Quick question on evolution

[Seipai]

Ok, so a vertebrate fish will give birth to another vertebrate fish, and they'll always produce vertebrate fish. I suppose that non-vertebrate fish will always produce non-vertebrate fish. Yet, a non-vertebrate fish is supposed to have a common ancestor with a vertebrate fish? That's the part I don't understand.

I guess that I misunderstood this question.

So to make up my earlier accusation let me try to explain this for you:

The boneless forerunner of bony fish evolved from boneless chordata. The ability to generate bone was in all probability a simple mutation that started out with a small amount of protection that increased due to its positive effects. You might want to ask a biologist for more details.

What many creationists conveniently forget is that the atmosphere and also the dissolved materials in the seas changed as life evolved. Animals could not evolve to use and make calcium carbonate until there was a significant amount of dissolved oxygen in the water.

 

[biggles53]

Thanks for the good explanation, but I admit I'm still having trouble. (Although I was quite accomplished in getting my college degrees, I was never very good at biology.) I'd like to keep things as simple as possible.

Maybe I'm misunderstanding what you said, but it seems to me that you're saying that an offspring is the same type of being as its parent, but with a tiny change at its core. If you go on for millions (?) of generations these tiny changes will have resulted in an offspring eventually being a totally different type of being as the ancient ancestor. Is that right?

If I understand you right, then I guess you're saying that there once was a bacterium many millions (?) of generations ago, and because of the tiny changes, that bacterium's offspring eventually resulted in a human?

A single-celled life form...yes. And it's hard to comprehend isn't it...? But then, billions of years of time are hard to envisage too...

 

[biggles53]

I have gained some understanding that I didn't have before. And I haven't criticized anything. Where'd you get that from?

You're doing fine...

As long as you keep asking questions AND keep your mind open to the answers you receive, things will make sense more and more...

 

[loveofourlord]

it's not that fish will always produce fish and not become amphibians and such, it's that the descendants of a given species look just like their ancestors, but over large periods of time you notice a difference. Like if you were to look at the ancestor or modern rats and Leopards, and follow that line up to leopards, at no point in the line if you looked at all the mothers would any child look different from it's mother, or even every 30th or 100th maybe, but if you place just every 400th or 1000th animal the differences would become far more pronounced, you would clearly see the transition This is what is meant.

 

[dysert]

Has any scientist offered up any idea as to how many generations it took for the first single-celled organism to become "us"?

 

[Seipai]

Has any scientist offered up any idea as to how many generations it took for the first single-celled organism to become "us"?

No.

And there is a very good reason for that. Most of the generations would probably have occurred when life was still in the unicellular stage. Generations can be extremely short under the right conditions. There are so many variables that the error range could be larger than the actual number.

 

[loveofourlord]

Has any scientist offered up any idea as to how many generations it took for the first single-celled organism to become "us"?

Too many variables, different species have different rates, also could could be in a direct way very short, but in a long way a long time.

AKA it may only take 5000 generations to go from fish to amphibians, but it took 500k generations of fish before the mutations happened that took it on that path.

There are some interesting discoveries in extant species that might give help in discovering how multi cellular developed, some like g.spherica are large enough I think to allow for multiceullar without much trouble, others organisms have single cell and multi cells in their life cycles depending on their needs.

 

[[serious]]

Has any scientist offered up any idea as to how many generations it took for the first single-celled organism to become "us"?

We could probably put some caps on it. For example, if we take a 20 year generation time for humans, and the time life has been kicking around for (3.5 billion years) we would get 175 million generations. Now, most life has a shorter generation time that that, so let's treat that as a minimum number of generations that have occurred. It isn't uncommon for bacteria to have generation cycles of an hour or less (some as fast as 15 minutes as I recall). If we assume a generation length of 1 hour we would get 30 trillion generations.

For our first approximation, we can say that it took more than 175,000,000 generations, but less than 30,000,000,000,000

 

[[serious]]

Thanks for the good explanation, but I admit I'm still having trouble. (Although I was quite accomplished in getting my college degrees, I was never very good at biology.) I'd like to keep things as simple as possible.

Maybe I'm misunderstanding what you said, but it seems to me that you're saying that an offspring is the same type of being as its parent, but with a tiny change at its core. If you go on for millions (?) of generations these tiny changes will have resulted in an offspring eventually being a totally different type of being as the ancient ancestor. Is that right?

If I understand you right, then I guess you're saying that there once was a bacterium many millions (?) of generations ago, and because of the tiny changes, that bacterium's offspring eventually resulted in a human?

Hundreds of millions of generations, if not billions or even trillions of generations, but yeah. Just like eating an elephant, you do it one step at a time. Looking at the big picture, it appears to be a daunting task. If you zoom in, you realize that it's made up of lots of pretty manageable tasks.

For example, going from single celled life to multicellular life. Hard to imagine, but lets break it down:
1. Would it be hard to imagine single celled life forming colonies or films on some surface? Sure! swimming away vs latching on is a pretty reasonable thing to evolve. We can picture that. ok, so now we've got a group of cells.
2. Could they all want to do something at the same time? Maybe let go of their surface at the same time? Sure, there are reasons for that. So maybe there is some chemical change that occurs when one lets go. Some chemical gets released as part of that process. We could imagine the sensing of that chemical triggering the next to release, releasing more chemical, triggering more, etc. We now have a mechanism for group action
3. Could we get from group action to some degree of differentiated action? Maybe some interplay between those released signals and immediate environment. Something like,
IF signal X grab on to cells near you
IF touching rock THEN release something to break down rock for nutrients.
ELSE wave cilia around and catch stuff in the water for energy
ELSE swim around
So now we've got a basic level of differentiated function. We've gotten to a simple kind of multicellular life.

