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Is Evolution Still Just A "theory"?

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(Split from a discussion about a specific court-decision on teaching of ID/evolution - sNerd)

Liriodendron, any thoughts on the use of the term "theory"?

I have often wondered about this - why are there no "laws" in biology? Why don't we refer to a "law of evolution" as we refer to a "law of gravity"?

I don't know the answer to this, other than to point out another example: no one would question Einstein's *theory* of relativity as a *fact*, either. (Or would they? Any physicists on the forum who could correct me?) I'm preaching to the choir here, but theory is not mere speculation. Even an educated guess that needs proving is a hypothesis.

Also, in biology, we have what is called the cell theory, which states that all cells come from other cells, and that all organisms are composed of cells, and that cells are the fundamental unit of life. I have no idea why it is still called a *theory*, since it is obvious that no one will ever be able to disprove this *fact*.

Perhaps the answer lies in that laws as defined in physics are universal in space and time and non-accidental.

Anyway, finally we have a judge making some sense!

Edited by softwareNerd
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I have often wondered about this - why are there no "laws" in biology? Why don't we refer to a "law of evolution" as we refer to a "law of gravity"?
I think because biology is not of the form P1V1 = P2V2,V1 / T1 = V2 / T2, PV=NRT or

    Helmholtz7.GIF

The implication is that these equations give you the whole answer. You can compute reality from these simple rules. As biology becomes more experimental and less observational, legal concepts could emerge more strongly (unless science goes off the deep end and rejects causation and predictability). But bad luck, there really aren't any quantitative laws of (specific to) biology, instead you can study specific facts about how G, T, A and C can combine to ultimate cause blond hair or venom, which will be an application of more basic physical laws. So I think the lack of hard-core laws in biology is bad timing on the part of biology.

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So I think the lack of hard-core laws in biology is bad timing on the part of biology.

I agree with what you said, but what do mean about "bad timing?" That we're just "not there yet" in predicting what happens in biological systems because there are too many factors to consider, but that we might be someday? I would be interested to hear what you think about this.

Anyway, why aren't Einstein's equations re: relativity considered to be laws? They give the whole answer, do they not?

In fact, there are lots of equations in biology, but you are right David, they do not give us the whole answer. They show us what happens in very specific situations that usually don't exist. ha! ha! example: Hardy Weinberg Equilibrium and Punnett squares....

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Even if biology doesn't have laws, there must be things that are not termed "theory". For instance, (say) the process of photosynthesis isn't termed a theory (I hope this is a good example). So, what is different about evolution? Is it the fact that we have not directly observed evolution?

I have no idea about the moth example, mentioned above, but if one were able to observe evolution taking place -- using a species that has life-times much shorter than humans -- would that (along with everything else) allow one to say that evolution is more than a theory?

I guess this comes down to the following: is there any sense in which we are less certain about evolution than we are about (say) photosynthesis?

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The question in the title contains a fallacy, and a very common one at that. It assumes that the theory of evolution can ever be anything other than a theory. It can't. Evolution is not called a theory because it does not have enough evidence to be a law. Theories do not become laws and laws were never theories. This is how my science teacher explained it:

A theory explains what happens and how or why it happens.

A law describes what happens.

An example of a theory is evolution.

What~ Animals evolved from common ancestors

Why/How~ Natural selection, mutation, genetic drift, etc.

An example of a law is the law of gravity.

What~ If you throw something up, it will come back down.

Why/How~ ...

Obviously I've oversimplified this, but anyway... Now, this is what I learned in science last year. If you want to take issue with it, go ahead. But as far as I know, law and theory are just two terms used to describe different forms of scientific data.

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Yeah, the law of gravity only says what happens. Newton's Law of Gravity: "Each object in the universe attracts each other body." Source There are also Newton's laws, which can all be expressed as equations, so I do think they only describe what happens. Let's see... There's also the gas laws, that translate into the equation PV=nRT. That also only describes what happens.

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I guess this comes down to the following: is there any sense in which we are less certain about evolution than we are about (say) photosynthesis?

