Evidence God Is

[David T]

I don't agree, and the court in the Dover trial 2005 didn't agree either, ruling that ID was just a mask for creationism with fingers crossed that it could avoid the pre-existing rulings of SCOTUS and be taught (as "science"! unbelievable!) in schools.

The Intelligent Designer has to be God, and since its proponents are Creo Christians, the Creo Christian God. If the ID is not a god then ID doesn't propose a solution, merely an infinite regression: how did the ID evolve to the point where it could get into the ID business, when humans can't? Their evolution must have been modified by an earlier ID, who not being God, must have evolved with the assistance of an earlier ID, who not being God, must have &c &c &c.

Well it has zero to do with the bible it exists regardless and independent of the bible. Its a particular theory of virtual reality and simply uses the bible as its lame *** excuse of what it believes is actual understanding of nature and the bible virtually.

Its neither or, are you proposing ID people are brilliant and do understand the bible? By what means exactly? magic? An idiot is an idiot regardless. Dont give ID ANY CREDIT!.

By default all forms of virtual reality theories regardless in either science or religion are crackpot nonsense and thats all we are talking about not that difficult actually ... We are Virtually discussing it via writing.

 

[blü 2]

Dont give ID ANY CREDIT!.

Trust me on that one.

 

[Cacotopia]

I'm tired of reading "look at the birds look at the trees, look at how complex life is, it must be designed by a super intelligent deity, but that deity wasn't designed be an even more complex deity."

Your idea includes the flaw of infinite regression, where you will break rules of your own theory for your god specifically.. He is so complex he made himself? You are trying to be rational, but you will be irrational when someone else applies your rationale to your god. It happens every single time.

with
out
fail

I am simply well beyond my bs-o-meter limit on this argument. If we had discussed this about 12 years ago I might be more civilized about it.

 

[nPeace]

Do you wish to discuss how the evolutionary process satisfactorily explains the origins and subsequent development of the nervous system? I am happy to discuss this. Would you like me to start a new thread on that specific topic? I worry that this thread has too many divergent conversations going and will distract from a sustained discussion on the subject.

What do you mean by discuss? Do you mean, do I want someone to teach me what they think I don't know? Or do you mean do I wish to have a two way discussion about the explanations scientists give?

You can decide if you wish to start a new thread.
Are you on this thread to discuss how the evidence presented is the OP satisfactorily supports the existence of a creator? Or are you interested only in presenting an argument for evolution?

I can meet you halfway, but I am not about to go on another one track ride.
The last discussion I had with someone where a teaching approach common on these forums, was employed, caused the cart to run off the track.
In other words, a discussion is two way. That means that one person doesn't take it upon themselves to ask questions, and avoid answering questions, or present arguments while ignoring counter arguments.
If your approach is different, that might work.

Already, though, it looks a bit like the common approach.
For example, instead of addressing the argument in the OP, which seems to me a strong argument, you have not made any effort to counter it, or show why it is not a good argument, if you think it isn't.
Rather you make a case for evolution being believable.

Biological evolution is a wholly satisfactory natural process that explains the existence of all these things you mention here. These are all examples of agent-less natural and spontaneous emergence of complex and functional systems. The evidence for this is vast and overwhelming, if one chooses to know about them.

Okay, so you don't want to discuss the argument in the OP. I flexed because you touched on something I mentioned.
I responded by making a few points, with a few questions. Perhaps you didn't acknowledge them because you wanted to discuss something else, but once again, you make a case for evolution being believable, by suggesting discussing how the evolutionary process satisfactorily explains stuff.

I don't know your intentions... You will have to tell me, but consider how it might look to me.
It looks to me, as though we started on a one track ride already.
I'm not looking to have things my way. I just believe in fair debate/discussion - two way.

I think on a debate forum, one should feel free to present information, which they think will be a good counter argument to a presented argument.
I also think one should feel free to create a thread with an argument that challenges another's post.
I see persons doing that, and I think that does well for debate forums.
So I am all for that.

When you present your argument say, for evolutionary explanation for what you believe is so believable.
I will ask questions, which I think it's fair my questions are addressed. Would you agree?
I'll let you know these questions in advanced, and why it's important they be considered.
:
How do scientists arrive at their explanations?
Much of the evidence is arrived at by assumptions, suppositions, interpretations, inferences,... is that not true?
Many of these are not universally accepted, but are declared as the best explanation, true?
What makes this evidence any different to what others have... is it because certain methods are applied?
If the methods applied makes it so good, why are there disagreements, and different theories proposed, and realizations that the suppositions were wrong?
It is not that the evidence suddenly spoke in a voice, and told the story. Is it?
There are more questions, but I'll save them.

