evolution #2

[michel123456]

I was a kind of bored and got reading some stuff in this evolution area.

I think evolution is misunderstood. (my opinion)

As a read threads here, it seems that the concept of evolution is that of a conjecture where all species (including plants) develop along a line from simple living beings into more sophisticated & adapted ones.

It is a part of the conjecture, but IMO it is not the whole story. At each moment of the living Earth history, the whole biosphere must have worked as an interlace of relations between species, a net in constant dynamic equilibrium.

If a specie is not adapted to its environnement, it is believed (as I read here around) that evolution is supposed to drive this specie into more adaptatation. But it can also drive this specie to extinction. Not because the specie was "bad formated', but because environemental conditions change.

You can be a wonderful specie and suddenly disappear because your place will be, bit by bit, set at the edge of the net. At some point, a little push will set you out. Some other specie can remain in the eco-system for million of years, never reaching the edge of the net, and never falling out.

 

So, IMO evolution is not always a procedure going from simple to complicated. Simple organisms can evoluted or can disapear, and so for complicated organisms.

As a resume, i believe that evolution don't work always for better. It can also drive to extinction.

[Sisyphus]

Evolution does not really drive towards more sophisticated or complex forms, except incidentally. The evolutionary pressure is entirely towards propagating one's genes in the most successful means possible in the present environment. Sometimes the efficiency of simplicity outweighs the advantages of complexity. Some of the simplest organisms are arguably the most "successful" of all.

 

It's not really possible for a species to "evolve" into extinction, by definition. A species that goes extinct due to a changing environment has just failed to evolve quickly enough. Not "improve" or "become more sophisticated," but just adapted to propagate genes in the present environment. It is true that some species are adapted to more specific environments than others, and thus tend to be more vulnerable to environmental change.

[CharonY]

The OP misunderstands several concepts of evolution. However I wills start with

has just failed to evolve quickly enough

.

 

This is not entirely accurate, either. They did not adapt sufficiently to survive, maybe, but a quicker evolution (i.e. a more rapid change in the gene pool) does not necessarily increase fitness.

 

Now regarding

the concept of evolution is that of a conjecture where all species (including plants) develop along a line from simple living beings into more sophisticated & adapted ones

 

This is, as mentioned above not true. While one can trace the history of more complicated organisms all the back to the simplest ancestors, it does not mean that evolution is the process from simple to complex as already mentioned. I blame the tree drawings of evolution or maybe the sketch where apes morph into humans for this common misconception.

[pioneer]

Evolution works under the assumption that the aqueous and protein grids within cells (membranes and cytoplasm) can not tweak the DNA via cause and effect with the environment. Rather, it assumes changes in the DNA are detached from the rest of the cell and occur randomly. I tend to believe the DNA is tweaked by the rest of the cell. This allows life to keep its finger on the pulse of the environment and adapt as needed.

 

One line of reasoning that supports cause and effect, is if we assume random changes in the DNA, aren't there more things that can go wrong, than right, since random changes not only means improvements but also regressions. Random means the good genetic stuff, is also under random change into worse.

 

The parallel scenario that random creates is that selective advantage can be connected to avoiding bad random genetic changes. If the all the rest of the animals get more defects, due to random, and you get fewer, one has a selective advantage and therefore be called more evolved.

 

However, evolution is usually expressed in terms of something positive, which gives selective advantage. That can not be random, since advantage implies is a sense of direction, relative to what could happen if we randomly tweaked genes; good and bad changes are in balance.

 

Random genetic changes for evolution should imply that the first life should have circled around a stagnation point, because a crap shoot for genetic changes should go forward and backwards, with anything gained eventually balanced by it very loss. Life could never have left simple cells, since even if it gained that ability, random eventually comes around, and will do the opposite. For every heads there are equal amounts of tails, even if we get a string of heads. Then we should expect a string of tails with life back to where it was; stagnation.

[Skye]

Evolution works under the assumption that the aqueous and protein grids within cells (membranes and cytoplasm) can not tweak the DNA via cause and effect with the environment. Rather, it assumes changes in the DNA are detached from the rest of the cell and occur randomly. I tend to believe the DNA is tweaked by the rest of the cell. This allows life to keep its finger on the pulse of the environment and adapt as needed.

