The Gaia Theory

I discovered this theory on the wonderous WOW, or world of wikipedia. It is fairly understandable, but I want to know what you think!

http://en.wikipedia.org/wiki/Gaia_Theory

The zerg will overtake you! 


No, but really, I think it's ridiculous.

~D-Draw

thats friggen hilarious

I studied gaia theory in an environmental philosophy course a long time ago.

Trying to think of what Dr. Ponce had to say >.<

Anyway the weak gaia theory is reasonable, the biota do influence the abiotic, I wouldn't go so far as the strong gaia and say the earth is alive lol.  The weak gaia is likely true, organisms can manipulate the abiotic environment to make it more suitable for them, but it is not directed by the organisms in any sentient way.  The main examples of this is the production of an oxygenic atmosphere by cyanobacteria 3-2 billion years ago and control of global temperatures by oxygenic photosynthetic organisms.  A smaller example is the way acidothiobacillus bacteria produce sulfuric acid and pretty much dominate surface water contaminated with reduced iron (this is called acid mine drainage since it pretty much only occurs when reduced metals are dug up from underground and dumped near water).

 

Althought I'd never go as far as to say the Earth was an organism I would definitely agree with the idea that every life-form is interdependant in one way or another.

Please explain D-Draw

I just had the opportunity to see Lynn Margulis, probably the most prominent advocate of the Gaia hypothesis, speak at my college. The Gaia hypothesis makes sense in a limited fashion; life obviously does regulate certain aspects of the environment. She is absolutely correct that, for instance, the constant presence of large amounts of highly reactive compounds in our atmosphere (such as O2) is only maintained by biotic processes. However, I fail to see how that is a hypothesis, or anything new; I don't think any biologist disputes that biology plays a significant role in regulating the Earth's environment. Margulis also made a number of rather inane points. She said something along the lines of, "the only reason the environment is so comfortable for life is because life regulates it." Well yeah, life helps maintain it, but the main reason Earth is so comfortable for us is because we evolved to find it comfortable. A species that is too uncomfortable in its environment won't survive.
I also disagreed with a lot of her ideas about symbiogenesis. Yes, we see lots of symbiosis on the ecological level. Species evolve to cooperate. And certainly symbiogenesis has played a role; it is well established that our mitochondria are descended from bacteria. They have their own DNA. But there is no proposed mechanism for symbiogenesis on the macroscopic level. Two organisms can certainly grow very close symbiotically, but how does the 'parasite' genetic code get added to the host's DNA? In cases like mitochondria, where we have a complex unit inside a cell with its own DNA separate from the host cell's genetic material, we can reasonably conclude symbiogenesis. But since there is no proposed explanation for how the DNA of two symbiotic organisms can be merged, and indeed there is no evidence for it ever having occurred, we cannot conclude symbiogenesis for the origin of the great majority of novel systems over the course of evolution.

Please explain D-Draw

Well, see the Zerg have these Ultralisks, and they're these big monster things with claws, and...oh...right, the other thing...(the reference was due to the Zergs having an Overmind which connects the entire swarm so they all think and move as one organism)


I mean, it's rather obvious that things need each other to function. We need trees to produce oxygen and the trees need fertilizing, and we need protein which can come from meat, and the meat needs plants, and etcetera ad nauseam. That's all pretty simple to figure out--it's been repeated even in the most aged cultures such as Native Americans and African tribes. But to say that we are an "organism" just doesn't really make any sense. An organism is required to fit into specific criteria. We don't have an "overmind" per se, and we don't all act in synchronization, and often we work in exact opposition of each other fighting wars and what not. I know explicitly that I am not commanded to do what I do based on a nucleus hidden somewhere and thus I don't see how we could possibly be considered an "organism."

I'll admit that I do need to do some more reading up on this theory, so if I sound ignorant that's probably because I am. I'll research a bit more and see what I can figure out.

~D-Draw

I know how the zerg work... I used to play Starcraft until my dog ate the disk and died.

But thanks for explaining why you don't think the theory is good.

Margulis also made a disappointingly infantile point dismissing Richard Dawkins' 'selfish gene' hypothesis. "Genes don't have selves, so how can they be selfish?" A grown woman shouldn't be making such moronic statements, much less a respected scientist.

Also, D-Draw, Our body is made up of all kinds of cells that work together to provide a good living area for themselves. Does that mean we aren't one organism.

Margulis also made a disappointingly infantile point dismissing Richard Dawkins' 'selfish gene' hypothesis. "Genes don't have selves, so how can they be selfish?" A grown woman shouldn't be making such moronic statements, much less a respected scientist.

Even though she was making a dumb rhetorical question, it is true that the phrase "selfish gene" doesn't accurately describe genetic behavior. There isn't really a good single word to describe the behavior, so Dawkins chose "selfish" as the closest match. In reality, the gene is selfish in the sense that it possess a quality/qualities that give it an advantage in the Darwinian selection process - thus propagating or promoting itself.

I think you could call it "the self-promoting gene" and still be about on the mark with Dawkins' theory.

Quote from: dysfunction on April 24, 2007, 08:36:54 PM

Margulis also made a disappointingly infantile point dismissing Richard Dawkins' 'selfish gene' hypothesis. "Genes don't have selves, so how can they be selfish?" A grown woman shouldn't be making such moronic statements, much less a respected scientist.

Even though she was making a dumb rhetorical question, it is true that the phrase "selfish gene" doesn't accurately describe genetic behavior. There isn't really a good single word to describe the behavior, so Dawkins chose "selfish" as the closest match. In reality, the gene is selfish in the sense that it possess a quality/qualities that give it an advantage in the Darwinian selection process - thus propagating or promoting itself.

I think you could call it "the self-promoting gene" and still be about on the mark with Dawkins' theory.

Sure. But anyone of reasonable intelligence who had actually read Dawkins should have been able to see what he was getting at. The name of the concept may be very slightly misleading, but Dawkins exposits the concept very thoroughly in the text.
Stephen Jay Gould at least made a reasonable attempt at refuting the selfish gene idea, but failed. However, Dawkins was wrong in dismissing Gould's punctuated equilibria idea. It seems both were right about their own pet theories, but wrong about the other's.

Also, D-Draw, Our body is made up of all kinds of cells that work together to provide a good living area for themselves. Does that mean we aren't one organism.

They work together, they do not harbor guns and begin shooting each other, nor do they build massive on the surface of our skin.

~D-Draw

Two organisms can certainly grow very close symbiotically, but how does the 'parasite' genetic code get added to the host's DNA? In cases like mitochondria, where we have a complex unit inside a cell with its own DNA separate from the host cell's genetic material, we can reasonably conclude symbiogenesis. But since there is no proposed explanation for how the DNA of two symbiotic organisms can be merged, and indeed there is no evidence for it ever having occurred, we cannot conclude symbiogenesis for the origin of the great majority of novel systems over the course of evolution.

Maybe it is something like the T plasmid in agrobacterium tumeferens (hope I spelled that right) which manipulates its plant host's DNA. 
Perhaps the DNA isn't merged, but is just loss; most parasitic bacteria like vibrio sp. have very small genomes since they take so much from their host.