Long and short of it, scientists observe things, and arrive at conclusion in the same way anyone else does.
There is no direct evidence. When there is no direct evidence, we have to use reasoning, logic, and make inference from the evidence we have.
Circumstantial evidence does not only tell one story.
Because persons declare their evidence to be the best explanation, does not mean they are right. Is that not so?

We have not directly seen a creator at work, but there is evidence that allows us to infer that life was created by an intelligent designer.
I have presented just some of that evidence in this thread with the intent that it would meet, and stand up to the best argument against it. There is a reason why it holds.

I hope my explanation was clear and understandable.
My previous experiences have been as I said before; persons just ignore my questions, and make silly excuses for doing so, or evade answering them by various methods.
If you are willing to address them, but don't want to do it in this thread, then by all means, feel free to go ahead and create a new thread - I will respond.

Magic is the altering of reality independently of the rules of physics, usually just by wishing. Miracles are therefore a subset of magic.

So if I assume that nothing brought forth something would you consider that magic?

Moving relative to what?

Does anything move without a force having acted on it?

If I were in that position, and uncomprehending, I'd put it down to my ignorance, not to magic. Magic is essentially not credible, there being not one authenticated example anywhere, so you have to exhaust all the other options, even the most grossly improbable ones, before magic can be the answer.

I'm not quite sure what you mean, but I guess it could be the supposition of magic. I don't see any way it could actually be magic.

Depends what you mean by a designer. As for inanimate things, should we think that every snowflake is designed and made by some tiny sentient master-craftsthing with nothing better to do? As for living things, evolution is well described, its conclusions constantly tested and retested, and evolution accounts for the fact that particular living things have the particular qualities they do. We know why flowers gain from being colorful, why surviving long enough to reproduce is the central essential of life, why humans bond, and the biochemicals involved, and so on ─ no designer needed at any point.

Things like inflation, natural selection... are nothing more than fairy godmothers or genies conjured up to poof away problems.

The Inflation Theory proposes a period of extremely rapid (exponential) expansion of the universe during its first few moments. It was developed around 1980 to explain several puzzles with the standard Big Bangtheory, in which the universe expands relatively gradually throughout its history.

Observed? No, but they work to give the story a smooth transition, until another hiccup pops up... Then we invoke another genie, or fairy.

Is The Inflationary Universe A Scientific Theory? Not Anymore
We are made from stretched quantum fluctuations. At least that’s cosmologists’ currently most popular explanation.

Evidence for Cosmic Inflation Theory Bites the (Space) Dust
It is the announcement no one wanted to hear: The most exciting astronomical discovery of 2014 has vanished. Two groups of scientists announced today (Jan. 30) that a tantalizing signal — which some scientists claimed was "smoking gun" evidence of dramatic cosmic expansion just after the birth of the universe — was actually caused by something much more mundane: interstellar dust.

Then to claim that Christian are employing magic, because they are using observation, experimentation, reasoning and logic, outside of a lab, and lab coat, to me seems quite absurd.

What is the point regarding design?
Unfortunately I have to get back to you later on this, since I am straining my eyes to see what I am reading and writing. So I will return to this hopefully later.

 

[Milton Platt]

I've just read the entire letter, written to philosopher Erik Gutkind. It can be found here:
Letters of Note: The word God is the product of human weakness

The context is speaking entirely about the Jewish Religion and their monotheism of a personal God.
With one reference to Spinoza.

It in no way contradicts his opinions of a 'superior reasoning power.'

So a superior reasoning power that is not a god? What would that be?

 

[sayak83]

What do you mean by discuss? Do you mean, do I want someone to teach me what they think I don't know? Or do you mean do I wish to have a two way discussion about the explanations scientists give?

You can decide if you wish to start a new thread.
Are you on this thread to discuss how the evidence presented is the OP satisfactorily supports the existence of a creator? Or are you interested only in presenting an argument for evolution?

I can meet you halfway, but I am not about to go on another one track ride.
The last discussion I had with someone where a teaching approach common on these forums, was employed, caused the cart to run off the track.
In other words, a discussion is two way. That means that one person doesn't take it upon themselves to ask questions, and avoid answering questions, or present arguments while ignoring counter arguments.
If your approach is different, that might work.