The answer is no. And interestingly, the precise mechanisms of evolution have been known for much longer than for photosynthesis. Melvin Calvin did not discover how carbon dioxide was transformed into glucose until 1980 (he won a Nobel Prize for this). Although that is besides the point.

The reasons evolution is not accepted as a fact, or people think it is just a hypothesis, are complex. First, it is not very self-evident. I'm sure there are people that even deny the existence of gravity, and that is very self-evident! One needs a lot of preliminary knowledge in biology to fully understand evolution and all of its mechanisms. Even with that knowledge in place, many biology students cannot fathom the immense amount of time it takes for species to evolve. People think on an enormously smaller time scale, and evolution is highly conceptual. We all know how many people have trouble forming concepts!

Second, people perceive that evolution has philosophical implications, and their emotional reactions prevent them from being able to accept the facts. "You're telling me I descended from a MONKEY?"

The answer here is not that we have *not* directly observed evolution taking place. We *have* directly observed evolution taking place, and we have observed, over several centuries, through historical accounts, some new plant species evolve. I am not sure about animals, but I think there are a few examples. Of course, we have indirect evidence that all species evolved from one or a few forms.

Here is my answer - again, but hopefully more articulate this time - as to why evolution is not considered a law.

Consider the cell theory. Nobody will ever disprove it. It is a fact that life is made up of cells. However, in the world we live in, with all of the given physical laws, must life have evolved in the form of a cell? Must life have evolved at all? No. Given the same physical laws and combinations of elements and compounds, perhaps life would have evolved, perhaps not, and if it did, there is no guarantee that the cell would be the basic unit of life.

This is my educated guess as to why we do not consider any facts in biology to be laws. After all, the origin of life was an accident. (Its perpetuation is not.) There is no guarantee that if we started with an Earth exactly the same as what we had 6 billion years ago, that life would evolve in the same way, if at all. Life itself is not universal in space and time as are the physical laws (gravity, thermodynamics, etc.), and therefore, no theories predicting how life can behave or evolve can be considered laws.

No one has answered my question re: Einstein's theory of relativity. Doesn't this equation predict mass and energy with absolute certainty? If so, why is it still considered a theory? When has it ever been invalidated? It is has not, correct? It is because it does not assume that TIME is constant? Might this be why Einstein's theory is not considered a law? Because time changes with velocity?

just some thoughts.

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Thanks, Liriodendron. I'll no longer think of the word "theory" when I think of evolution.

Newton's Law of Gravity: "Each object in the universe attracts each other body."
Not to be obtuse, but I'm not convinced. For instance, take the concept "attracts". What does that mean? Does the Law of Gravity say that objects act as if they were attracted, or does it say that they do attract each other?

I would question the very idea that there is a fundamental distinction between what and how/why.

Suppose,

  • I observe A; and.
  • I observe that A is caused by B; and,
  • I am pretty sure that B is caused by C; and,
  • I speculate that C is caused by D

Then, I'd say that

  • I could have a law explaining the how/why of (A is caused by B)
  • I could have a theory explaining how/why (B is probably caused by A ... and we have no other viable explanations)
  • I could have a hypothesis explaining how/why (C might be caused by D)

The above are pretty rough; however, the point is that when I describe the how/why of something, I am doing no more than explaining what happens. I don't see a fundamental distinction.

The real distinction is (roughly) in the quantity/quality of evidence and thus the level of certainty.

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Doh! Wait - No, evolution is a theory AND a fact. Just don't think of it as an hypothesis. DO think of it as a theory, just as the fact that organisms are composed of cells is a theory.

I am no less certain of evolution, a theory, than I am of gravity, a law. But it cannot be a law because it is not a fundamental, unchangeable part of the universe. It is only a potential result of those fundamental parts. Life is not universal in space and time. There was a time when life did not exist (and there may be a time in the future when life does not exist), and there are spaces where life does not exist. All of the physical laws operate consistently throughout time and space, always have, and always will.

Physicists, am I correct? Someone help.

