Badfish

I know there are different theories on evolution, evolution within species and total evolution (and maybe others).

Do most of the evolutionists here at iidb believe:

1. Humans evolved from one celled organisms, crawled out of the sea, grew legs, and went through all phases of species to become man.

2. We all started as one celled organisms, and environment dictated our species, molecular structure and thus guided our evolutionary path to being human.

3. Different one celled organisms evolved into different and unique species, because of differing molecular structure.

I just want to find out what the majority of evolutionists here believe, if I missed the correct path of evolution please correct me.

I want to know what is the unanimous belief on the WAY we evolved, I take it there is a majority here, and all I am asking is for basic beliefs, choose 1,2, or 3, or your own basic belief if I missed it.

No need for molecular discussion, just the basics please.

scigirl

Hey there,

I would say 4) none of the above.

But I'm not exactly sure what the statement is to replace it.

Interesting question - I'll have to think about it.

I do think of evolution as creating more and more diversity and complexity from "simpler" organisms. It's more like a bush, not a ladder.

scigirl

KnightWhoSaysNi

Hi GTX. Good questions, but I only have time to deal with one of your points at the moment.

Actually, there's evidence suggesting that we got legs before we crawled out of the sea.

This is a quote from paleontologist, Neil Shubin, from the <a href="http://www.pbs.org/wgbh/evolution/library/04/3/l_043_41.html" target="_blank">PBS Evolution</a> series regarding his research in early tetrapod fossils:

[ July 24, 2002: Message edited by: Nightshade ]</p>

Hallucigenia

Can't speak for "most of the evolutionists here at iidb", but for myself: no. I believe, based on the evidence, that one-celled organisms were the ancestors of all other life on earth. However, it is not correct to say that said one-celled organisms "became" man, nor is the particular pathway you propose (which is, as it happens, remarkably Lamarckian). The path from "one-celled organism" to "man" is very heavily branched.

Quote:

2. We all started as one celled organisms, and environment dictated our species, molecular structure and thus guided our evolutionary path to being human.

Again, Lamarckian. We did not start as "infusorians", which then struggled to climb the Ladder of Perfection, in order to become Man.
Even aside from that, our particular path was determined by a variety of factors, including environment (which includes the effects of organisms on said environment), genetic structure, previous history of our ancestors, etc.

Quote:

3. Different one celled organisms evolved into different and unique species, because of differing molecular structure.

Molecular structure played a part, but other factors such as mutation rates/modes, selective pressures from the environment, etc., all served to shape organisms into their present forms. Including us.

[Fixed coding]

[ July 24, 2002: Message edited by: Hallucigenia ]</p>

Undercurrent

I think that the basic beliefs of an "evolutionist" would be:

1) Species are capable of changing over the time frame of several generations as a result of their environment, both morphologically and biochemically.

2) Such change is capable of splitting a species into two or more species over time.

3) The mechanism through which this change occurs is that proposed by Darwin (although I suppose Lamarkian evolutionists wouldn't hold this one.)

There are also some additional statements that, while they don't follow from the previous three, tend to be held by people who hold the previous three.

4) The age of the earth is on the order of a few billion years.

5) All life on earth is descended from members one or a few species that existed on the order of a billion to a few billion years ago. This/these ancestor species was/were not very complex compared to the most complex organisms alive today.

6) Humans are not fundamentally different from other animals. That is, our differences are ones of extent, not of kind.

7) The ancestry of humans looks roughly like:

single-celled organisms --&gt; multi-celled invertabrates --&gt; fish --&gt; primitive amphibians --&gt; primitive reptiles --&gt; mammals (humans included)

Are there any objections to these statements?

m.

scigirl

Michael,

You can check out this web site to see the current thinking about the "tree of life":

<a href="http://tolweb.org/tree/phylogeny.html" target="_blank">http://tolweb.org/tree/phylogeny.html</a>

scigirl

Starboy

Greetings GTX,

Here are my opinions on the subject, such as they are:

1. All life on earth evolved from one or more single celled organisms, mankind included, through a process that included mutations and natural selection. If that is evolution, then so be it.

2. The exact path of mutations and selections that produced mankind is unknown. I suspect it is more complicated then anyone has yet imagined, and it could very well remain unknown forever.

3. I don’t see myself as an evolutionist as such, but as a scientist. Evolution as it currently exists is just the most successful theory to date for explaining the variety and complexity of life as it is today and as is seen in the fossil record. I do feel that there are many people that are hung up on the word evolution. I can see how it may seem confusing to some, since it has been referred to as evolution ever since Darwin, but has changed greatly since his day on many of the details. From a public relations point of view, I think it would be of great benefit to biology if biologists would call the next iteration by some other name so that the public could more easily understand that it is a dynamic and growing field of study.

4. The details of the tree of life are changing constantly as more scientific knowledge comes to light. Since I am not a biologist I am not all that interested in specific details, what impresses me more is how well it fits what is observed.

5. It is not so much as I believe in evolution but that I have more confidence in the products of science than I have in any other source of human knowledge on the planet, past or present.

That’s my story and I’m sticking to it!

Starboy

Oh, almost forgot, and that evolution in as much as it is a scientific theory is part of the MOST SUCCESSFUL HUMAN ENDEVOUR FOR UNDERSTANDING OUR SURROUNDINGS IN THE HISTORY OF MANKIND.

[ July 24, 2002: Message edited by: Starboy ]</p>

Jack the Bodiless

Yes, subject to the major caveats already expressed in this thread.
No, because we didn't start as one-celled organisms. We started as self-replicating molecules.
No, one-celled organisms with initially identical molecular structures can evolve into many unique species, due to differences in environmental selection pressures and later random mutations.

Stephen T-B

Sounds fawning, but I wanted GTX not to have missed Starboy's clarification:
"I don’t see myself as an evolutionist as such, but as a scientist. Evolution as it currently exists is just the most successful theory to date for explaining the variety and complexity of life as it is today and as is seen in the fossil record."
Creationists do have this tendency to put "evolution" into the same sack as Genesis.
It's just not in there. GTX.

Kevin Dorner

Beliefs? No, I don't "believe" in evolution.

Instead, I accept it based on the overwhelming and confluent evidence from many scientific disciplines, ie: paleontology, anthropology, zoology, and genetics.

It's a common canard to equate its acceptance with a religious belief because this belies the evidence for it and makes it sound like an unprovable assertion, rather than one of the most well-supported theories science has ever developed.

Neither is evolution (for most people) an "obvious" idea. Life is exceedingly complex, and it certainly looks designed in some ways (such as how aquatic animals have hydrodynamic shapes) but conversely this is not evidence: the earth being roughly spherical (instead of flat) or moving through space is not an "obvious" idea either.

[ July 25, 2002: Message edited by: Kevin Dorner ]</p>