Already, though, it looks a bit like the common approach.
For example, instead of addressing the argument in the OP, which seems to me a strong argument, you have not made any effort to counter it, or show why it is not a good argument, if you think it isn't.
Rather you make a case for evolution being believable.

Okay, so you don't want to discuss the argument in the OP. I flexed because you touched on something I mentioned.
I responded by making a few points, with a few questions. Perhaps you didn't acknowledge them because you wanted to discuss something else, but once again, you make a case for evolution being believable, by suggesting discussing how the evolutionary process satisfactorily explains stuff.

I don't know your intentions... You will have to tell me, but consider how it might look to me.
It looks to me, as though we started on a one track ride already.
I'm not looking to have things my way. I just believe in fair debate/discussion - two way.

I think on a debate forum, one should feel free to present information, which they think will be a good counter argument to a presented argument.
I also think one should feel free to create a thread with an argument that challenges another's post.
I see persons doing that, and I think that does well for debate forums.
So I am all for that.

When you present your argument say, for evolutionary explanation for what you believe is so believable.
I will ask questions, which I think it's fair my questions are addressed. Would you agree?
I'll let you know these questions in advanced, and why it's important they be considered.
:
How do scientists arrive at their explanations?
Much of the evidence is arrived at by assumptions, suppositions, interpretations, inferences,... is that not true?
Many of these are not universally accepted, but are declared as the best explanation, true?
What makes this evidence any different to what others have... is it because certain methods are applied?
If the methods applied makes it so good, why are there disagreements, and different theories proposed, and realizations that the suppositions were wrong?
It is not that the evidence suddenly spoke in a voice, and told the story. Is it?
There are more questions, but I'll save them.

Long and short of it, scientists observe things, and arrive at conclusion in the same way anyone else does.
There is no direct evidence. When there is no direct evidence, we have to use reasoning, logic, and make inference from the evidence we have.
Circumstantial evidence does not only tell one story.
Because persons declare their evidence to be the best explanation, does not mean they are right. Is that not so?

We have not directly seen a creator at work, but there is evidence that allows us to infer that life was created by an intelligent designer.
I have presented just some of that evidence in this thread with the intent that it would meet, and stand up to the best argument against it. There is a reason why it holds.

I hope my explanation was clear and understandable.
My previous experiences have been as I said before; persons just ignore my questions, and make silly excuses for doing so, or evade answering them by various methods.
If you are willing to address them, but don't want to do it in this thread, then by all means, feel free to go ahead and create a new thread - I will respond.



So if I assume that nothing brought forth something would you consider that magic?


Does anything move without a force having acted on it?


Things like inflation, natural selection... are nothing more than fairy godmothers or genies conjured up to poof away problems.

The Inflation Theory proposes a period of extremely rapid (exponential) expansion of the universe during its first few moments. It was developed around 1980 to explain several puzzles with the standard Big Bangtheory, in which the universe expands relatively gradually throughout its history.

Observed? No, but they work to give the story a smooth transition, until another hiccup pops up... Then we invoke another genie, or fairy.

Is The Inflationary Universe A Scientific Theory? Not Anymore
We are made from stretched quantum fluctuations. At least that’s cosmologists’ currently most popular explanation.

Evidence for Cosmic Inflation Theory Bites the (Space) Dust
It is the announcement no one wanted to hear: The most exciting astronomical discovery of 2014 has vanished. Two groups of scientists announced today (Jan. 30) that a tantalizing signal — which some scientists claimed was "smoking gun" evidence of dramatic cosmic expansion just after the birth of the universe — was actually caused by something much more mundane: interstellar dust.

Then to claim that Christian are employing magic, because they are using observation, experimentation, reasoning and logic, outside of a lab, and lab coat, to me seems quite absurd.

What is the point regarding design?
Unfortunately I have to get back to you later on this, since I am straining my eyes to see what I am reading and writing. So I will return to this hopefully later.

If I show you that natural processes can create designed and functional systems, then your OP argument that all designed things need an agent like designer is refuted. That's the simple case I wish to make.

 

[blü 2]

So if I assume that nothing brought forth something would you consider that magic?