Evolutionary theory and cell theory only explain life as we know it, on Earth, since it originated. Since life is NOT a given throughout space and time, there can be no laws concerning it.

Edited by Liriodendron Tulipifera
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I don't know if I'd call it a "law" either. Not because of any lack of certainty, but because I am not sure that every fact is a law. Perhaps law is a specific type of identification of a causal relationship.

I will consider it a fact. However, I will not consider it a theory, because I think the concept "theory" addresses a specific aspect related to certainty and quality of proof. I do not think -- as you're implying -- that the concept "theory" relates to "inevitability" as implied by the question " Must life have evolved at all?". Cannot we ask, "Was it inevitable that there is a specific number of planets around the sun?"

The whole field of biology takes life as its starting point. Given that life exists, (and given that Biology exist), I think a biologist can say... these are the facts, these are the theories and these are the hypotheses about that life.

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I agree with what you said, but what do mean about "bad timing?" That we're just "not there yet" in predicting what happens in biological systems because there are too many factors to consider, but that we might be someday?
First, let me emphasize that I'm primarily addressing a PR question rather than an issue of substance/results. The problem of biological laws stems from the fact that in my ignorance of biology it seems to me that it's not generally possible yet to give symbolic equations stating quantitative relationships between measurements of the kind you find in physical science (Fg = G((m1*m2)/r^2)). How about some free biology education -- can you explain one or two proven equations of biology? I'll leave out there part where you explain it so that everybody in the country gets it. The other significant factor in the "bad timing" problem is the death of law. I'm serious about that -- I think the concept of "scientific law" is kind of old school (regrettably so). If you could take a future version of biology where we know orders of magnitude more, and transport the discovery of these things back in the mid-19th century, you could have scientific laws. But nowadays, it seems, science more has models and their refinements.
Anyway, why aren't Einstein's equations re: relativity considered to be laws? They give the whole answer, do they not?
I have seen it said (click, click), and there's nothing in principle to keep people from speaking of "Einstein's Mass-Energy Law" (see W. Wilson 1936 "The mass of a convected field and Einstein's mass-energy law" Proc Phys. Soc 48: 736-740). But I think there has been a significant change in attitude about scientific knowledge over the past 100 year or so, and people are less willing to embrace the concept of certainty the way they used to. This translates into fossilized concepts for the masses: hard science has absolute laws (which we know are right), biological science has theories (which we are not certain are right). A lot of people get flummoxed over issues of certainty.
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Here is my understanding of the terms:

A theory is a large body of information which synthesises lots of different observations in some domain of knowlege, and also provides an explanation of how and why these observations occur (usually by postulating theoretical entities which have casual powers). Although we have a "law of gravitation", this is just a description of how objects falls - it doesnt give information why they fall. But we also have a theory of gravity (general relativity) which does offer such an explanation. Similarly, we have the theory of quantum mechanics, quantum field theory, and exotic things like string theory and various theories within cosmology. All of these theories postulate a significant number of theoretical entities in order to explain various things which we have observed - ie to unify our observations and provide some kind of causal/explanatory basis for them.

A law, on the other hand, is a single statement - a description of something that occurs, rather than an explantion. It will also certainly presuppose some body of theory, simply because all observations are theory-laden to some degree. It will be expected that law-like statements will always hold. So although you wouldnt ever have a 'law of evolution', you could claim that some specific statements within evolutionary theory were law-like to the extent that they were fundamental to the theory, and that you were fairly certain that they would always hold. So you could say that you had a 'law of natural selection', which held that "over a sufficient number of generations, a group of creatures in an enviorment with limited resources will produce desendents with high degrees of fitness relative to that environment" or something like that. This would maybe start out as a postulate, but become a law as more and more confirming instances were observed. But the distinction between observation, postulate and law isnt very rigid.

In other words, theories are very broad synthesis of many different observations and postulates in some domian of science. Laws are specific generalisations about some aspect of nature. Or to put it another way, laws describe what nature does, whereas theories offer explanations of how/why nature behaves that way.

