Evolve my knowledge - make me believe!, page 2

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reply posted on 10-4-2008 @ 01:05 AM by Neiby

Good grief...one more and then I'm going to bed! I swear! I just ran across this fantastic site. It's the Evolution site for Berkeley.edu and it looks wonderful. You might want to take a look at it if you want to get more in-depth with this stuff. It appears to have a wide range of information at varying levels of complexity.

Berkeley Evolution Site

reply posted on 10-4-2008 @ 03:07 AM by C.C.Benjamin

Originally posted by MatrixProphet
No you cannot prove that there is a Creator, nor can it be proved that there isn't one. This is where logic can come in.

Science has not been able to explain how the birds wing nor the human eye came about through evolution. It is one of the arguments that is plaguing the scientific community. The more evolved the scientific community becomes the more unanswered their questions.

There is a definite separation amongst the scientists that is going on. It would be no surprise that we would not agree. But I do find it interesting that there are some die hard former evolutionists that are now saying that evolution is no longer feasible. Out of curiosity, have you kept up on this?

Actually, there is suggested evidence.

This was something I learned years ago, probably during A-level Biology.

There is a species of worm that has light-sensitive cells at one end. There is also a species of worm that has these light-sensitive cells arranged in a concave dip.
This then is succeeded by a type of worm that has a jelly-like oval over a concave collection of light-sensitive cells - this is the first eye.

It basically scales up from there, but there is definately evidence to suggest that eyes did evolve, no matter how complex they are.

reply posted on 10-4-2008 @ 10:29 AM by TheRedneck

Well, I must say, perhaps I should read my own signature more.

I have indeed gotten exactly what I was asking for. Neiby, those links were impressive; I scanned them over and they really don't seem too advanced. I caution you, beware of stereotypes; this old redneck does understand science (beyond 1001 uses of duct tape).

I mentioned in an earlier post in this thread that this particular question is only one of many problems that I see with evolution. It is also representative of the vast majority of the concerns I have, and therefore the answers I have gotten are somewhat applicable to all my questions.

As to the issue of evolution covering life origins, I can only tell you that, while it may well be that this is now considered separate from evolution, it was not always so. It wouldn't be the first time I have found scientific thinking to have moved so far from what I was taught as to actually start an argument. In my mind, evolution will always include the 'primeval soup' theory, since it did when I first learned it, but I will try to take this change into account in future debates. Science does advance, as is proper, and it's difficult to keep up with all the advancements. That's why most scientists specialize.

Walking Fox, I will say this again: On this subject, you have made an excellent opponent and taught me much. On the subject of religion, I am actually a bit loath to reply to you, because your posts are so far removed from reality. But, if you insist, I can do so.

I really don't want this thread to die. So, at the risk of sending it completely off-topic, I will pose a few more questions:

1. The reproductive system in heterosexual animals is one of the most complex systems in biology (IMHO anyway). It operates very differently from asexual mitosis. Is there an intermediate link between these two, or how could an organism that used mitosis as reproduction have evolved into two different sexes?

2. Assuming the lack of any intelligent design, variations which drive evolution must be random and without thought as to the mutation being undergone by that being evolved. It would stand to reason that more can be wrong with any organised system than could be right with it. For instance, there are many many mutations of the eyeball that would render it useless, yet few would improve its efficiency. so there should be a great many failed mutations for every successful one. Should we not see much evidence of these failed mutations, or has that evidence simply escaped me?

TheRedneck

reply posted on 11-4-2008 @ 06:51 AM by shihulud

Originally posted by TheRedneck

As to the issue of evolution covering life origins, I can only tell you that, while it may well be that this is now considered separate from evolution, it was not always so. It wouldn't be the first time I have found scientific thinking to have moved so far from what I was taught as to actually start an argument. In my mind, evolution will always include the 'primeval soup' theory, since it did when I first learned it, but I will try to take this change into account in future debates. Science does advance, as is proper, and it's difficult to keep up with all the advancements. That's why most scientists specialize.

There is the possibility that life started (or was helped along) in ice at very low temperatures due to the higher concentrations of the chemicals needed being excluded from the ice and being gathered in ice pockets - see link in my last post for full details.

2. Assuming the lack of any intelligent design, variations which drive evolution must be random and without thought as to the mutation being undergone by that being evolved. It would stand to reason that more can be wrong with any organised system than could be right with it. For instance, there are many many mutations of the eyeball that would render it useless, yet few would improve its efficiency. so there should be a great many failed mutations for every successful one. Should we not see much evidence of these failed mutations, or has that evidence simply escaped me?

