Evolution?

Bombila said:

How can you be bored with minute lifeforms when there are things like cordyceps out there? It ain't pretty, what it does, but it certainly isn't boring.

http://ca.youtube.com/watch?v=xa0uxeHDgBg&feature=related

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Zombie fungus. Nothing but fun.

juvenissun said:

This is an example of argument that I don't like the most about evolution from any point of view. When convenient, evolutionist said that something "wins" in evolution struggle. When necessary, they said there is no such thing called "success".

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Where did anyone say that there was no such thing as "success"?

Let me try to explain what "winning" means in evolution. There is a concept called "competitive exclusion" in ecology. It's probably what's happened to poor red squirrels of Britain. Grey squirrels were brought in from North America, and in relatively short time the red squirrels practically disappeared from many grey-infested areas. This is likely a clear case of one species "winning" a struggle - greys very probably drove several red squirrel populations to extinction.

You can't say the same for our arms race with parasitic bacteria. We are still here, so we can obviously keep them at bay. But they keep infecting us, so we don't "win" either.

"Winning" in evolution means replacing a competitor or killing off a prey species (of course, the latter case only counts as "winning" if you survive their extinction ).

Success is very hard to measure. You could choose all sorts of metrics and I don't think there is a clear best choice.

Number of individuals? Well, you can obviously stuff more small things into a given habitat than big things. Not really a good metric.

Amount of biomass? But biomass tends to decrease as we go up the food chain. Does that make lions less successful than grass?

Size? Mammals grow bigger than most other animals and sit on the top of many food chains. Does that make them more successful than, say, insects, who are by far the most diverse type of animal on earth but rarely end up as top predators?

You could do similar exercises with species diversity, diversity at higher taxonomic levels and probably quite a number of other possible metrics of success. To me it's not at all obvious which one is the best to use, and it also changes with the situation (you can't, say, use geographic range as an indicator for things confined to a small continent isolated from the rest of the world for many million years)

You want biology to be simple and straightforward. Some ideas are, but the sheer complexity of the living world prevents most real situations from being so.

When a goal is needed (to release environmental stress), they said things evolved toward the goal. When the goal could not be identified, they said evolution is not about reaching any goal.

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Again, when did we say that things evolved toward a goal? Evolution may show long-term trends that look goal-oriented (the fish-tetrapod transitional series is a great example, the "goal" being getting on land). These trends arise when there is a long-term pressure for some things to get better at doing X.

I see at least some of these trends as self-reinforcing: once an organism "invents" a rudimentary way of doing X, every step that improves the X ability will be advantageous, and every change that sends a descendant back to a previous state will probably be for the worse (because creatures better at doing X, and creatures good at doing what the X-ers' ancestors did before they started doing X, are still around).*

That doesn't mean there is a "goal". It's just repeated positive feedback from immediate fitness effects.

When attacked from one way, evolution ALWAYS has many ways to escape. But put all cases together, many principles of evolution contradict to one another.

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Such as? "Individual cases are radically different" =/= "Principles contradict". Only that not all principles are applicable to all scenarios.

Even in that situation, there is still an escape: the processes work to give the most benefit to a life form "at different places (niches) in different time". We have seen all these options in this long thread. The methodology of argument is simply opportunistic and non-sensical.

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Do you would think that all different conditions should produce exactly the same effect or what?

Yes, you can make up evolutionary just-so stories. There is a key point about them, though: they are, at least in principle, testable. There are ways to decide if an idea is right, or at least plausible.

For example, one advantage of becoming multicellular may be that you are bigger and harder to eat. You may arrive at this idea contemplating amoebae in the bath tub or in any other random way. But then you can go to a lab and test it. This particular idea turns out to be a viable possibility: unicellular algae put in the same culture as a unicellular predator evolved into a colonial form in very few generations.**

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*This idea came to me as I wrote this post, so it's fresh and not quite thought through. Feel free to point out problems

**Can get you a paper if you want me to. The original discovery was an accident IIRC, but replicated by proper experiment.

juvenissun said:

You do not know symmetry geometry.

Most animals have symmetry in "m" class, which has one reflective plane and is just slightly better than non-symmetrical. But bacteria seems have at least one dimension which is circular (the most symmetrical form), with at least one two-fold symmetrical axis.

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And you do not know developmental biology In multicellular things, it's more complicated to build a bilateral body than a more symmetrical one. Dunno how much that applies to single cells (they definitely don't have to coordinate the correct differentiation of huge numbers of cells), but I thought I'd just point it out.

juvenissun said:

This repeats the argument I made before: Bacteria is the most successful life form on earth.

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And will keep repeating until you get the message

All plants and animals are simply evolutional mistakes. (Yeah, I know, evolution makes no mistakes, it just adapts. I certainly heard this argument before).

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Well, actually all adaptations start out as mistakes, just lucky ones

juvenissun said:

So, if bacteria are good in surviving, then why would eukaryote cells do anything different? Obviously there is a more beneficial direction (goal) for them to go for (what is that?). If so, why won't bacteria do the same, and "lag behind" sooo long?