If there were such a phenomenon in reality and that was your explanation for it, I'd consider it a magical explanation, yes. (That's why, for example, I think at least energy must have pre-existed the Big Bang.)

Does anything move without a force having acted on it?

Gravity isn't technically a force, so yes.

Things like inflation

There's debate about inflation, as you may know.

natural selection... are nothing more than fairy godmothers or genies conjured up to poof away problems.

Really? Natural selection doesn't happen, you say? The creatures whose genes best equip them to survive in environment X are NOT the one who get to pass on their genes more often than their less equipped fellows in environment X, you say? If you're right, that should be worth a paper or two in Nature, no?

Then to claim that Christian are employing magic, because they are using observation, experimentation, reasoning and logic, outside of a lab, and lab coat, to me seems quite absurd.

On the contrary, my observation is that we have not a single authenticated example of magic on the books so I assert inductively that magic isn't found in reality. Therefore not even Christians can employ it. And it would not be wise to assert it as an explanation for any natural phenomenon unless and until we have a satisfactory demonstration of its reality and a well-tested hypothesis as to how it works. Until then it's not capable of explaining anything.

 

[Kelly of the Phoenix]

I truly admire, and marvel at the intelligence of animals, but do you believe that they have the consciousness that humans do?

Some do. Of course, I can probably find animals smarter than many humans too.

For example, do you think they are concerned about questions such as, "Why are we here? Where are we going? What happens if we die? Can we live again?" ... and other questions of that nature?

What if the questions are irrelevant? IIRC it's irrelevant in Buddhism. There are human religions that think those questions are beside the point.

Why would “naturalistic evolution” create brains that wonder about the existence of God, the meaning of life, the origin of the universe and other selectively useless stuff?

It helps when one realizes gods were not always eternal omni-omni cosmic beings, but just some super-powered entity (human or otherwise).

Humans honored their leaders/role models. Then they deified them.

Why do we die? Why is death a natural or normal occurrence?

Eventually the body can't cope with a lifetime of stressors, internal or external. Immortality ain't what it's cracked up to be. Ask Eos.

So why did evolution and natural selection select unecesairly complex brains capable of wondering about useless philosophical stuff?

Philosophy is a luxury. People desperate to eat the next meal won't be bothered with such things.

How often do people pray for some philosophical insight? It's mostly "let the light turn green" or "that dollar bill on the sidewalk means I can pay my grocery bill" or "please don't let me be shot". Look at Jesus' audience: most of them were there for the free healthcare. No one really cared about his teachings.

If naturalism (and darwinism) where true, humans would not be capable of wondering about useless philosophical stuff

They would if various factors limiting their time were removed.

Ben Franklin was a great thinker. He had slaves doing all the dirty work, which is why he had plenty of free time.

It seems to me God is predominately indifferent.

Even Jesus agrees, when he notes it rains on the good and bad alike. The bible often lets slip that God's just not that into you.

While humans (A&E) were living in a utopian world, God's Sovereignty was challenged: A&E were told they could make their own decisions, and not have to listen to Jehovah God. When A&E chose to disobey, they gave the issue validity.

It makes sense, though. We were formed in God's image. God apparently didn't like what He saw in the mirror, hence all the hostility.

Jehovah has stayed out of human affairs, even removing His control over Earth's geologic and weather systems.

Then He doesn't get credit for anything that happens here. He doesn't get to be negligent AND get the cookie.

He has given us a letter, i.e., the Bible

For many millennia, there was no bible. What was God waiting for? And why pick a medium that only a handful of people anywhere on the globe could accomplish? It's not like everyone could read. Seems like a horribly stupid plan of action, to me.

Psychiatry Online

He has stayed away, allowing His alienated children to rule themselves

And that's why life has gradually increased in longevity and healthcare and stability and ....

Remember, God doesn't get to take the credit for our successes since He insists on being negligent.

https://one-elevenbooks.com/the-neglectful-mother/

My argument is that humans are curios creatures who what to learn stuff, just for the sake of learning, for example scientists what to understand what dark matter is, just because they are curios. Agree….yes or no?

And many people's last words were "hey, look what I can do".

 

[Hockeycowboy]

Then He doesn't get credit for anything that happens here. He doesn't get to be negligent AND get the cookie.

