| From: andrew | 31/05/99
11:45:20 |
| Subject: evolution |
post id:
14789 |
| Tell me were my logic is wrong.
how did the first little critters formed know to reproduce. I heard
somewhere that they would be formed say from a lightening strike and
ammeno acids. They would therefore be created and die before figuring out they need to reproduce. Unless these cells somehow automatically multiplied and mutated over the years and eventually turned into us. | |
| From: Super Elmo | 31/05/99
12:36:44 |
| Subject: re: evolution |
post id:
14816 |
| Evolution...Well, the single
celled organisms came from other parts of space, and traveled here on
metorites and comments, being deposited onto earth when a metorite smased
into the earth or a passing comet's dust settling on Earth, and lost of em
did many moons ago.We evoloved from these single celled organisms that
lived on Earth all those moons ago. These single celled organisms, lived
around volcanic vents in the earths crust under the ocean, there was no
light, so all heat for these organisms camre from these vents. These
organisms re-produced by duplicating it's DNA, within itself (just as
other single celled organisms), and the splitting into 2. From there,
these cells evolved into multiple celled organisms, which requred 2
organisms to breed, from there they became aquatic animals, which can move
around the sea, abet small, and remove oxygen from the ocean, from there
they evolved lungs, and were able to go in the sea, as well as land, they
then lost their gills, and their fins evolved into feet, from there they
became humans and began to reproduce. Hope this helps out. | |
| From: Mark Dawson | 31/05/99
13:16:46 |
| Subject: re: evolution |
post id:
14827 |
| Super Elmo, there is no need for
the organisms to arrive here on comets. They could have evolved here on
earth, all seeding from outer space does is move the location of
development of the earliest cells. I suspect that the earliest "life" were
proteins called "Prions". These are not alive in the usually sense as they
contain neither DNA or RNA. They can however reproduce by converting other
proteins into prions. Prions are the cause of mad cow disease and kuru. As
both proteins and DNA are made up amino acids, there could be some link
there. | |
| From: Terry Frankcombe | 31/05/99
14:15:53 |
| Subject: re: evolution |
post id:
14850 |
| Woohoo! Love these el\volution
debates! Evolution is a freaky thing. I think the best answer to your question is just that it just happened. Evolution is driven by variation, which arrises partly from sexual reproduction (as creationists will tell you) and partly from genetic mutation (as biologists will tell you. That's the bit a lot of creationists ignore or don't believe). Ultimately it all came from genetic mutation, but I won't go into that. Basically, things survive if they survive. Silly though that may sound, it makes sense if you think about it. The first organisms would probably have reproduced asexually (I just stuck the probably in there to be safe!) However, at some point some funny little mutation meant that a particular organism grabbed some genetic material from its nearest neighbour, and became sexual in the first act of sex on the planet! Because this additional mixing of genetic material allowed it to change more rapidly as a species, this whole sexual thing became quite popular, because these organisms could, as a 'species', adapt and survive as things changed around them and everyone else died. | |
| From: Mark Campbell | 1/06/99
13:22:41 |
| Subject: re: evolution |
post id:
15126 |
| DISCLAIMER: This is a touchy
subject so I want to make it clear from the get-go that I am not
attempting to advocate nor criticise Evolution or Creation. I actually
believe that neither theory will ever be confirmed or disproved, there
just isn't enough information to prove it either way. This means that no
matter which theory is true, it comes down to a matter of faith. Which
theory do you believe in? I am not attempting to prove or disprove either
theory here, I am simply pointing out one flaw in one theory. There are
many flaws in both theories, however, just because I am not discussing
them, doesn't mean I don't acknowledge them. Save your flames. One of the biggest problems I have always had with the theory of evolution (apart from the fact that it is presented, mainly to school kids, as fact rather than a theory) is the fact that it does not explain (to my satisfaction) how there came to be a living thing from a non living thing. It pretty much explains all of the rest adequately but breaks down at that point. I have heard the hypothesis of the lightning strike creating amino acids but aminos aren't alive. How did a living organism grow out of amino acids? Also, if the conditions for creating life were as simple and common as a pool of sludge and a lightning bolt, wouldn't we have seen it happen again and again and, in fact, still observe it happening to this day (ie. new micro organisms being formed from scratch). So, I guess there are 3 biggies to ask... 1) At what point can something be said to be alive? 2) At what point did organisms go from not alive to alive and what was the process? 3) Why is the process not continuing to this day? Although I am fairly knowledgeable about evolutionary processes, I am by no means an expert so it is entirely possible that I am wrong about evolution not being able to explain how life began. However, I am pretty sure that I would have heard of it was so. Ironically, although creationism doesn't really explain the transition of a non living thing into a living thing (just that God did it), it does at least account for it. Anyway, like I said, I am not trying to advocate one theory over the other. My view is, give people all the facts and let them make up their own minds, but give them ALL the facts. | |
| From: Terry Frankcombe | 2/06/99
7:13:45 |
| Subject: re: evolution |
post id:
15361 |
| 1) At what