Not to be obtuse, but I'm not convinced. For instance, take the concept "attracts". What does that mean? Does the Law of Gravity say that objects act as if they were attracted, or does it say that they do attract each other?
Neither. It just describes a certain thing which happens in nature (masses cause other masses to accelerate, and this can be described quantatively by formula X). Theres no attempt at an explanation here - just the brute fact that this is what nature does. Why does nature do this? Well, you'll need a theory to explain that (such as general relativity).

I would question the very idea that there is a fundamental distinction between what and how/why.

[*]I observe A; and.

[*]I observe that A is caused by B; and,

[*]I am pretty sure that B is caused by C; and,

[*]I speculate that C is caused by D

'A' is a brute fact, whatever it is. If you find that A always happens, then you can have a "Law of A". But everything else that youve mentioned is part of your "Theory of A", which tries to explain why A occurs. You dont 'observe' that A is caused by B, you postulate that A is caused by B as part of your explanation/theory.

As you collect more and more evidence that A is indeed caused by B, C and D, it will become more and more rational to beleive the theory is true until you reach some point where doubting it becomes pointless. And then you'll have an accepted scientific theory. But it still wont be a law - you'll still have a "Law of A" which states that A occurs, and a "theory of A" explaining why. It might happen that someone will later come along and show that your theory is wrong and that A actually happens as a result of E, F and G, but the "Law of A" will still hold.

edit: to put it another way: once you have made your observations and formulated the law of A, this law cant be shown false unless additional empirical information is found. If you observe A, then A happens and thats the bottom line. In order to show that the "Law of A" doesnt always hold, you would have to actually go out and find some circumstance where A doesnt occur. But theories arent like this - a theory can be replaced by a better theory without any new observations occuring, simply because the new theory is simpler or has more explanatory power. Imagine youve given an explanation of why A occurs. But now, someone else comes along with an explanation which is simpler than yours, makes fewer assumptions, and also unifies A with other observed phenomenon M, N and P. It would then be rational for you to abandon your theory of A and support his, even though your theory isnt incompatible with the evidence. Its just been replaced by a better explanation.

Edited by Hal
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How about some free biology education -- can you explain one or two proven equations of biology?

I think the predator-prey model has been pretty successful in various areas. Its a system of differential equations which describes how a population will evolve, if it contains some members which prey on the others (eg, a population of ducks and wolves). I assume theres other quantative models within mathematical biology that I dont know about (since the field probably wouldnt exist otherwise).

However, applying models like this to the real world can be difficult because you have so many different factors involved once you remove the idealised conditions of the laboratory. A similar problem can occur in a highly mathematical theory like Newtonian mechanics - although paradigm applications involving small systems of balls and pendulums are easily solvable, things become far far harder when you consider more complex systems like the three body problem in gravitation or turbulent systems in fluid dynamics, where you have to take things like chaos theory into account. It gets worse when you start looking at theories which involve more serious mathematics - solving a problem in quantum electrodynamics for a system containing more than a handful of particles would be computationally infeasible.

Its easier to formulate simple laws when you are looking at an idealised spring in a laboratory, than when you are trying to see how a highly complex biological system functions. Thereotical physics tends to involve a lot of idealisations where you get to consider systems 'in isolation' from the rest of the world, which is why you get nice and simple mathematical laws (which cant always be used to predict 'real-world' systems because of the heavy amounts of computation which gets added by increased complexity - hence why we need higher level disciplines like chemistry and biology rather than just predicting everything from first-principles in physics).

Edited by Hal
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Nowadays, it seems, science more has models and their refinements.I have seen it said (click, click), and there's nothing in principle to keep people from speaking of "Einstein's Mass-Energy Law" (see W. Wilson 1936 "The mass of a convected field and Einstein's mass-energy law" Proc Phys. Soc 48: 736-740). But I think there has been a significant change in attitude about scientific knowledge over the past 100 year or so, and people are less willing to embrace the concept of certainty the way they used to. This translates into fossilized concepts for the masses: hard science has absolute laws (which we know are right), biological science has theories (which we are not certain are right). A lot of people get flummoxed over issues of certainty.
I think this is partially semantics. To my knowldge, the basic principles of modern physics are still considered to be laws, although they dont have catchy names. We could call the uncertainty principle "Heisenberg's law of uncertainty", but it doesnt really matter either way - most physicists are still pretty certain that its always going to hold even if it doesnt have 'law' in its name. Similarly, you could refer to the postulates of quantum mechanics as being the laws of quantum mechanics, but this might perhaps be misleading since they arent 'observational' in quite the same sense that paradigm classical laws are. But you still have conservation laws in quantum physics such as the partial conservation of spin/strangeness etc.