How is He, "negligent"?
Those issues raised, were best settled by allowing man to rule himself, not interfering with it. So, He has stayed out of it. But, He didn't leave us on our own! He's provided a wonderful letter (the Bible) for us, which tells us not only how to act (like @ Philippians 2:3-4 & Colossians 3:12-14), but tells us how we can get His help when we need Him. (Matthew 11:22; Mark 11:24; James 1:5-6).

But then, I'll hear, "prayer don't work!"
Well, 1 John 3:22 to them..... "and whatever we ask we receive from him, because we keep his commandments and do what pleases him." (ESV.com)

See the stipulation? If they ain't gonna listen to begin with, why should He help?!

 

[Hockeycowboy]

Gravity isn't technically a force, so yes.

"According to the present understanding, there are four fundamental interactions or forces: gravitation, electromagnetism, the weak interaction, and the strong interaction. Their magnitude and behaviour vary greatly, as described in the table below."

Fundamental interaction - Wikipedia

It's a force. They all are.

 

[blü 2]

"According to the present understanding, there are four fundamental interactions or forces: gravitation, electromagnetism, the weak interaction, and the strong interaction. Their magnitude and behaviour vary greatly, as described in the table below."

Fundamental interaction - Wikipedia

It's a force. They all are.

Gravitation is due to the curvature of spacetime (Einstein 1915). It's distinct from the EM, strong and weak forces. Though yes, they're often put forward as four forces.

 

[leroy]

Everything yes but the godless comment. Natural selection could be gods way of creation, true?

Creation doesn't need the supernatural to be an act of God.

ok so if you say yes to everything it follows that under naturalism we shouldn't have that type of curiosity. But we we do have it. Therefore naturalism is probably wrong

Sure, God could have guided the process In this case the ultimate goal might not be "survival of the fittest" so we coul have these brains and this type of curiosity

 

[leroy]

General curiosity would certainly be a useful trait as it would assist in knowing about one's environment.

Various traits are side effects of useful ones. For example, infants learning from parents, while necessary for practical matters, also makes them vulnerable to scams like religion.

Your argument is specious.

Well if our hability and interest in wondering about useless stuff is just a side effect the you shouldn't trust your brain when you wonder about these stuff.

The conclusion "atheism is true " was made by a brain that is not suppose to be reliable.

 

[Unveiled Artist]

ok so if you say yes to everything it follows that under naturalism we shouldn't have that type of curiosity. But we we do have it. Therefore naturalism is probably wrong

Sure, God could have guided the process In this case the ultimate goal might not be "survival of the fittest" so we coul have these brains and this type of curiosity

After reading this again (was early when I read it) is say no to the last two:

This type of curiosity is selectively useless, (understanding dark matter would not make our specie better in surviving and reproducing) agree? yes or no?

-thats not the purpose of curiosity. Curiosity doesn't need to be related to your survival. There are many motivations to be curious. So, no. Not useless. I don't see any form of curiousity useless. I'm sure many know that to solve a problem they need More Than just being curious; I'm sure people can tell the difference between relationship with curiousity and survival,Etc.

“Godless Natural selection” is unlikely to select an attribute that is useless and consumes a lot of energy agree? Yes or no?

What?

If you grant these points it follows that the human brain, who has these type of curiosity, is not likely to evolve by a mechanism of “Godless Natural selection”

You're making this complicated. Are you saying the complexity of the brain cannot evolve without god?

Are you saying naturalization cannot make a complex brain without god?

That does not make sense. Naturalization is part of human complexity from the formation of the brain, how the mind works, seeing impulses that show the intensity of our thoughts in relation to our physiological responses.

Everything about us is purely for survival. From how we make sense if the world, raw interpretations based on preknowledge, a lot of things. The brain gets more complex (assuming a healthy brain) as we get older and less say through dementia when we die. I don't see it as a work of God. It's just life.

Whatever sacredness you want to attribute to the natural process to explain it in a more personal rather than material/cold way is your choice. The difference is it does not matter.

Why do you need to compare god to a godless concept (if you like) and degrade naturalism because it l, by definition not by choice, excludes god?

Is this word a threat to god focus creation and human complexity?

I'm trying to follow your reasoning.

 

[Dell]

In the beginning God created the heavens and the earth. - Genesis 1:1

According to the Bible, Jehovah Designed All Things
...

