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Author Topic:   How do we know about natural selection? (Igor and Lithodid-Man only)
igor_the_hero
Inactive Member


Message 31 of 43 (302732)
04-09-2006 10:02 PM
Reply to: Message 30 by Lithodid-Man
04-07-2006 3:06 AM


Re: Waiting for mutation
Sorry for the delayed response. This has been a very hectic few days. Okay, now if mutations have to coincide with the environment then why aren't all the species going extinct? Humans are changing the whole Earth except for the most inhospitable geographical zones (mountains, deserts,etc.) We pollute the air so all creatures lungs would have to be mutating. (Although with oil becoming harder to find that is a bad example.) We are cutting down trees, making some animals have to find homes in stuff we make. They will have to mutate to eat our litter as we make their own food hardr to find. What I am asking is why aren't animals going extinct when we are changing the environment so rapidly?
This message is a reply to:
 Message 30 by Lithodid-Man, posted 04-07-2006 3:06 AM Lithodid-Man has responded

Replies to this message:
 Message 32 by Lithodid-Man, posted 04-14-2006 6:22 AM igor_the_hero has responded
 Message 33 by crashfrog, posted 04-14-2006 8:59 AM igor_the_hero has not yet responded

  
Lithodid-Man
Member (Idle past 314 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 32 of 43 (304156)
04-14-2006 6:22 AM
Reply to: Message 31 by igor_the_hero
04-09-2006 10:02 PM


Extinction
Sorry for the delayed response. This has been a very hectic few days.

I understand! I am also very busy and apologize for this delay.

What I am asking is why aren't animals going extinct when we are changing the environment so rapidly?

Your question is complex and I do not have all of the answers. First and foremost, extinction is occuring at a rapid rate. What is important to remember is that extinction in a human sense and extinction in a 'real world' sense may be different things. We call a species extinct when all known members of that species are no longer in existence anywhere. That would be a human definition. This occurs at a frightening rate as we alter critical habitat types.

But what is ultimately more destructive is local extinction. We kill off a population of organisms in a given region. A species might be in existence in region A and region C, but every individual in region B is gone. This limits A & C each to their own potential mutations (assuming that those individuals in region B were between the other two). Without that extinction an adaptation in A, B, or C could have spread to the other two. By eliminating B we didn't just take 1/3 of the variation out of the population we took 2/3 from both A and C. This is called fragmentation, and is a HUGE problem in conservation biology. Think about it, we rarely destroy all of a particular habitat, we like to set aside parcels of 'pretty' land. Those parcels may be too far apart for most species to cross.

As far as air pollution, I think in reality it is (at least at this time) fairly localized. Most areas of the planet don't have to deal with the smog of LA, Tokyo, etc. That pollution is having an effect everywhere, but the change is slow in most of the terrestrial biomes. I am very much an environmentalist, but also try to have the scientific background to look at multiple environmental issues. A single volcano can cause local extinctions for thousands of square kilometers around it and change climate for decades. The point is that species are adaptable. Life survived a comet that put the entire planet into an ice age (the end of the Cretaceous). Even more amazing (as an invertebrate zoologist) is the Permian event where over 90% (actually calculated at 96%!) of life on this planet was wiped out by an unknown factor (probably multiple factors).

Humans in the last few centuries are changing the planet at an alarming rate. Countless species are going extinct and some are adapting. Where this differs from historical events is that we can recognize and stop some of this from happening.

Honestly though, and I enjoy my soapbox, I need to keep this to the topic. I welcome any questions regarding our past topics or any new ones relating to evolution or natural selection. Thank you for the great question. - Aaron


This message is a reply to:
 Message 31 by igor_the_hero, posted 04-09-2006 10:02 PM igor_the_hero has responded

Replies to this message:
 Message 34 by igor_the_hero, posted 04-15-2006 2:29 PM Lithodid-Man has responded

    
crashfrog
Inactive Member


Message 33 of 43 (304171)
04-14-2006 8:59 AM
Reply to: Message 31 by igor_the_hero
04-09-2006 10:02 PM


Re: Waiting for mutation
Deleted

This message has been edited by crashfrog, 04-16-2006 01:01 AM


This message is a reply to:
 Message 31 by igor_the_hero, posted 04-09-2006 10:02 PM igor_the_hero has not yet responded

  
igor_the_hero
Inactive Member


Message 34 of 43 (304452)
04-15-2006 2:29 PM
Reply to: Message 32 by Lithodid-Man
04-14-2006 6:22 AM


Re: Extinction
Quote:Your question is complex and I do not have all of the answers.