 

One line of reasoning that supports cause and effect, is if we assume random changes in the DNA, aren't there more things that can go wrong, than right, since random changes not only means improvements but also regressions. Random means the good genetic stuff, is also under random change into worse.

 

The parallel scenario that random creates is that selective advantage can be connected to avoiding bad random genetic changes. If the all the rest of the animals get more defects, due to random, and you get fewer, one has a selective advantage and therefore be called more evolved.

 

However, evolution is usually expressed in terms of something positive, which gives selective advantage. That can not be random, since advantage implies is a sense of direction, relative to what could happen if we randomly tweaked genes; good and bad changes are in balance.

 

Random genetic changes for evolution should imply that the first life should have circled around a stagnation point, because a crap shoot for genetic changes should go forward and backwards, with anything gained eventually balanced by it very loss. Life could never have left simple cells, since even if it gained that ability, random eventually comes around, and will do the opposite. For every heads there are equal amounts of tails, even if we get a string of heads. Then we should expect a string of tails with life back to where it was; stagnation.

 

Pioneer are you trolling, or are you unable to figure out how a theory of natural selection would lead to selective advantage?

[D H]

Evolution does not really drive towards more sophisticated or complex forms, except incidentally. The evolutionary pressure is entirely towards propagating one's genes in the most successful means possible in the present environment.

I agree with the first sentence. The last sentence, not so much. Evolution is a slow and inefficient process. The reason there is so much biological diversity on the Earth now is because evolution had a long, long time (3.8 billion years or so) to overcome the inherent slowness and inefficiency of the process.

 

Evolutionary pressure does not necessarily come from the environment. It can come from within. Sexual selection pressure can arise in what some view to be maladaptations. Deer and their oversized antlers, birds and their ostentatious plumage, humans and their bad boys/nasty girls.

 

Even when evolutionary pressure does come from the environment, it can be the wrong part of the environment ("wrong" in the sense of a gods-eye view of the best direction a species should be heading to ensure long-term survival). Evolution does not have a gods-eye view. It has no long-term view, no intelligence, a limited tool set. It creeps across the evolutionary landscape.

 

Evolution blindly and stupidly responding to immediate evolutionary pressure, and even then only to the pressure it is equipped to respond to. When it can respond, the response can be stupid. Species can go into all-out interspecies arms race with the end result being a Pyrrhic victory. The opposite extreme of an arms race is cooperation, and this too can be problematic. Avocados depend on ground sloths to disperse their fruit. One problem with that: ground sloths went extinct with the other megafauna.

 

It's not really possible for a species to "evolve" into extinction, by definition.

I definitely disagree with that statement. Overspecialization and sexual selection can seal the fate of a species. Genetic drift can push a species down a wrong path. You are giving evolution more credit than it is due. It is slow, inefficient, stupid, and blind. 99.9% of all species that have existed are extinct.

[JP]

Evolution works under the assumption that the aqueous and protein grids within cells (membranes and cytoplasm) can not tweak the DNA via cause and effect with the environment. Rather, it assumes changes in the DNA are detached from the rest of the cell and occur randomly. I tend to believe the DNA is tweaked by the rest of the cell. This allows life to keep its finger on the pulse of the environment and adapt as needed.

DNA is affected by parts of the cell (i.e. physical conformation), but to suggest that the genetic code directly mutates as a result of contact with external stimuli is just plain incorrect.

 

One line of reasoning that supports cause and effect, is if we assume random changes in the DNA, aren't there more things that can go wrong, than right, since random changes not only means improvements but also regressions. Random means the good genetic stuff, is also under random change into worse.

Positive/beneficial/bad/worse are all terms that are fairly poorly used when it comes to talking of evolution (i.e. Is any mutation that is passed on to successive generations beneficial??). Sickle cell anemia is "positive" in areas of say, Africa, where malaria is abundant and this mutation makes humans impervious to the disease. Anywhere else that cases of malaria are few and far between, this is obviously a negative issue - for us.

 

As far as the odds dictating more negative changes, why? Quite simply, most mutations are benign.

 

The rest of your argument really seems to slide down to the semantic argument of directionality and the usage of positive/negative mutations. I'm sure you can lookup any number of sources to verify that your claims are a little off-base.