TheRedneck

I would assume most of these failed mutations would have either been aborted (depending on the genetics) or been eaten by other animals due to lack of survivability that the failed mutation gives. On the other hand look at all the people with glasses and other eye deficiencies - some of them could be failed mutations.

G

reply posted on 16-4-2008 @ 05:03 AM by Astyanax

Can I play too?

Hi, TheRedneck. First I have to tell you flat out that you are all wrong, ya got it all backwards, you dunno what you're talking about yadda yadda yadda...

...TheWalkingFox is not stupid. She's one of the smartest tacks on this board. Even if she is a baby-eating Socialist.

On topic now. I'd like to try my hand at answering some of your OP questions.

One mutation at a time

The idea of multiple genetic mutations occurring simultaneously to advance a species is a bit too fantastic for me.

You're quite right, and no evolutionary biologist would suggest such a thing.

The point is, there's no need for multiple simultaneous mutations to occur. One mutation at a time will do. In fact, any mutation that needs other simultaneous mutations to make it work is ipso facto a deleterious mutation, and will be selected out of the gene pool.

So how do complex structures like the eye and complex adaptations like flight evolve? What good is part of an eye, or the beginnings of a wing?

As it turns out, quite a lot of good. Complex animal eyes have evolved from less complex ones, which evolved from clusters of light-sensitive cells. This Wikipedia page explains the process in detail. It turns out that any sensitivity to light can offer, under the right circumstances, a selective advantage. Greater sensitivity increases the advantage, as does greater image definition, and thus the eye evolves, little by little.

As a matter of fact, eyes have evolved separately, from scratch, many times over on this planet. I know you said you didn't want quotes, but I can't resist this very illustrative (pardon the pun) one from Richard Dawkins:

It seems that life, at least as we know it on this planet, is almost indecently eager to evolve eyes. We can confidently predict that a statistical sample of reruns (of evolutionary life on Earth) would culminate in eyes. And not just eyes, but compound eyes like those of an insect, a prawn, or a trilobite, and camera eyes like ours or a squid's, with color vision and mechanisms for fine-tuning the focus and the aperture. Also very probably parabolic reflector eyes like those of a limpet, and pinhole eyes like those of Nautilus, the latter-day ammonite-like mollusc in its floating coiled shell... There are only so many ways to make an eye, and life as we know it may well have found them all.

- The Ancestor's Tale

As for adaptations like flight, the same process holds. A dinosaur species has feathers for insulation. An individual is born carrying a mutant gene that codes for longer-than-usual feathers on the forelimbs. Windmilling its forelimbs lets it climb hills faster. This gives it an advantage in escaping floods, predators or whatever and so the mutation prospers. Longer forelimbs, hollow bones and all the rest evolve in time, as the species goes from landbound to hopping, to gliding and finally achieves true flight.

Or imagine an arboreal creature that spends its life leaping from limb to limb. Successive mutations shape its body to achieve more and more lift, like a flying squirrel or gliding loris. Further mutations permit control of the lifting surfaces so it can direct its glide more effectively. Eventually, this process, too, can result in the evolution of flight. No designer required.

Another thing you must remember is that mutations occur in DNA; it is genes that mutate. And every gene in your body codes for a whole variety of characteristics. So a mutation involving only one gene could cause a whole raft of changes in the bodies and behaviour of the mutant's offspring.

From one cell to many

Given that an amoeba does not maintain any cohesion with other amoebas, and the obvious idea that two independent such animals stuck together through cellular cohesion would be less likely to survive, how could this transition have happened?

First, let's kill the amoeba, okay? Amoebae are pretty advanced creatures. Let's go to the real primitives, bacteria. Bacteria do in fact live in colonies, and this way of living offers them numerous advantages. In fact, bacteria colonies are highly structured and organized. Please allow me another quote:

Recent studies suggest that... bacterial cells can actively seek out small chambers or cavities and assemble there, engaging in quorum sensing behavior.... Within chambers of distinct shapes and sizes allowing continuous cell escape, bacterial colonies can gradually self-organize... The ultimate highly organized steady state is conducive to a more-organized escape of cells from the chambers and increased access of nutrients into and evacuation of waste out of the colonies... The cells might be optimized to maximize self-organization while minimizing the potential for stampede-like exit blockage. The self-organization described here may be crucial for the early stage of the organization of high-density bacterial colonies... It suggests that this phenomenon can play a critical role in bacterial biofilm initiation and development of other complex multicellular bacterial super-structures, including those implicated in infectious diseases.

