said:
I am not arguing that this not part of Evolution of species in the overall scope, but there are instances where a previous effective ability has no longer a purpose, thus that ability devolves and is replaced by an evolving substitute. Similar to an unstable complex element that devolves into a simpler (but stable) element, releasing (requiring less) energy in the process
It is really a minor point, IMO.
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So in your opinion the evolution of fish to land animals is devolution! The fish lost there fins and replaced them with limbs for walking. It is just silly and incorrect to be using the term devolution for evolution.
 
origin said:
So in your opinion the evolution of fish to land animals is devolution! The fish lost there fins and replaced them with limbs for walking. It is just silly and incorrect to be using the term devolution for evolution.
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One of the assumptions of evolution is that there is no sense of direction, so two steps backwards or on one step forwards is still called evolution. The no sense of direction assumption is connected to a randomness assumption, with all sides of a six sided dice will be considered the same, even though they are numbered 1, 2,3,4,5,6.

In many people's mind, who think in terms of order, 1 comes before 2, which comes before 3. They think in terms of increasing complexity and sophistication. One has to roll 1 before 2.


To go from sea to land, requires a number of changes in the body. First and foremost, the critter has to be able to breath out of the water. Nature has to provide a way to make to make this a needed selection. If a fish developed lungs, but never leaves the water, it will drown. To make this selection nature has to get this critter to leave the water.

One scenario for nature making it necessary to select the lung fish, is the seasonal drying up of the water pools, so the fish have to deal with being forced to breath in shallow water or half out of the water. This natural condition may result in the selection of fish with better gills or fish with supplemental system lung system that does not need water to breath. When the drought comes, these new fish last the longest, and breed the future.

Since these are successful and begin to multiply, as the ponds and pools shrink, the new problem is overcrowding. This impacts the gill fish more leaving the gill-lung fish being selected. As they increase their numbers again overcrowding problems appears with locomotion into other pools, the key advantage needed for selection.

My contention is the environmental stress will stress the body and increase the need to change so the needed selections appear with enough frequency to assure survival of life. Lungs will not appear as often, as mutations in fish that never leave the water. This who are stressed will see this happen more often; chemical adaptation.
 
wellwisher said:
One of the assumptions of evolution is that there is no sense of direction, so two steps backwards or on one step forwards is still called evolution. The no sense of direction assumption is connected to a randomness assumption, with all sides of a six sided dice will be considered the same, even though they are numbered 1, 2,3,4,5,6.

In many people's mind, who think in terms of order, 1 comes before 2, which comes before 3. They think in terms of increasing complexity and sophistication. One has to roll 1 before 2.


To go from sea to land, requires a number of changes in the body. First and foremost, the critter has to be able to breath out of the water. Nature has to provide a way to make to make this a needed selection. If a fish developed lungs, but never leaves the water, it will drown. To make this selection nature has to get this critter to leave the water.

One scenario for nature making it necessary to select the lung fish, is the seasonal drying up of the water pools, so the fish have to deal with being forced to breath in shallow water or half out of the water. This natural condition may result in the selection of fish with better gills or fish with supplemental system lung system that does not need water to breath. When the drought comes, these new fish last the longest, and breed the future.

Since these are successful and begin to multiply, as the ponds and pools shrink, the new problem is overcrowding. This impacts the gill fish more leaving the gill-lung fish being selected. As they increase their numbers again overcrowding problems appears with locomotion into other pools, the key advantage needed for selection.

My contention is the environmental stress will stress the body and increase the need to change so the needed selections appear with enough frequency to assure survival of life. Lungs will not appear as often, as mutations in fish that never leave the water. This who are stressed will see this happen more often; chemical adaptation.
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Mostly correct. It has been noted that fish who are adapted to shallow pools, when stressed by being forced to live with minimal water, will grow stronger muscles and bones in the course of "walking" around not supported by water, thus increasing their fitness in such an environment.
http://www.popsci.com/article/science/if-fish-grows-land-will-it-learn-walk
 
wellwisher said:
One of the assumptions of evolution is that there is no sense of direction, so two steps backwards or on one step forwards is still called evolution. The no sense of direction assumption is connected to a randomness assumption
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No, it is not connected to randomness. It is simply because organisms adapt to the environment. So if animals are adapting to an environment how in the hell could there be a step back as you call it. You cannot step 'backwards' (or forward for that matter!) if you are simply adapting to an environment.
 
origin said:
So in your opinion the evolution of fish to land animals is devolution! The fish lost there fins and replaced them with limbs for walking. It is just silly and incorrect to be using the term devolution for evolution.
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That is not an accurate comparison. The fish's fins evolved into limbs, thus it did not lose its fins, it modified them for walking, evolution in its purest form.

The cave fish is unique in that it used to have sighted eyes, which "degenerated" until the fish no longer had any eyes at all, but could still detect changes in light through its pineal gland, which is located in the brain. The eye socket is now an empty space containing no eyeball and has protective skin over the empty socket.

Thus the previous headline "Eyeless socket". Apparently this occurred through degenerative mutations which (in this case) proved to be a better adaption to darkness, rather than wasting energy on the development of useless eyes.

The word I should have used is "degeneration", not "devolution" as I posted for convenience, but to me that does not adequately explain the process of completely losing a previously evolved asset. A linguistic anomaly.

As English is not my first language, I usually research an important word for its exact definition and meaning, before posting. In haste I neglected to do that here and it seemed quite natural to me that the antonym for "evolve" should be "devolve". The word does exist, just not as it pertains to the grander all-encompassing form of the phrase "natural evolution".

I find that a curious twist, but I understand the reason. Thus I'll concede that my use of "devolve" was incorrect, albeit more correct than "degenerate to the point of disappearance", IMO.
Blind Fish Still Able to 'See',
The blind cave-dwelling form of the Mexican tetra (Astyanax mexicanus) evolved from surface-dwelling ancestors whose eyes degenerated after the fish shifted their habitat into complete darkness a million or more years ago. These albino cavefish dwell today in freshwater caves in northeastern Mexico, with skin growing over their now useless eyes.
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http://www.livescience.com/9555-blind-fish.html
 
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Write4U said:
That is not an accurate comparison. The fish's fins evolved into limbs, thus it did not lose its fins, it modified them for walking, evolution in its purest form.

The cave fish is unique in that it used to have sighted eyes, which "degenerated" until the fish no longer had any eyes at all, but could still detect changes in light through its pineal gland, which is located in the brain. The eye socket is now an empty space containing no eyeball and has protective scales over the empty socket.

Thus the previous headline "Eyeless socket". Apparently this occurred through degenerative mutations which (in this case) proved to be a better adaption to darkness, rather than wasting energy on the development of useless eyes.

The word I should have used is "degeneration", not "devolution" as I posted for convenience, but to me that does not adequately explain the process of completely losing a previously evolved asset. A linguistic anomaly.

As English is not my first language, I usually research an important word for its exact definition and meaning, before posting. In haste I neglected to do that here and it seemed quite natural to me that the antonym for "evolve" should be "devolve". The word does exist, just not as it pertains to the grander all-encompassing form of the phrase "natural evolution".

I find that a curious twist, but I understand the reason. Thus I'll concede that my use of "devolve" was incorrect, albeit more correct than "degenerate", IMO.
http://www.livescience.com/9555-blind-fish.html
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I can live with that.

I find it annoying that English is not your first language and yet in general you write better than I do!;)
 
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