Okay, this was taken a bit out of context. If we do not have all the answer why this mostly taught as a proven fact? I do not rememeber who it was but somebody on here said, "Evolution is proven except for the lack of proof that we just have to find." In science the last time I checked, when you have no proof the thing is unproven. Now, where is all the proof for natural selection. I remember the example you used about the deer and dandelions. What I mean really is where is the proof?


This message is a reply to:
 Message 32 by Lithodid-Man, posted 04-14-2006 6:22 AM Lithodid-Man has responded

Replies to this message:
 Message 35 by Lithodid-Man, posted 04-15-2006 7:24 PM igor_the_hero has responded

  
Lithodid-Man
Member (Idle past 314 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 35 of 43 (304493)
04-15-2006 7:24 PM
Reply to: Message 34 by igor_the_hero
04-15-2006 2:29 PM


Evolution is a fact
Igor,
This gets heavy into the nuts and bolts of science. When dealing with evolution it is important to separate fact from theory. The FACT of evolution is that organisms change, new species arise, etc. This is observable and supported by a large number of independant observations from different scientific disciplines (genetics, morphology, paleontology, etc). The THEORY of evolution is an attempt to explain the mechanism by which evolution occured. Facts are what we can observe or infer, theories are attempts to explain mechanisms.

A suitable analogy comes from the dandelion example:
FACT: Dandelions in the mowed lawn are short.
THEORY: Dandelions are short because mowing selected those with short genes.

Another example of this is gravity. You have heard of the Theory of gravity, I assume. So, why is gravity a theory when you can drop a brick and watch it fall? Shouldn't it be a proven fact? In this case the brick falling is a FACT. It is proven that bricks fall everytime. The theory is why that happens or by what rules it happens. Isaac Newton derived an equation that describes the attraction of masses. So far his equation has not been refuted, everywhere we look we see the same relationship. As to what causes gravity there are a number of theories (I am not familiar enough with these to even begin to discuss them!) but as I understand it gravity is still something of a mystery.

With evolution the FACT is change in organisms, the THEORY is the mechanism of natural selection. It is possible (although highly unlikely) that we will one day discover a new mechanism that explains the observed changes better than natural selection. It is recognized today that a mechanism called genetic drift can cause changes without natural selection (although these changes are mostly restricted to the non-expressed gene level). Natural selection is strongly supported because it has resisted falsification for nearly 150 years.

The word 'theory' is commonly misused on this topic. Nearly every single creationist source makes the claim "Evolution is only a theory." This is using the word not in a scientific sense but in a popular jargon context. If I wake up and find my shoes chewed I might say, "I have a theory about how this happened." I do not mean that I am going to design experiments, test different hypotheses, etc. I mean, "I have an idea about what caused this". When we say "The Theory of Evolution" we don't mean "We have an idea about how this happened". The ToE refers to a set of hypothese and predictions that have been tested and could not be disproven. Just like the Theory of Gravity, Atomic Theory, etc.


Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"
This message is a reply to:
 Message 34 by igor_the_hero, posted 04-15-2006 2:29 PM igor_the_hero has responded

Replies to this message:
 Message 36 by igor_the_hero, posted 04-18-2006 8:34 PM Lithodid-Man has responded

    
igor_the_hero
Inactive Member


Message 36 of 43 (305057)
04-18-2006 8:34 PM
Reply to: Message 35 by Lithodid-Man
04-15-2006 7:24 PM


Re: Evolution is a fact
But when you consider theories, what about laws? The Laws of Thermodynamics for example. Those aren't theories, they have been successfully proven.
This message is a reply to:
 Message 35 by Lithodid-Man, posted 04-15-2006 7:24 PM Lithodid-Man has responded