So... considering your presentation for evidence of ID, your presenting a logical some what scientific approach to why you believe there is designer. Thats good and your points scientifically debatable. But how do you sync it with the unrealistic unscientific accounts in the bible from where you get the designer. I.e..
1. A six day creation of the universe 6000 or so years ago.
2. Creation of Adam from clay and Eve from a rib.
3. A talking serpent, tree of life, and tree of knowledge of good and evil.
3. Death introduced on all life on earth from the fall of Adam and Eve.
4. A global flood and preservation of all life by a wooden ship holding 2 or 7 each of all animal and insect species.
5. All human civilizations on Earth from Noah's sons and wives. And an animal migration from Turkey to their present habitat.
6. Tower of Babel being the start of separation of human languages and races.

Present the same scientifical style evidence for the designer herself. You opened with "In the beginning God..." from the bible. Your trying to fit a square peg in a round hole by matching the two.

 

[QuestioningMind]

Why do you and I always seem to have a communication problem?
I mean, it happens every time.

I said it once. I said it twice. Here is the third time.
I said nothing about patterns.
Therefore, for you to say this makes absolutely no sense, and is not relevant.

If I never concluded any such thing, how could that statement apply to this thread.
If you want to discuss patterns, it's off the topic, so I am not interested. Please reread this post until you understand it, and revisit the OP. I think they are both clear.
Do you recall when we first met, how it went? This is a repeat.

When we get that cleared up, I'll be quite pleased to discuss your bad design argument, on the laryngeal nerve.

Yes... here we go again. I never said that YOU mentioned patterns. In my previous post I specifically stated that I'M the one who brought up patterns. What I said about patterns is that complex patterns exist in nature and that YOU are mistaking these complex patterns as some sort of evidence for intentional design. JUST like those tractor wheel patterns you mentioned in the dirt. It could be easy to see such complex patterns and conclude that the design was planned, yet such patterns are simply the result of random actions by the tractor's movements across the field.

 

[viole]

Okay good. What is design?


No, we don't all agree. Is that hard for you to believe.
If you are saying that you believe in design that has no designer, then it is not design.
Therefore, can you explain why there is construction, and functioning components, leading to a specified objective, or goal.

Natural selection does not account for the design. It does not, for example,address the function of reproduction, for it itself is not the construction, function, or goal, of the property.

It is rather a process that can be altered by various factors.
Those factors exist separately from natural selection.
Actually, natural selection would not exist, were there no design.

No design. No natural selection.
So back to point A we go. Design exists because there is a designer.

Who designed the first cause?
That argument, always seems to come up, where no other exists.
I suppose it sounds better that saying, processes got in motion without a mover.
So just imagine, everything is motionless, and then BOOM! something moves - no life, no intelligence, nothing.
Or maybe... there was life.

Evolution by natural selection is a very simple mechanism that can give the illusion of design.

And it is ridicolous to claim that there would be no natural selection without design.

Natural selection is the exact contrary of conscious design. The one that got a random advantage, depletes the resourses of the ones who did not and so his randomly acquired trait remains. And so on.

What is conscious about that?

Ciao

- viole

 

[Tiapan]

From naive point of view intelligent design seems the only possible answer, however closer examination of the actual small steps made over a fantastically long period of time shows normal natural processes achieve these amazing results as a part of their normal development. The flawed argument in intelligent design is a failure to see the range of natural biological experiments that succeeded (survival) and failed(extinctions) and gradual changes that eventually led to the current complex biological systems over time, they were definitely not an overnight finished product from day dot. With time, from small things big things grow, no need for intelligent designer. Accepting intelligent design ignores several centuries of scientific observations.
Cheers

 

[Rational Agnostic]

Evolution by natural selection is the solution to the problem of apparent design in living things, and it has no need for a god. If you are going to argue for the existence of God, using the first cause or "cosmological" argument makes more sense, as science has still not answered this question. But the argument from "design" is a lost cause, although I'll grant that living things are quite complex, which would lead someone unfamiliar with how natural selection works to believe they are designed by a conscious designer when they actually aren't

 

[nPeace]

Examples that show the so called satisfactorily explanations of scientific theories.
Warning! It's long, but it's useful.

Spoiler: Evolution Explanations

Where did bone come from?
Given that most primitive examples of mineralization belong to extinct lineages, for a long time our understanding of bone evolution was entirely based on the available fossil evidence. Only paleontology studies offered the possibility of gaining some insight into the ancient processes that led to mineralized skeleton; from the evidence available, it was surmised that the vertebrates were most likely descended from amphioxus-like forms with a notochord.