You could be right that modern developments in the philosophy of science have caused people to become less enthusiastic about explictly labelling things as being 'laws'. I'm not entirely sure, but its an interesting idea.

edit: Actually I'm not sure about that. Heisenberg's uncertainty principle is in a certain sense a priori (ie it drops out of the mathematical formalism) rather than being an empirical generalisation.

Edited by Hal
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I think the concept of "scientific law" is kind of old school (regrettably so). If you could take a future version of biology where we know orders of magnitude more, and transport the discovery of these things back in the mid-19th century, you could have scientific laws. But nowadays, it seems, science more has models and their refinements.

I see what you are saying now (I think). Is it that people back then had a different philosophic mindset, whereas today they do not have that mindset that leads them to think there is certainty in the world?

I actually think in biology that we have a little too much certainty, even without the laws. Perhaps this is not a problem with laws or theories, per se, but with people just not thinking. For example, the Central Dogma, which states the DNA is transcribed into RNA which is translated into protein, has around since the 70s, and unfortunately, it really it got in the way of peoples' thinking when it came to prions (those protein things that cause mad cow disease), which somehow reverse-translate into DNA (I think, I'm not totally sure on this but it's something like that - either that or RNA). The rules should be there, but too often people do not think outside the box to refine the rules or the theories. Theories in biology, at this point, still need refinement.

Anyway, there I go talking about models and refinements! :P

Edited by Liriodendron Tulipifera
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I see what you are saying now (I think). Is it that people back then had a different philosophic mindset, whereas today they do not have that mindset that leads them to think there is certainty in the world?
Yes: I think skepticism (in the nihilistic sense) has more influence in science that in the Golden Era, and especially in popular versions of science. Now BTW in speaking of certainty, I'm referring to the Peikovian sense, and not a "feeling". The first thing I reject is feeling-based certainty; the second thing I reject is feeling-based uncertainty. We in linguology have various Central Dogmata, too many of which cannot be robustly supported by massive empirical evidence but are ideas that are too good to be false, so I empathise when it comes to the DNA/RNA problem. I always try to reduce these arguments to the question "What observations support this conclusion", and I find it interesting how people have a hard time relating conclusions to evidence.
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But you still have conservation laws in quantum physics such as the partial conservation of spin/strangeness etc.
Right, but laws of conservation of energy, mass, linear and angular momentum and charge are old school, and conservation of strangeness is, I think, more by analogy to classical conservation, which goes back to Leibniz / Newton days.

The difficulty of applying basical physical laws to complex situations is a good explanation for why it's hard to believe in biological laws with the same degree of confidence as with gravity. If there were analogous simple cases where laws of biology could be resoundingly verified, it would be easier to believe that the more complicated cases are "more of same". Since biology is much more complex, you don't have the base of rational certainty that (for better or worse) results in confidence that the basic principles will apply to more life-like cases.

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For example, the Central Dogma, which states the DNA is transcribed into RNA which is translated into protein, has around since the 70s, and unfortunately, it really it got in the way of peoples' thinking when it came to prions (those protein things that cause mad cow disease), which somehow reverse-translate into DNA (I think, I'm not totally sure on this but it's something like that - either that or RNA).

RNA, I thought. Apparently in the last five years or so it's been found out that long-term memories seem to be stabilized that way. One (or maybe more) of the proteins that stabilize synapses has a prion configuration that causes transfer RNA to produce more of the protein. There's an article about it here if you're curious.

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Does this help?

"2. Isn't evolution just a theory that remains unproven?"