Replies to this message:
 Message 37 by NosyNed, posted 04-18-2006 8:55 PM igor_the_hero has not yet responded
 Message 38 by Lithodid-Man, posted 04-21-2006 4:23 AM igor_the_hero has responded

  
NosyNed
Member
Posts: 8752
From: Canada
Joined: 04-04-2003
Member Rating: 10.0


Message 37 of 43 (305065)
04-18-2006 8:55 PM
Reply to: Message 36 by igor_the_hero
04-18-2006 8:34 PM


Laws and Theories

Igor, the actual terms used are more a matter of history than anything else. "Law" isn't a term used much any more other than for historical ideas.

However, if you look them over you might see that "laws" are usually simpler - probably single equations or statements like Newton's "Laws" of motion. Theories, on the other hand, are much more powerful constructs and can be expected to have "laws" as an outcome. Thus, Newton's "law" of gravitation is a consequence of the Theory of Gravity put forward by Einstein.

Theories and laws aren't "proven" in the mathematical sense; they are "proven" in the sense that they seem to work really, really well in lots and lots of circumstances.

The "laws" of thermodynamics are in that class and so is Einstein's general theory of relativity and the theory of evolution. They are all approximately equally solid and "proven" to all practical purposes.

This is a Great Debate between Igor and Lithodid-Man. Please let them continue. Content hidden.

This message has been edited by AdminJar, 04-18-2006 08:20 PM


This message is a reply to:
 Message 36 by igor_the_hero, posted 04-18-2006 8:34 PM igor_the_hero has not yet responded

  
Lithodid-Man
Member (Idle past 314 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 38 of 43 (305600)
04-21-2006 4:23 AM
Reply to: Message 36 by igor_the_hero
04-18-2006 8:34 PM


Re: Evolution is a fact
But when you consider theories, what about laws? The Laws of Thermodynamics for example. Those aren't theories, they have been successfully proven.

The term 'Law' in science is actually pretty vague. In a mathematical sense a law might be akin to a proof. Because there are no proofs in science, laws really do not have any meaning. I am not saying that there are no scientific laws, just that they are not readily defined.

For the most part, scientific laws are restricted to absolute relationships that can be defined in simple mathematical terms. Laws of physics, laws of chemistry. The former includes the laws of thermodynamics. These are theories that have been tested so extensively and for so long that we are extremely certain that the equation will predict all future experiments. But they are still not proven.

But what is important to keep in mind is that the concept of a law in science is not something that a panel decides. A law is no different from a theory in a real scientific sense. Most areas of science cannot be defined by a simple equation. This is why most laws are restricted to physics.

You will hear mention of biological laws, such as 'The Law of Abiogenesis'. This has no real meaning. This was dubbed in a different time and in a different context and has no meaning now.

I hope this makes sense - LM


Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"
This message is a reply to:
 Message 36 by igor_the_hero, posted 04-18-2006 8:34 PM igor_the_hero has responded

Replies to this message:
 Message 39 by igor_the_hero, posted 04-28-2006 3:57 PM Lithodid-Man has responded

    
igor_the_hero
Inactive Member


Message 39 of 43 (307462)
04-28-2006 3:57 PM
Reply to: Message 38 by Lithodid-Man
04-21-2006 4:23 AM


Mistakes and Glories
When natural selection is in action, how do we get the correct mutation? For example, I have been told that oxygen is actually a poisonous gas. Well, since oxygen is required now to breathe then how could we have evolved that way. We couldn't have inhaled it gradually or else we would have died. What I am asking, how did the whole thing turn out like this where we are all alive? Mutations are supposed to take a while so I don't see how it could have just happened.
This message is a reply to:
 Message 38 by Lithodid-Man, posted 04-21-2006 4:23 AM Lithodid-Man has responded

Replies to this message:
 Message 40 by Lithodid-Man, posted 05-01-2006 7:47 PM igor_the_hero has responded

  
Lithodid-Man
Member (Idle past 314 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 40 of 43 (308314)
05-01-2006 7:47 PM
Reply to: Message 39 by igor_the_hero
04-28-2006 3:57 PM


Oxygen
Hi Igor,

You are correct, oxygen was very bad for early lifeforms (and many still living). The earliest abundant organisms were a type(s) of bacteria called cyanobacteria or blue-green algae. It is believed that these changed the world, literally.