- Self-Organization in High-Density Bacterial Colonies: Efficient Crowd Control

This 2007 paper has been blowing minds all over the place, by the way. It suggests that bacteria communicate using chemical signals; and that this allows bacterial colonies to manifest a kind of intelligence that the bacteria themselves don't have, just as animals have intelligence their individual cells don't possess. In passing, it also explains how easily, and to what advantage, single-celled biota form multicellular arrangements.

Also, don't forget the weird form of symbiosis in which one single-celled organism ingests another, not for its food value, but to make use of its functionality. Thus mitochondria, the cells-within-cells that provide the energy for all animal cells to function. Another possible path from unicellularity to multicellularity.

In the Beginning

Life, what's that? When did something nonliving first turn into something living, and just what does that mean? It is quite true that science has no solid, research-tested model for the origins of life. However, there is a widely accepted scenario, which goes something like this.

The location is probably critical, but we don't know what kind of location it was. Perhaps a warm, shallow Precambrian sea; perhaps a boggy tidal flat; perhaps some analogue of Darwin's famous 'warm pond'. Lots of simple organic molecules in suspension -- but this is still a very thin, watery soup. Some energy input -- lighting strike, cosmic ray, maybe just plain sunlight -- causes a few of these simple molecules to join up and form more complex ones. Most of them don't last long before disintegrating; a few do.

Repeat the process over time, in many places. Soon you'll have a lot of different kinds of molecules floating in the soup.

One of these molecules becomes capable of replicating itself. It does so by attracting other molecules to itself (simple chemical bonding) in a certain order set by its own physical structure, which forms a template on which the attracted molecules combine into a facsimile of the replicator. This is still the process by means of which DNA creates RNA and RNA creates proteins in the ribosome. Doubtless the earliest replicator used a very simplified form of it.

But not all the copies are perfect; copying errors set in. These are in turn replicated. Variation ensues.

The conditions for evolution by natural selection now exist. You have a selection of differently-shaped replicators floating in the soup, all using the ingredients of it to make copies of themselves. Some will be better at this than others. They will multiply faster. The ones who aren't so good at grabbing and making use of the available resources will not prosper, and many will be used as raw material by the ones that are. Evolution has begun.

From that point forward, natural selection does the rest.

Note that in this scenario, evolution and natural selection begin their work before anything worthy of the name of 'life' even appears on the scene -- they begin at the stage of single molecules. The fact that we don't know exactly how life originated does not throw into doubt either the fact of evolution or the theory of natural selection.

* * *

I'm not a biologist, but I'll be happy to answer anyone's questions on this to the limit of my knowledge, and I'm sure real biologists like Jazzerman and melatonin will be happy to step in to clarify things for you and put me right whenever the need arises.

reply posted on 16-4-2008 @ 05:04 AM by Astyanax

The Mystery of Sex

The reproductive system in heterosexual animals is one of the most complex systems in biology (IMHO anyway). It operates very differently from asexual mitosis. Is there an intermediate link between these two, or how could an organism that used mitosis as reproduction have evolved into two different sexes?

Rather than talking about meiosis and mitosis, which I think only serves to confuse the issue, let's talk about organisms. Parthenogenetic organisms reproduce as clones. Sexual reproducers mix their genetic material. The latter start with a disadvantage: all other things being equal, they can have only half as many offspring as parthenogenetics. So for sex to evolve, there has to be a corresponding advantage in mixing genes. The advantage seems to be keeping parasites at bay by providing genetic variation for natural selection to work on, allowing some individuals to develop immunity (until the next step in the evolution of the parasite, at least -- it's an arms race). The fact that the offspring of sexual mating have to be fertile as well provides a frame of constraint that prevents too much genetic drift from the mixing.

That answers the 'why' part. But when you ask how sex evolved, you're asking a question to which science has no answer. It is one of the great mysteries of biology. But this hardly calls evolution into question.

There should be a great many failed mutations for every successful one. Should we not see much evidence of these failed mutations, or has that evidence simply escaped me?

Mutations or mutants? There are plenty of failed mutations around -- DNA that doesn't code for anything. Of course, it may turn out -- seems to be turning out -- that 'junk DNA' isn't really junk at all, but that's another discussion for a different thread.

You also see lots of vestigial, useless bits and pieces in nature, not least in the human body. You might call these failed mutations.

But I think you mean failed mutants -- organisms that are at a selective disadvantage compared with their conspecifics as a result of a mutation. Well, obviously you don't see them around; being less fit, they fail to reproduce, and die out. Nature really is red in tooth and claw.

[edit on 16-4-2008 by Astyanax]

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