"In science, a theory is a rigorously tested statement of general principles that explains observable and recorded aspects of the world. A scientific theory therefore describes a higher level of understanding that ties "facts" together. A scientific theory stands until proven wrong -- it is never proven correct. The Darwinian theory of evolution has withstood the test of time and thousands of scientific experiments; nothing has disproved it since Darwin first proposed it more than 150 years ago. Indeed, many scientific advances, in a range of scientific disciplines including physics, geology, chemistry, and molecular biology, have supported, refined, and expanded evolutionary theory far beyond anything Darwin could have imagined. "

From PBS

http://www.pbs.org/wgbh/evolution/library/faq/cat01.html#Q02

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A scientific theory stands until proven wrong -- it is never proven correct.
I think that muddies the picture, because it's not true that a scientific theory cannot be proven. However, I don't know enough about the specific claim (non-popular, hard-core science) of evolution or the supporting evidence to be able to judge whether it rises to the level of proven (as opposed to Boyle's Law, concervation of charge, or the resonant frequency of a Helmholtz resonator).
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Are transitional animals "missing" as palentologists say [based on net search] and thus there is no case for macro evolution? There is case for micro evolution .

1) Are transitional animals really missing?

2) Are presence of transitional animals required to make the case for macro evolution?

3) Do palaentologists really say there are NO transitional animals?

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Are transitional animals "missing" as palentologists say [based on net search] and thus there is no case for macro evolution? There is case for micro evolution .

1) Are transitional animals really missing?

2) Are presence of transitional animals required to make the case for macro evolution?

3) Do palaentologists really say there are NO transitional animals?

This is probably the wrong forum for this sort of question, since it relates to technical issues of science rather than philosophy. From the style of question, I suspect youre trying to refute specific claims by creationists rather than expressing a genuine interest in learning the fine details of evolutionary biology, so I would recommend www.talkorigins.com which deals with that sort of thing.
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This is probably the wrong forum for this sort of question, since it relates to technical issues of science rather than philosophy. From the style of question, I suspect youre trying to refute specific claims by creationists rather than expressing a genuine interest in learning the fine details of evolutionary biology, so I would recommend www.talkorigins.com which deals with that sort of thing.

Actually I was hoping to run into some persons with the hands on knowledge on the questions raised. If there are some persons out here who happen to know, shoot me a reply here. It will be appreciated.

I tend to lean towards Karl Popper [ noted , deceased, philosopher of science] who views evolution as a science and as a [scientific] fact and also as a metaphysical research progam. The recently deceased Harvard palentologist did quote Popper in some of his works but I have forgotten the fine details of what I thought was an out of context quote. It could be that he cited Popper for the first point but omitted the second point on metaphysical research program.

Again, issue of whether it is in or out of context, if some persons or any person has hands on knowledge, please reply. If not, thanks

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1) Are transitional animals really missing?

2) Are presence of transitional animals required to make the case for macro evolution?

3) Do paleontologists really say there are NO transitional animals?

(I am not an expert, but this is my understanding.)

1. It is not the animals which are "missing", it is their fossils. The fossil record has many gaps in it for a number of reasons, including: some organisms' remains do not fossilize well (too soft or wrong chemistry); they may have been destroyed (by predators or scavengers or bacteria) or dispersed (so that no reconstruction can be done); the stratum in which the fossils were deposited may have been eroded away or subducted into the mantle or melted or otherwise destroyed; the stratum may be buried where we cannot find it; the fossils may not have yet been recognized for what they are; or the intermediate forms may have evolved so rapidly that they left too few remains to be discovered.

2. Actually there are many transitional forms in the fossils. It is just not a complete continuum. The existence of the many which do exist is evidence of evolution. But it is also true that we can watch evolution taking place around us in our documented history. Many species, like the Dodo bird, have gone extinct. Species have invaded new habitats and begun to diversify into new forms. We also have evidence from DNA and other biological chemicals that all known species are related to each other to varying degrees, i.e. they all have a common ancestor.

3. NO! See:

http://www.fossilmuseum.net

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