[Sisyphus]

 

Evolutionary pressure does not necessarily come from the environment. It can come from within. Sexual selection pressure can arise in what some view to be maladaptations. Deer and their oversized antlers, birds and their ostentatious plumage, humans and their bad boys/nasty girls.

 

But those "maladaptions" are still necessarily beneficial in the immediate environment. The deer with bigger antlers DO have more offspring, because the environment includes other deer, who are more likely to accept deer with impractical antlers as mates. Would they be better off in the long term if other deer favored more practical antlers? Yes. So?

 

Certainly it shows "poor planning," but that's because it isn't planned. By definition, natural selection cannot favor anything but that which propagates genes more successfully. Things like sexual selection are the same, just focusing on that part of the environment consisting of other members of the same species.

 

Even when evolutionary pressure does come from the environment, it can be the wrong part of the environment ("wrong" in the sense of a gods-eye view of the best direction a species should be heading to ensure long-term survival). Evolution does not have a gods-eye view. It has no long-term view, no intelligence, a limited tool set. It creeps across the evolutionary landscape.

 

Evolution blindly and stupidly responding to immediate evolutionary pressure, and even then only to the pressure it is equipped to respond to. When it can respond, the response can be stupid. Species can go into all-out interspecies arms race with the end result being a Pyrrhic victory. The opposite extreme of an arms race is cooperation, and this too can be problematic. Avocados depend on ground sloths to disperse their fruit. One problem with that: ground sloths went extinct with the other megafauna.

 

I don't disagree with any of this. Blind, yes. Stupid, yes. But the response is still towards better gene propagation. The avocado wouldn't have become dependent on ground sloths unless that (or rather, the adaptations that led to that) lent an advantage at the time.

 

I definitely disagree with that statement. Overspecialization and sexual selection can seal the fate of a species. Genetic drift can push a species down a wrong path. You are giving evolution more credit than it is due. It is slow, inefficient, stupid, and blind. 99.9% of all species that have existed are extinct.

 

I am not giving evolution more credit than it's due, you're just reading more into what I've said than is there. That isn't "evolving to extinction," that's past evolutionary "choices" having detrimental effects in the present.

[michel123456]

It's not really possible for a species to "evolve" into extinction, by definition.

 

This statement triggers my mind. DH's intervention was a relief. Overspecialization is the case of Homo Sapiens. But still... I wonder. Is it inconceavable that under the pression of evolution, a specie goes into degeneration ?

[CharonY]

There is no degeneration in evolutionary terms. Homo sapiens tend to be very little specialized compared to those adapted to narrower ecological niches (not least due to the ability to carve out niches).

"Evolving into extinction" is an odd term as it again assumes a direction of sorts. Selection works on the current pool and shapes its composition (again, I caution to equate evolution with selective pressures or to limit it to the consequences thereof) but normally you cannot draw a trajectory out of that.

But in hindsight it is possible to identify adaptations that, while working at a given time point in the past may have a significant contribution towards their extinction at another time point. One has to remember that evolution is not a view in the future, but towards the past.

[michel123456]

I was thinking about a situation where some specie is getting attacked by the whole environnemental pressure and naturally tends to disappear.

Instead of "only the strong survive", imagine "all the strong die, only the weak survive". Like when a ship sinks, the women & children are saved, the captain dies.

Edited June 1, 2010 by michel123456

[CharonY]

What you describe sounds like normal extinction.

[Moontanman]

Evolution does not really drive towards more sophisticated or complex forms, except incidentally. The evolutionary pressure is entirely towards propagating one's genes in the most successful means possible in the present environment. Sometimes the efficiency of simplicity outweighs the advantages of complexity. Some of the simplest organisms are arguably the most "successful" of all.

 

It would appear there is some support for the idea that evolution drives toward complexity.

 

http://www.sciencedaily.com/releases/2008/03/080317171027.htm

 

First 'Rule' Of Evolution Suggests That Life Is Destined To Become More Complex

 

ScienceDaily (Mar. 18, 2008) — Researchers have found evidence which suggests that evolution drives animals to become increasingly more complex.

[Rip:20]

It would appear there is some support for the idea that evolution drives toward complexity.