Skeletal evolution: different views
Given that primitive fossilized vertebral skeletons are scarce and that their remains often contain tissues that are difficult to classify, the emergence of the four skeletal tissue types (enamel, bone, dentine, cartilage) was controversial. While one hypothesis suggested that the four tissues all emerged early in vertebrate evolution, the other assumed a long time of tissue plasticity in early mineralized skeletons which preceded differentiation processes that came later on (Tarlo 1963, Halstead 1969). In addition, for many decades, synthesis of paleontological data was influenced by Ernst Haeckel's biogenetic law - that ontogeny recapitulates phylogeny - meaning that skeletons of ancestral adult vertebrates were assumed to be derived from cartilage, analogous to their embryonic skeletons (Hall 2003).

From outer to inner protection: design combined with fortuitous circumstances
So, how did mineralized tissues develop in the first place? What factors forced the first organisms to develop protective shields?
Following the violent moves of tectonic plates about 1.5 billion (1.5 × 109) years ago, huge amounts of minerals, including CaCO3, were washed into the oceans. This created the possibility for its inhabitants of developing hard body parts, such as shells or spines. At first, this helped unicellular organisms to cope with excessive amounts of minerals and to prevent over-crusting. It also led to the sharp increase in the diversity of multicellular organisms (and their fossils!) a little more than 0.5 billion years ago, known as the “Cambrian explosion” (Schopf 1994, Kawasaki et al. 2004). Furthermore, the appearance of a rigid outside skeleton extended the effective length of limbs, thus permitting more rapid locomotion in many organisms. The appearance of mineralized body parts is seen by many scientists as one of the forces that generally increased the pace of animal evolution (Kumar and Hedges 1998, Kutschera and Niklas 2004).

As much as exoskeleton added speed to the evolution of animal life in general and created opportunities for animals to expand their activity radius by using calcified extremities and protection shields, it also imposed limitations, associated mostly with limited body size and lack of surface sensory organs. In addition, rigid shells and shields did not allow much movement and locomotion; therefore, the next major change in the evolution of skeleton - dislocation of mineralized skeleton from the outside to the inside of animal bodies, proved to be a major adaptive advantage. Especially in animal lineages that later gave rise to vertebrates, the appearance of endoskeleton enabled the expansion of activity radius and habitation of entirely new environments (Bennet 1991). In addition, those developments encouraged the development of a strong muscular system and added further adaptive values such as greater overall mobility and the appearance of a regenerative and environment-sensitive outer dermis (Ruben and Battalia 1979, Ruben and Bennett 1980).

What came first: teeth or shield?
The earliest mineralized structures in the vertebrate lineage were tooth-like structures, odontodes. It is debated whether these emerged first in the throats of jawless, eel-like creatures with a notochord (conodonts), or as dental-like structures in the skin, arranged closely together to form a protective shield (Figure 1). In either case, it is obvious that predation and protection from predation was a driving force for this development (Figure 2). Modern theories suggest that it is not so meaningful to argue that teeth are the origin of dermal mineralization, or vice versa. Early teeth and the forerunners of bony skin plates appear to be the product of the same genetic machinery, regulating epithelial/mesenchyme interactions and able to produce similar structures at different locations. The machinery, involving BMPs, WNTs, and FGFs, was probably in place for other functions, e.g. forming sensory structures related to modern taste buds, and needed only modifications to enable formation of mineralized structures (Fraser et al. 2010). Thus, in modern animals, the RUNX transcription factors—which are crucial for bone formation—are also involved in the regulation of skin thickness and skin appendages such as hair follicles (Glotzer et al. 2008).

The next steps in skeletal evolution: from protective shields to endochondral ossification
The earliest skeleton in the vertebrate lineage was a non-collagen-based unmineralized cartilaginous endoskeleton. It was associated mostly with the pharynx, in taxa such as lancelets, lampreys, and hagfish . After the evolution of collagen II from earlier simple collagens, a collagen-based cartilage could form. In contrast to animals with completely non-collagenous skeletons, some of the primitive chondrichthyans (such as sharks) were able to form skeletal parts though the process of endochondral ossification; however, due to the lack of fossil record s, the exact time of origin and the extent to which this mechanism was used is unclear (Hall 2005 and references therein).

