Illogical Component of Evolution Theory???

[TruthSeeker]

There's one thing about evolutionary theory that bugs me. I just don't see how it could work. I will attempt to compose my question in this thread.

Here's the deal. Evolution states that it takes a long time for an organism to adapt and change, when introduced into a new environment. I don't get it. How come the organisms don't die?

Here's an example. Send an organism that could not survive in Mars to Mars. Now what? Even if you send a gazillion of them to Mars, they would simply ALL DIE! Even if one or two would have a very little difference that could make them survive for a little while, how would the adapt fast enough to reproduce and survive in the planet?

Here's another scenario. An environment suddenly changes. How can the organisms survive if they adpat so slowly.

The point is.... why does evolution state that it takes millions of years for an organism to adapt to an environment which doesn't allow the survival of such organism in the first place!? Wouldn't it be more logical to assume that such adaptations would occur at a faster rate? :shrug:

 

[Fraggle Rocker]

Most mutations do die off. That's why species evolve so slowly. It can take tens of millions of years for a mutation to arise that has enough viability to survive long enough to not only reproduce but to establish a population. If this were not the case, the earth would be overrun with a chaotic mixture of species and the individuals would be lucky to find others like themselves.

As I've pointed out on these boards before, the innumeracy that has taken hold of America, and to a lesser extent other countries, makes our people incapable of comprehending processes that take place over long periods of time.

To answer your question about Mars, yes it's very likely that any Earth-adapted organism would die on Mars. There may be organic residue in its soil left over from a biosphere that died off a billion years ago, but it might not be made out of the same kind of "organic" molecules that we have on Earth. Mars might have evolved silicon-atom base life instead of carbon-atom based life. Organisms from Earth could not extract any nutrition from what we could call "hydrosilicons" as opposed to "hydrocarbons." We'd probably have to establish an entire miniature ecosystem on Mars before we'd have a good chance of it surviving.

As to your question about sudden changes in the environment... That is in fact not what happens. Even ice ages take hundreds or thousands of years to transform a region. That's not necessarily long enough for new species to evolve but it's long enough for existing species to adapt by mutation. Humans, for example, have migrated to every climate zone. The ones who ended up in arctic regions have very little melanin in their skin, which allows them to absorb sunlight and manufacture vitamin A. The ones who stayed closer to the equator have lots of melanin, which protects them against sunburn. It only takes a couple of thousand years for a population to develop darker or lighter skin, through the simple mechanism of survival of the fittest. The genes for more or less melanin are out there, it's just a matter of which combination enhances the chances of survival to breeding age.

The ecosystem does not change nearly as quickly as you hypothesize, and it gives mutation and other mechanisms such as genetic drift plenty of time to work. We're used to seeing the effects on the ecosystem of our own efforts, and those are indeed catastrophic. Species are becoming extinct at an alarming rate because they can't adapt to their new environment, and new species cannot arise rapidly enough to replace them. The Earth's biodiversity is shrinking. The situation is not quite as dire as I make it seem; the Earth will recover if we come to our senses soon enough and there is evidence that this may actually happen. For example, we have almost reversed the net decrease in forested land, although the reestablishment of forest land is happening in places like North America, rather than places like South America where it is more needed.

 

[James R]

Here's the deal. Evolution states that it takes a long time for an organism to adapt and change, when introduced into a new environment. I don't get it. How come the organisms don't die?

Many do. If they can't adapt, organisms die. 99%+ of all species that have ever existed on Earth are now extinct, for one reason or another.

Here's an example. Send an organism that could not survive in Mars to Mars. Now what? Even if you send a gazillion of them to Mars, they would simply ALL DIE! Even if one or two would have a very little difference that could make them survive for a little while, how would the adapt fast enough to reproduce and survive in the planet?

Depends what the organisms were. For example, bacteria can adapt quite quickly in some circumstances, and there are A LOT of them.

The point is.... why does evolution state that it takes millions of years for an organism to adapt to an environment which doesn't allow the survival of such organism in the first place!?