 

http://www.sciencedaily.com/releases/2008/03/080317171027.htm

 

This is for animals only.

 

As the authors point out, bacteria are some of the most successful organisms on earth and yet remain single celled (mostly). By successful they mean most diverse in terms of "species", and probably largest total bio mass.

Edited June 2, 2010 by Rip:20

[michel123456]

What you describe sounds like normal extinction.

 

Yes, but I choosed a bad example. A ship wreck corresponds to an extinction caused by some external event. I was thinking more of a kind of process driving naturally a specie to extinction without any catastrophe. As if you considered a whole specie as an immense single organism, born, living, & dying.

[Rip:20]

I agree with the first sentence. The last sentence, not so much. Evolution is a slow and inefficient process. The reason there is so much biological diversity on the Earth now is because evolution had a long, long time (3.8 billion years or so) to overcome the inherent slowness and inefficiency of the process.

 

Evolutionary pressure does not necessarily come from the environment. It can come from within. Sexual selection pressure can arise in what some view to be maladaptations. Deer and their oversized antlers, birds and their ostentatious plumage, humans and their bad boys/nasty girls.

 

Even when evolutionary pressure does come from the environment, it can be the wrong part of the environment ("wrong" in the sense of a gods-eye view of the best direction a species should be heading to ensure long-term survival). Evolution does not have a gods-eye view. It has no long-term view, no intelligence, a limited tool set. It creeps across the evolutionary landscape.

 

Evolution blindly and stupidly responding to immediate evolutionary pressure, and even then only to the pressure it is equipped to respond to. When it can respond, the response can be stupid. Species can go into all-out interspecies arms race with the end result being a Pyrrhic victory. The opposite extreme of an arms race is cooperation, and this too can be problematic. Avocados depend on ground sloths to disperse their fruit. One problem with that: ground sloths went extinct with the other megafauna.

 

 

I definitely disagree with that statement. Overspecialization and sexual selection can seal the fate of a species. Genetic drift can push a species down a wrong path. You are giving evolution more credit than it is due. It is slow, inefficient, stupid, and blind. 99.9% of all species that have existed are extinct.

 

When you think about natural selection on each generation from the species point of view, it does seem there is no "long-term view". You need to think about the broader gene pool (outside of the arbitrary species delineation). Once you start thinking about survival of individual genes within larger clades then you can see how enormous diversity can be used to buffer against changes in the fitness landscape. One reason that there are so many forms of life is a result of how all (most) fitness landscapes always change though time. But old adaptations that are suboptimal in the current fitness selection arena are not just historical relics that are doomed for extinction, they can be reshaped or re-appropriated to be useful in future environments.

 

Your example of the avocado is pretty funny b/c although yes, the megafauna are gone , now humans have decided that the avo fruit is delicious and have extended the plant's range via cultivation. I have one growing in my office here in Colorado. Serendipitous evolution for the avo tree, no?

 

--Rip:45

Edited June 2, 2010 by Rip:20

[Rip:20]

When you think about natural selection on each generation from the species point of view, it does seem there is no "long-term view". You need to think about the broader gene pool (outside of the arbitrary species delineation). Once you start thinking about survival of individual genes within larger clades then you can see how enormous diversity can be used to buffer against changes in the fitness landscape. One reason that there are so many forms of life is a result of how all (most) fitness landscapes always change though time. But old adaptations that are suboptimal in the current fitness selection arena are not just historical relics that are doomed for extinction, they can be reshaped or re-appropriated to be useful in future environments.

 

Your example of the avocado is pretty funny b/c although yes, the megafauna are gone , now humans have decided that the avo fruit is delicious and have extended the plant's range via cultivation. I have one growing in my office here in Colorado. Serendipitous evolution for the avo tree, no?

 

--Rip:45

 

A further twist on the avocado is that it was probably humans who drove the seed's disperser, the giant ground sloth, to extinction through hunting.

[kitkat]

A further twist on the avocado is that it was probably humans who drove the seed's disperser, the giant ground sloth, to extinction through hunting.

 

 

Perhaps it is the plant life (fruits, flowering plants) that have a direct influence of how new species emerge in adaptations, diet that is specific to different species of plant life that ensures their survival.