From an evolutionary point of view, endochondral ossification is the younger of the 2 types of bone formation (the older dermal bone was formed by intramembranous osssification). It occurs in vertebrate skeletons by replacement of cartilage templates. The process of endochondral ossification evolved gradually, starting with perichondral bone deposition using the molecular tools that had evolved during the evolution of bony shields in the skin. This preceded the evolution of processes of cartilage degradation and endochondral bone deposition, as shown mostly by studies on shark skeletogenesis (Mundlos and Olsen 1997, Eames et al. 2007).

In addition to delivering bone as an organ, endochondral ossification provided a structural support for vertebrate limb development. However, there is still debate and uncertainty concerning the transition from fish fins to vertebrate limbs. Did limbs first develop in aquatic animals, thus predisposing them to walk on land? Did digits appear in the water, or do they represent an adaptation to terrestrial environments? What was the original number of digits? The pair of limbs that came first, and also many details about their embryonic development are awaiting more definite answers (Hell 2005, and references therein). A recent study suggested that it is mostly the loss of the actinodin gene family (this family encodes proteins making up the rigid fibers of fins) which might explain how fish evolved into four-limbed vertebrates (Zhang et al. 2010). These authors' genetic experiments on zebrafish showed that it was probably a loss of only a small number of genes that acted as a creative force in evolution, accounting for the huge evolutionary transition from fins to limbs.

Exoskeleton Evolution
Further information: Small shelly fauna
On the whole, the fossil record only contains mineralised exoskeletons, since these are by far the most durable. Since most lineages with exoskeletons are thought to have started out with a non-mineralised exoskeleton which they later mineralised, this makes it difficult to comment on the very early evolution of each lineage's exoskeleton. It is known, however, that in a very short course of time, just before the Cambrian period, exoskeletons made of various materials – silica, calcium phosphate, calcite, aragonite, and even glued-together mineral flakes – sprang up in a range of different environments. Most lineages adopted the form of calcium carbonate which was stable in the ocean at the time they first mineralised, and did not change from this mineral morph - even when it became the less favorable.

Some Precambrian (Ediacaran) organisms produced tough but non-mineralized outer shells, while others, such as Cloudina, had a calcified exoskeleton, but mineralized skeletons did not become common until the beginning of the Cambrian period, with the rise of the "small shelly fauna". Just after the base of the Cambrian, these miniature fossils become diverse and abundant – this abruptness may be an illusion, since the chemical conditions which preserved the small shellies appeared at the same time. Most other shell-forming organisms appear during the Cambrian period, with the Bryozoans being the only calcifying phylum to appear later, in the Ordovician. The sudden appearance of shells has been linked to a change in ocean chemistry which made the calcium compounds of which the shells are constructed stable enough to be precipitated into a shell. However this is unlikely to be a sufficient cause, as the main construction cost of shells is in creating the proteins and polysaccharides required for the shell's composite structure, not in the precipitation of the mineral components. Skeletonization also appeared at almost exactly the same time that animals started burrowing to avoid predation, and one of the earliest exoskeletons was made of glued-together mineral flakes, suggesting that skeletonization was likewise a response to increased pressure from predators.

Ocean chemistry may also control which mineral shells are constructed of. Calcium carbonate has two forms, the stable calcite, and the metastable aragonite, which is stable within a reasonable range of chemical environments but rapidly becomes unstable outside this range. When the oceans contain a relatively high proportion of magnesium compared to calcium, aragonite is more stable, but as the magnesium concentration drops, it becomes less stable, hence harder to incorporate into an exoskeleton, as it will tend to dissolve.

With the exception of the molluscs, whose shells often comprise both forms, most lineages use just one form of the mineral. The form used appears to reflect the seawater chemistry – thus which form was more easily precipitated – at the time that the lineage first evolved a calcified skeleton, and does not change thereafter. However, the relative abundance of calcite- and aragonite-using lineages does not reflect subsequent seawater chemistry – the magnesium/calcium ratio of the oceans appears to have a negligible impact on organisms' success, which is instead controlled mainly by how well they recover from mass extinctions. A recently discovered modern gastropod Chrysomallon squamiferum that lives near deep-sea hydrothermal vents illustrates the influence of both ancient and modern local chemical environments: its shell is made of aragonite, which is found in some of the earliest fossil mollusks; but it also has armor plates on the sides of its foot, and these are mineralized with the iron sulfides pyrite and greigite, which had never previously been found in any metazoan but whose ingredients are emitted in large quantities by the vents.

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