You're assuming that organisms are somehow plonked into pre-existing hostile environments. In fact, there are rarely harsh boundaries between neighbouring environments. Rather, there are usual gradual transitions and border areas. You don't go from dense rainforest to arid desert at some country-like border. Instead, dense rainforest shades to light rainforest, to perhaps grasslands, then to desert. A species adapted to the dense rainforest might gradually expand or change its range over many years, so that eventually it becomes a desert dweller. It doesn't suddenly jump out of the rainforest and move to the desert in one step.

 

[Idle Mind]

You're assuming that organisms are somehow plonked into pre-existing hostile environments. In fact, there are rarely harsh boundaries between neighbouring environments. Rather, there are usual gradual transitions and border areas. You don't go from dense rainforest to arid desert at some country-like border. Instead, dense rainforest shades to light rainforest, to perhaps grasslands, then to desert. A species adapted to the dense rainforest might gradually expand or change its range over many years, so that eventually it becomes a desert dweller. It doesn't suddenly jump out of the rainforest and move to the desert in one step.

To expand on this, the environment at which an organism lives normally takes a long time to change into another type of environment, so the organism doesn't need to adapt instantly.

 

[TruthSeeker]

Ok, so I guess the environment changes only fast enough to ALMOST kill everything... LOL!!!

Are we always on the edge of extinction?

Btw, it may seem a long time to you, but in fact, those are very quick changes compared to the age of the universe....

 

[CharonZ]

I think one of the best examples of extreme changes is the increase of oxygen in the atmosphere when the first photosynthetic organisms arose. Earlier there the bacteria had no resistance against oxygens because the atmosphere was essentially anoxic, however when photosynthesis evolved the produced oxygen rapidly killed off the majority of organisms. Of course the oxygen level only rose slowly and those that were already somewhat resistant could adapt to it, but the rest either died or were confined to anoxic habitats.

In general one can only expect a adaptation to certain stresses if there is already a structural basis to which the organism can adapt to. In the above example it was the presence of certain enzymes that were not dedicated to detoxification of oxygen radicals (as prior there was no oxygen present) but nonetheless could relieve the oxidative stress somewhat. Only then do selective pressures select for certain traits and do not completely eliminate the population.

 

[TruthSeeker]

I think one of the best examples of extreme changes is the increase of oxygen in the atmosphere when the first photosynthetic organisms arose. Earlier there the bacteria had no resistance against oxygens because the atmosphere was essentially anoxic, however when photosynthesis evolved the produced oxygen rapidly killed off the majority of organisms. Of course the oxygen level only rose slowly and those that were already somewhat resistant could adapt to it, but the rest either died or were confined to anoxic habitats.

In general one can only expect a adaptation to certain stresses if there is already a structural basis to which the organism can adapt to. In the above example it was the presence of certain enzymes that were not dedicated to detoxification of oxygen radicals (as prior there was no oxygen present) but nonetheless could relieve the oxidative stress somewhat. Only then do selective pressures select for certain traits and do not completely eliminate the population.

Now THAT answers my question. LOL!! Thank you.

 

[linscomb]

In general - organisms do not need to adapt quickly because the environment does not tend to change quickly. If it did we would not have described the ecosystems (it would be an exercise in futility). Organisms do not "adapt" at all unless there is a selective force at work.

 

[Buckaroo Banzai]

There's one thing about evolutionary theory that bugs me. I just don't see how it could work. I will attempt to compose my question in this thread.

Here's the deal. Evolution states that it takes a long time for an organism to adapt and change, when introduced into a new environment. I don't get it. How come the organisms don't die?

Here's an example. Send an organism that could not survive in Mars to Mars. Now what? Even if you send a gazillion of them to Mars, they would simply ALL DIE! Even if one or two would have a very little difference that could make them survive for a little while, how would the adapt fast enough to reproduce and survive in the planet?

"Evolution" does not say something like "drown generations after generations of a packs of dogs into aquariums, and eventually you will see a dog-fish".

It is far more subtle, like some "generic dog-like" populations slowly departing from each other and becoming wolves, coyotes, foxes, bears. If you retrocede further back in time, you would be in the split of caniforms (the "family" of dogs) and feliforms (cats), and they still are on both sides somewhat alike: weasels on the dog side, mongooses on the cat side... then you go back to some generic mammal and so on.

Almost nowhere in the whole history of evolution there are such drastic adaptations to whole new, "alien"-like environments.