 

[Gracchus]

I asked my question, not wanting to debate, but rather to try to understand. So please take this in the spirit intended. It seems to me that someone growing up is not a reasonable analogy to evolution. The person neither gains nor loses DNA in the growing process; there is no reproduction involved;...

(There is reproduction involved, although it is the asexual reproduction of cells.)

... and not only does the person remain a "person" they actually remain *the same* person.

(They eat food they metabolize they excrete, it is a convenient fiction that they are the "same person".)

Hopefully there's a better explanation (that I can still understand). Thanks.

A person starts as a single cell, a fertilized egg. That egg divides and eventually differentiates into germ layers, ectoderm, endoderm and mesoderm, and then the cells differentiate further into tissues and organs. This differentiation occurs because genes are turned on and off by the chemical environment of the cells. Even that first cell had a chemical gradient so that the cells that developed from it differed chemically and so developed into different types of cells. It's true that all of those cells have the same DNA but because of different chemical environments they develop differently. The adult human is not really the "same person" as the fertilized egg, anymore than the sap of a rubber tree is a tire.
In multicellular organisms sexual reproduction gives rise to greater genetic variability. The total physical environment provides feedback, and various feedback systems drive the organisms to specialize and become different.
(See for instance, "The Beak of the Finch".)
Now I could, and others could, try to explain in metaphors how it works but you would dismiss the metaphor because it is a metaphor. So, if you want to understand how evolution works you'll actually have to inform yourself about genetics, molecular biology, developmental biology, and ecology.
If it could be taught in a few hundred words, there would be no reason for years of college courses to become proficient.
As it is, you can learn more about biology in a few hours than was known by the wisest men for thousands of years.
I would refer you to a book like Ernst Mayer's "What Evolution Is".

 

[Loudmouth]

The common ancestor thing is a theory about what may have happened in the far distant past. This aspect of evolution is a theory composed of a thousand fictional events that may have occurred.

It is a testable theory that makes predictions about what we should and shouldn't see when we compare genomes, fossils, and living species. As it turns out, those predictions are accurate, and creationists have no explanation why a supposedly false theory is able to make so many accurate predictions.

What you are really rejecting is the scientific method because you don't want people to follow the evidence. Instead, you want them to believe in a religious dogma that runs counter to the evidence. I can certainly understand why science is such a problem for you.

 

[Loudmouth]

Has any scientist offered up any idea as to how many generations it took for the first single-celled organism to become "us"?

It takes 9 months.

 

[Loudmouth]

Maybe I'm misunderstanding what you said, but it seems to me that you're saying that an offspring is the same type of being as its parent, but with a tiny change at its core. If you go on for millions (?) of generations these tiny changes will have resulted in an offspring eventually being a totally different type of being as the ancient ancestor. Is that right?

It will not be totally different. It will still have some features found in its ancestors. We still share features with single celled organisms. We are not totally different from our single celled ancestors.

The phrase that Darwin used was "descent with modification".

 

[juvenissun]

I identify myself with theistic evolution simply because the alternative normally assumes atheism. But I don't believe TE is any different in the way things work.

The Reformed tradition assumes that God almost always acts through "secondary causes." That is, he has a plan for everything that happens, but that plan involves normal natural processes and human choices. God doesn't have to intervene all the time. God's personal interaction normally involves people, where it takes the form of the Holy Spirit working with his followers.

The problem with God intervening all the time is that it would result in a chaotic universe, where people's choices didn't matter, because God would determine the results independent of normal processes. Christians believe in creation, not pantheism. That is, God created a universe that has an existence of its own, operating lawfully. For most of Christian history, this lawfulness was taken to be a reflection of God's own character.

If you really see the insight of evolutional process, you will find that without miracles, evolution simply won't take place. This is a scientific argument, not a theological argument.

If you do not see that, of course, you may even say that evolution is a fact. Many people do think that they ARE animals.

 

[Loudmouth]

If you really see the insight of evolutional process, you will find that without miracles, evolution simply won't take place.

Mutations and selection have been observed. No need for miracles.

 

[Dizredux]

Many people do think that they ARE animals.

And some even think they are professors of Geology.....(grin)

Dizredux

 

[PsychoSarah]

If you really see the insight of evolutional process, you will find that without miracles, evolution simply won't take place. This is a scientific argument, not a theological argument.

If you do not see that, of course, you may even say that evolution is a fact. Many people do think that they ARE animals.

Chimpanzees have frontal lobes, temporal lobes, occipital lobes, etc. just like humans do. Except for our well developed frontal lobes, a human brain isn't really notably different than that of other animals.

 

[[serious]]

If you really see the insight of evolutional process, you will find that without miracles, evolution simply won't take place. This is a scientific argument, not a theological argument.

If you do not see that, of course, you may even say that evolution is a fact. Many people do think that they ARE animals.

How is that different than saying humans are mammals or vertebrates?

 

[keith99]

Animals don't age?

Guess not, kittens do not grow into cats and puppies do not grow into dogs.

Oh wait, they do. And just like humans one cannot point to the specific moment a kitten becomes a cat or a puppy a dog!

 

[dysert]

If you really see the insight of evolutional process, you will find that without miracles, evolution simply won't take place. This is a scientific argument, not a theological argument.

If you do not see that, of course, you may even say that evolution is a fact. Many people do think that they ARE animals.

What miracles are you talking about that are necessary for evolution to occur?