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Because, as I already said, even in the part of my post that you neglected to quote (and read?), there are different ways survive. We have examples of this in nature. I gave you such examples.

Basically, this is part of the content in the OP. I am just going nowhere on this question.

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Because you ignore the answers.

juvenissun said:

So, if bacteria are good in surviving, then why would eukaryote cells do anything different?

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They don't. They do exactly the same (which is to say, survive)

Obviously there is a more beneficial direction (goal) for them to go for (what is that?).

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No there isn't, and no it's not.

Basically, this is part of the content in the OP. I am just going nowhere on this question.

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It's been answered several times, you just do not understand the answer. Evolution is a process, not an entity. It doesn't have goals or purposes, any more than combustion has the goal of burning things.

juvenissun said:

I understand the concept of evolution is based on observation.

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Yet you consistently ignore the fact that there are multiple ways to survival.

It turns out there comes too many observations and the interpretations of them become contradict to each other.

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I have yet to see you give an example.

Then the contradicting interpretations are separated by geography and time to avoid the conflict.

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Different circumstances lead to different results. This is not a contradiction, it's basic logic.

All together, the concept of evolution becomes a non-logical, non-sensical monster, which is basically unfalsifiable. Here is an example:

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Oh goody.

There is always A reason to support the evolution of a particular life system, which has, say, 10 controlling factors. Even the reason A is contracting to reason B used in other case to support the evolution of the same system, it does not matter. Because reason A addresses factor a, b, c in the system and reason B address factors e, f, g of the same system. So if reason A is defeated, evolution still has reason B, reason C, etc. to support the same monstrous concept.

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I thought you'd given an example. Than do it. This is just blather.

edited to add: Basically what you are doing here, is complaining that when multiple factors are involved, we need to account for all of them. I thought you were a scientist (well, no, I thought you were lying about your claim to be a scientists, thanks for confirming that once again). The whole point of looking how something works in nature, is to account for all of it. Not just to pick some parts you like and ignore the rest, like you want to do. This does not mean that theories cannot be tested. It only means that you have to unravel the contributions of different circumstances.

juvenissun said:

"Bilateral" could fit into any one of classes 2, m, and 2/m. (monoclinic system)

Shapes of bacteria are MORE than bilateral.

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Did you pick a random page with the word "biology" in it? All you do is redefine words to fit your arguments (ex. mountains, evolution, symmetry).

juvenissun said:

I don't think you really mean what you said. When you turn around, you would say: Hey, that is where the evolution goes.

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No, evolution is a non-teleological process. It just happens due to mutations, natural selection, and genetic drift. Find an example where a biologist has said that evolution has a goal. And the person you quote has to be a biologist, preferably an evolutionary biologist, but a geneticist, microbiologist, molecular biologist, physiologist, etc work too.

But wait, that would require you to back up your posts with evidence. You never do that. And even when you provide a link it's completely irrelevant to the discussion. So far in this thread you have been given examples of bacteria evolution (including speciation), multicellular bacteria, and bacteria with different morphology. All you do is deny and dance around the point.

And for no good reason at all (because you'll just say it's not evolution or something equally stupid):
An example of bacteria evolution

juvenissun said:

I don't think you really mean what you said. When you turn around, you would say: Hey, that is where the evolution goes.

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Bad enough when you lying creationist weasels tell me what I think, now you have the galling hubris to tell me what I say?

Even your biblegod was never this arrogant.

juvenissun said:

I don't think you really mean what you said. When you turn around, you would say: Hey, that is where the evolution goes.

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The fact that you can predict where a process is going doesn't mean that process has a goal. What's the goal of a falling raindrop? Sodium chloride dissolving in water? Burning gas heating a pot of soup?

Juvenissun, I am a layperson, but maybe my simple understanding of evolution might help, because you seem to talk at cross-purposes.

If I have something glaringly wrong, I know someone with more expertise will correct me, so bear that in mind.

The problem, juvenissun, and the reason people keep saying you are failing to listen, is that you still say things that indicate you are holding onto wrong ideas about evolution. Evolution is a very simple concept made complex by all the factors that influence it. Lifeforms change over time, generation to generation, in response to habitat, climate, availability of food, ability to eat that food, predators, competition, disease, ordinary luck, and a myriad of other influences. Changes in alleles, mutations, allow this to happen. Those lifeforms which don't change fast enough when faced with changes in the things they need to survive to reproduce become extinct. Sometimes a lifeform is successful enough in its niche that it changes very slowly, since most of its members reproduce and the effect of any mutation is diluted by the population that doesn't have that mutation. Sometimes environmental pressure is such that a population is not surviving to reproduce, except for those few who have an adaptive mutation, then change comes faster, because the mutation is not diluted.

All that is necessary for the above to be true is time (sometimes a long time, sometimes a short time) and change. We know there has been plenty of time, so much that most of us can't even conceive of that much time. We know everything changes, that is a simple observation.

We have directly observed organisms from single celled bacteria and yeast to insects and lizards change in response to their environments, sometimes very fast, because those that don't change when the environment change is drastic don't live to reproduce.