Here's another scenario. An environment suddenly changes. How can the organisms survive if they adpat so slowly.

Again, most of envirommental change is not quite so dramatic that would require a dog to evolve into a fish or something. And, actually, whatever environmental change that is too much drastic to a population to adapt, will make these populations go extinct.

The point is.... why does evolution state that it takes millions of years for an organism to adapt to an environment which doesn't allow the survival of such organism in the first place!? Wouldn't it be more logical to assume that such adaptations would occur at a faster rate? :shrug:

Actually to say that the evolution of adaptations "takes millions of years" is not quite precise, it's just some sort of common sense saying, meaning that you won't see the next generation of some fish species crawl out of the water and walk as if it were already a perfectly terrestrial animal. Most of the time, the species will remain what they are, with minor changes, barely regarded as "evolutionary" change.

And evolutionary changes/adaptations can occur somewhat "fast" every now and then. It is yet nothing like a lizard egg hatching with a chicken inside, however, but again, the "fox-like into coyoye, wolf and maned-wolf" degree.

And, despite of being "fast", it would still take some generations of the species to become widespread, it does not appear instantly all over the population (but it may be already somewhat widespread even before the environmental change that would benefit/"require" the change occurs, since the origin of mutation is not triggered by the need for adaptation), but does not take millions of years.

 

[linscomb]

Punctuated equilibrium: Most of the time the organism is comparatively stable - no sudden changes. This "equilibrium" is interrupted by periodic but stochastic events that force the organism to undergo relatively rapid change. The change would be rapid from a comparative sense only.

Gradualism: Organisms are always accumulating tiny genetic changes that, when taken over vast periods of time, can add up to something quite different than what one started with.

The truth? As is usual - a likely mixture of both. No truth. Just more questions...

 

[Buckaroo Banzai]

This is a tricky issue.

Punctuated equilibrium does not opposes gradualism; it is a "case-specific" alternative for phyletic gradualism. But Punctuated equilibrium is itself ["just"] gradualist.

Phyletic gradualism, punctuated gradualism and punctuated equilibrium are inferred patterns of long-term evolutionary change.

Phyletic gragualism is when, all along the existence of a species, it is supposed to have changed a little sightly bit all the time, somewhat splitting in another population, and both slowly diverging all along the existence of their lineages.

(This term was coined together with punctuated equilibrum, in the same paper, if I'm not mistaken. It is not like it was the prior "theory", to be replaced with the newcomer PE, as it is often pictured. Both aren't even quite "theories", but more "patterns", and more or less implicitly or explicitly acknowledged before, and mechanisms that would made any of them possible were known before as well).

Punctuated equilibrium is when, instead of this pattern of subtle morphological "skew", most of the time, populations remained relatively stable; eventually changing comparatively "suddenly" - speaking in geological time frames, which is not really sudden at all, but gradual.

Punctuated gradualism is a middle ground between both patterns; somewhat "steady" change, with eventual abrupt "acceleration".


Different teams of scientists will sometimes interpret the same data as fullfilling a different pattern, and none of these patterns really requires something radically different, new, to exṕlain "what is really happening", the mechanism of evolution. It would be just minor calibration of mechanisms, such as, how much a large population assure the stability of the morphology of the populations, versus how much it is susceptible to be altered by relatively frequent crossbreeding with peripheral populations or even to the spread of variation of the insiders of the mainstream. These things will probably depend on many variables that will differ from species to species, to different classes of organisms. There can be a pattern that is more frequent overall, but I would not be able to tell which it would be.


"Just" gradualism opposes not to punctuated equilibrium but to saltation[ism]. Gradual, mundane, variation versus more abrupt change in one generation. I think that originally the latter was held as something very drastic, miraculous, such as a bird hatching from a lizard's egg.

This sort of thing certainly does not happen, the closest things that can happen are things like an eventual weirdo with "exceptionally" longer or shorter legs (like a basset hound, for instance; could be no legs at all, sometimes, perhaps it was what happened at some point with the whale ancestors), or extra bodily segments (even extra legs, in the case of arthropods), or a "atrophied" wing, or a above-average proneness to muscular (or weak) physical built. This level of changes can be debated as being classifiable as either "gradual" or "[weak] saltation", but then it's just semantics.