[eleven]

Sea, Land, Air - In that order?

Sea + Air > Land - Or in this order?

[Ringer]

A ship wreck corresponds to an extinction caused by some external event. I was thinking more of a kind of process driving naturally a specie to extinction without any catastrophe. As if you considered a whole specie as an immense single organism, born, living, & dying.

Most of the time when a species becomes extinct it's without any "catastrophe". Say a foreign predator somehow makes it's way into an ecosystem that has no defenses against said predator, many prey animals may very well become extinct due to the predator coming into a niche that other species aren't designed for (design being used loosely). One example is somewhere in Washington there are worms used as fish bait that aren't usually naturally there. Now much of the plant life is dying because the worms give off a different waste substance, at least that's what I got out of the news report.

[Moontanman]

This is for animals only.

 

As the authors point out, bacteria are some of the most successful organisms on earth and yet remain single celled (mostly). By successful they mean most diverse in terms of "species", and probably largest total bio mass.

 

 

What do you mean animals only? Animals evolved form simpler organisms, why the perceived disconnect?

[Neco Vir]

michel123456 (I apologize if that is incorrect), my favorite analogy of what I think you're getting at is the rare white tiger, specifically that a recessive gene gives them their white fur instead of the normal orange colour. White tigers are rare because (as most of you know) they cannot blend in with their surroundings in their natural habitats, but they also have an advantage over normal tigers, the majority of white tigers are bigger in size than normal tigers both at birth and at adulthood. Certain white tigers also don't ever have stripes in their fur because of this gene which is a big setback in their predatorial behavior.

Sorry for getting off-topic kinda. So to get completely back on topic, tigers originally evolved/adapted/whatever you want to say, and this white fur gene was a result. But whatever use it had is now gone and now it would seem to most, that the course of evolution and survivalism is taking a turn for the worst for these poor tigers.

 

I hope this helps, is relevant to this topic, and all I have said is at least partially correct, please correct me if not, and if you want sources, sources will be given.

 

As far as degeneration, for now (I think) it is science fiction, even though it is possible.

 

 

[needimprovement]

I was a kind of bored and got reading some stuff in this evolution area.

 

I think evolution is misunderstood. (my opinion)

 

As a read threads here, it seems that the concept of evolution is that of a conjecture where all species (including plants) develop along a line from simple living beings into more sophisticated & adapted ones.

 

It is a part of the conjecture, but IMO it is not the whole story. At each moment of the living Earth history, the whole biosphere must have worked as an interlace of relations between species, a net in constant dynamic equilibrium.

 

If a specie is not adapted to its environnement, it is believed (as I read here around) that evolution is supposed to drive this specie into more adaptatation. But it can also drive this specie to extinction. Not because the specie was "bad formated', but because environemental conditions change.

 

You can be a wonderful specie and suddenly disappear because your place will be, bit by bit, set at the edge of the net. At some point, a little push will set you out. Some other specie can remain in the eco-system for million of years, never reaching the edge of the net, and never falling out.

 

 

So, IMO evolution is not always a procedure going from simple to complicated. Simple organisms can evoluted or can disapear, and so for complicated organisms.

 

As a resume, i believe that evolution don't work always for better. It can also drive to extinction.

We all live in an extremely complex conglomeration of niches. Species who were once at an advantage because of their physical attributes can suddenly find themselves facing odds that will lead to their extinction. These odds could be caused by environmental factors including other competing species and environmental stresses such as meteorites, droughts, earthquakes. Or it can take a long time, as you've described.

 

There are always stresses on a species. Evolution is not always a procedure going from simple to complicated. Look at the cockroach (if you can stand to). It's been essentially the same for an awfully long time and has been one of the most successful species time-wise. It has adapted so well that it can live just about everywhere. I doubt it will become more complicated simply because it is so successful in its current form.

[needimprovement]

As a resume, i believe that evolution don't work always for better. It can also drive to extinction.

Is it evolution that drives to extinction, or unfitness?

[Mr Skeptic]

Part of evolution is eliminating unfitness. Either within species or between species. Also sometimes species evolve to be completely dependent on a particular environment (see islands and predators for example), and then when the environment changes they might go extinct.