You've likely seen this story before: http://news.nationalgeographic.com/news/2008/04/080421-lizard-evolution_2.html

but perhaps you haven't understood it. These lizards evolved rapidly, in only thirty generations, to live on vegetation. The lizards that did not have the capacity to eat some vegetation did not reproduce; they died. The ones that did, lived and laid eggs. Fast evolution in this case was influenced likely by plasticity - existing digestive structures that didn't require being entirely replaced (and I am simplifying hugely) by a whole new system, and possibly, the ability of many reptiles to consume some plant matter. (See this article about fruit eating alligators: http://scienceblogs.com/tetrapodzoology/2008/10/alligators_eat_fruit.php)

You say: "So, if bacteria are good in surviving, then why would eukaryote cells do anything different? Obviously there is a more beneficial direction (goal) for them to go for (what is that?). If so, why won't bacteria do the same, and "lag behind" sooo long? "

There is no goal except to reproduce successfully. Lifeforms don't 'go for a more beneficial direction', they just either reproduce or don't. You are aware that some populations of lifeforms are very few, in fact any mammal has a small population compared to insects or bacteria. But there are enough of most mammal populations that they reproduce enough to replace themselves, so they don't become extinct. You've repeatedly been told that bacteria have evolved and do evolve. And if a particular bacteria is never in an environment where it is more likely to survive as a multicelled colony, there is no pressure for it to become multi-celled, so any mutation that would support colonial living is diluted by the success of the whole population - there is no goal to 'become' something else.

It is possible that eukaryote cells in the distant past were in an environment that made survival as a colony more likely than survival as a single cell. Perhaps there were predators, and just being bigger was more successful. Perhaps it was colder, and being in a cilia-waving mass was advantageous to heat retention. Perhaps just the fact of having other cells close by made reproduction more efficient in the prevailing environment. There was no goal, no 'beneficial direction', just whatever worked to ensure successful reproduction for that particular lifeform in that particular environment/habitat.

That is what you seem fixated on, and why people think you don't understand. It isn't 'better' to evolve to be a species of a bacteria, or an insect, or a mammal, or a tree. It just happened, and happens, in response to the prevailing environment, which changes.

juvenissun said:

So, if bacteria are good in surviving, then why would eukaryote cells do anything different? Obviously there is a more beneficial direction (goal) for them to go for (what is that?). If so, why won't bacteria do the same, and "lag behind" sooo long?

Basically, this is part of the content in the OP. I am just going nowhere on this question.

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Because prokaryotes and eukaryotes occupy different ecological niches.

One other point that no one has brought up is that the evolution of eukaryotes required endosymbiosis (the evolution of prokaryotic symbiots into organelles, ie mitochondria and plastids). There have been examples of possible endosymbyoisis in progress discovered today, but it may be that since eukaryotes evolved and diversified, that it is now very hard to outcompete them in the niches they occupy. A new eukaryote-like ( or "endosymbiont") species may not be able to do as well as the better adapted eukaryotes that fill ecological niches today. Unless all eukaryotes become extinct (an unlikely scenario) there may be no way for a new endosymbiont to replace them.

Split Rock said:

Because prokaryotes and eukaryotes occupy different ecological niches.

One other point that no one has brought up is that the evolution of eukaryotes required endosymbiosis (the evolution of prokaryotic symbiots into organelles, ie mitochondria and plastids). There have been examples of possible endosymbyoisis in progress discovered today, but it may be that since eukaryotes evolved and diversified, that it is now very hard to outcompete them in the niches they occupy. A new eukaryote-like ( or "endosymbiont") species may not be able to do as well as the better adapted eukaryotes that fill ecological niches today. Unless all eukaryotes become extinct (an unlikely scenario) there may be no way for a new endosymbiont to replace them.

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Nathan45 and I sort-of made (or, in my case, contemplated) a similar point a few pages back:

Naraoia said:

[...]

I don't think size or multicellularity is the answer. IMHO the key step that prokaryotes are unlikely to make again is the leap to eukaryotic cells. Wouldn't a newly emerging proto-eukaryote necessarily be far less efficient than a modern eukaryote with all its sophisticated feeding mechanisms, transport equipment, mitochondria etc.? In this scenario, competition and not predation would be the main barrier to progress.

(That's just my idea based on patchy knowledge and gut feeling, so feel free to say no )

EDIT: Sorry, Nathan, didn't read your next post. It seems we are basically saying the same thing.

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Naraoia said:

Nathan45 and I sort-of made (or, in my case, contemplated) a similar point a few pages back:

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Sorry... I missed that. Good point by the way!! It desearved to be repeated, since juvenissun must have missed it too.

Split Rock said:

Sorry... I missed that.

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No problem, it was loooong ago. I wasn't even sure it was in this thread.

Good point by the way!!

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This strokes my wannabe scientist ego

It desearved to be repeated, since juvenissun must have missed it too.

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I think Juvenissun has problems with the English language or something. He seems to miss an awful lot of points.