At this time there was very little free oxygen in Earth's atmosphere. The oxygen was bound in water molecules and carbon dioxide. The first photosynthetic (actually probably chemosynthetic) organisms were capable of fusing carbon dioxide and water to make simple sugars. The by-product of this is oxygen (same as now). At first this would be no problem as the atmosphere is very big. However, it is thought that after billions of years the atmosphere began to accumulate enough free oxygen that whole groups became extinct. Those that survived (remember, these are bacteria) were those who could tolerate the own waste products the best. Out of those who could tolerate it came those who could actually use this oxygen as an energy source in their cellular processes. Because oxygen is so energetic (gives off a great amount of enery when combined with other atoms) these organisms could do things no prior cells could do. New forms of movement, forming symbiotic relationships, become multicellular, etc.

What is very interesting is how long this took. The earliest life is about 3.8 billion years old. For all but the last 1.7 billion years (less than half) these bacteria were all that there was for life on Earth. For over 4/5 of the history of life there was nothing we would recognize as a plant or an animal by today's standards. Because of this it is thought that life probably arose quickly (as soon as the Earth cooled enough to allow liquid water). But after the first lifeforms arose very little overall change occured for a long time.


Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"
This message is a reply to:
 Message 39 by igor_the_hero, posted 04-28-2006 3:57 PM igor_the_hero has responded

Replies to this message:
 Message 41 by igor_the_hero, posted 05-01-2006 8:24 PM Lithodid-Man has responded

    
igor_the_hero
Inactive Member


Message 41 of 43 (308318)
05-01-2006 8:24 PM
Reply to: Message 40 by Lithodid-Man
05-01-2006 7:47 PM


Re: Oxygen
Then did we just kind of stop? When the air gets polluted like it is now, are we just sort of adapting to it?
This message is a reply to:
 Message 40 by Lithodid-Man, posted 05-01-2006 7:47 PM Lithodid-Man has responded

Replies to this message:
 Message 42 by Lithodid-Man, posted 05-08-2006 3:05 AM igor_the_hero has not yet responded

  
Lithodid-Man
Member (Idle past 314 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 42 of 43 (310194)
05-08-2006 3:05 AM
Reply to: Message 41 by igor_the_hero
05-01-2006 8:24 PM


Did we stop
Hi Igor,

I am not sure exactly what you are asking. Do you mean have we stopped evolving? To that the answer is no. Every reproducing population is evolving. Even if there is no visible changes, frequencies of genes are changing generation to generation.

About adapting to air pollution in modern times. I think some things are certainly adapting to it. As for us, probably not very much. While the air is polluted in localized areas, nowhere is it so bad that it significantly changes our reproductive rate. It is not outside the realm of possibility that in really bad areas, like Mexico City there could be an increase in smog to the point that it could cause a reduction in survivorship. One possibility could be that those with hemoglobin better able to bind oxygen over carbon monoxide (I assume this is physiologically possible) or better able to unbind carbon monoxide would have more children and we would see people in those regions better able to tolerate pollution.


Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"
This message is a reply to:
 Message 41 by igor_the_hero, posted 05-01-2006 8:24 PM igor_the_hero has not yet responded

    
westernjoe
Junior Member (Idle past 2940 days)
Posts: 9
Joined: 01-09-2007


Message 43 of 43 (375746)
01-09-2007 5:04 PM
Reply to: Message 14 by Lithodid-Man
03-27-2006 2:50 AM


Re: Great question!
Sincerely regret, westernjoe, but this is a private, one-on-one debate between LithidodMan and Igor. No other poster is permittted to comment in this thread.

If you would like to comment, please open a new, general membership thread using the standard PNT format.

Content deleted.

Edited by westernjoe, : No reason given.

Edited by westernjoe, : No reason given.

Edited by AdminQuetzal, : No reason given.


This message is a reply to:
 Message 14 by Lithodid-Man, posted 03-27-2006 2:50 AM Lithodid-Man has not yet responded

    
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