point can something be said to be alive? No idea. Sue? 2) At what point did organisms go from not alive to alive and what was the process? Don't be too hard on the possibilities of 'life' spontaneously coming into being. One of the pre-reqs for life as we know it is a cell in which to house the required chemistry. Cells can certainly form. I have watched relatively common surfactants spontaneously self-assemble into closed circular membrane structures roughly cell-sized. 3) Why is the process not continuing to this day? Why do you say that it isn't? How do you know that it isn't continuously happening? It only has to happen once for life on this planet to get a kick along. What if the probabilities for such an event were such that it occured on average once every hunderd thousand years? Or even ten thousand? The process could be alive and well, but we would have no idea. Then again, even if somewhere in the world a bacterial life-form spontaneously came into being roughly once a year. Would we (as a race) notice? It would only need a single cell. Would you notice if a single cell sprung to life in your garden pond, and died a few days later? | |
| From: Mark Campbell | 2/06/99
9:21:05 |
| Subject: re: evolution |
post id:
15368 |
| Just a few comments in reply to
your points Terry... 1) Hmmm, I'd be very interested to see if anyone knows the answer to this one. Perhaps everyone has a different definition. Sue seems to know all things biological...Where are you Sue? I'd love to hear what you think about all this... 2) This sort of ties in with number 1...Terry, where but where did you get that info from? I'm not disputing it, I just figured that if you know one of the prerequisites for life, you may know others (or at least know where to find them). I would imagine that there are quite a few prerequisites to be satisfied before you could say something is alive. For example, IMHO it would have to be able to reproduce (by some method or another), it would have to grow and/or develop in some way (maybe?) and so it would have to use energy of some sort (or perhaps, more accurately, convert energy into matter or other types of energy), as you said, it would have to be capable of forming a cell(s). Probably lots more... Pardon my ignorence, but what's a "surfactants"? 3) Aren't there people out looking for this sort of thing? I would have thought that there would be thousands of people wading about in ponds all over the world, microscopes in hand, looking for new types of life. Not only would the discovery of a new type of life look good on a resume but it would have to go a long way to proving evolution wouldn't it? Fairly big incentive. Is there any way of dating how old a living thing is? I don't mean the individual organism's age but how many generations or years or whatever the species has been around? If this could be done, I'm sure we would have a useful tool for proving/disproving evolution/creation (Well, perhaps not creation because creationists can get around any question by saying "God did it". Can't argue with that I'm afraid). Thanks for your comments Terry, I am finding the topic of what consistutes life terribly interesting. I look forward to hearing what you (and everyone else, of course...) has to say about my last few comments... | |
| From: Terry Frankcombe | 2/06/99
9:36:11 |
| Subject: re: evolution |
post id:
15371 |
| OK. Surfactants are 'surface
active' molecules, or molecules with a polar (charged) bit at one end
while the rest of it is basically oil-like (commonly refered to as the
polar head and hydrocarbon tail). When I say one of the pre-reqs for life, I mean an aspect of life as we know it today. Current biochemistry would not work if the reactants were allowed to float away. Though I'm guessing, I'm not sure that the ability to reproduce would be a defining feature of life. We need a better definition. I can't remember which particular molecule was self-assembling. For more details get hold of Dr Ben Selinger at the Chemistry department at ANU. I'd maintain that the spontaneous creation of life would be such a rare event that there are simply not enough people on this planet to have a good chance of observing life in any particular period of time, even if we were all looking. | |
| From: James Richmond (Avatar) | 2/06/99
12:19:04 |
| Subject: re: evolution |
post id:
15423 |
| I'll give this one a go... First
the big questions: 1) At what point can something be said to be alive? I don't think there is a definite answer to this. Everyone has an intuitive idea of what "life" means, and can usually say whether any given thing is alive or not. But it is very hard to pin down a list of criteria for life. We can list some features of life, such as the ability of an organism to reproduce, react to its environment, maintain or build its structure, move independently and so on. However, organisms exist which lack one or more of the things on our list, but which we'd still argue are alive. If I was forced to choose a single criterion for life, I'd probably opt for the ability of an organism to manipulate its environment to its advantage. I also think that if there is doubt as to whether something is alive or not, it is best to assume that it isn't. 2) At what point did organisms go from not alive to alive and what was the process? Since it is so hard to set criteria for life, the boundary between "alive" and "not alive" is necessarily hazy. I'd say that things went from not alive to alive when they started to use their environment to their advantage, for example, to reproduce. The process which allowed organisms to take the step to life is not clear. Personally, I favour spontaneous generation from organic (in the chemical sense) molecules. Basic chemistry has shown us that, with the right raw materials (simple molecules) and an energy source (like electricity in the primordial atmosphere or heat from geothermal sources), molecules such as amino acids form spontaneously. The amino acids could conceivably form more complex molecules, which at some stage started to act as if they were alive (and hence became alive, by definition). 3) Why is the process not continuing to this day? This is easier to explain. Conditions today are much different from what they were when life arose for the first time. The major difference the Earth is covered with life today, whereas there was none on the primordial planet! Each form of life on Earth today has to compete with other organisms for survival. This competition, together with the evolutionary process, means that today, even the simplest living things are reasonably complicated. If they weren't, they would be eaten, or couldn't get what they need to survive. When life first formed, on the other hand, the competition was less fierce, or even non-existant. Today, if a very simple lifeform arose spontaneously (which may happen quite often), it would almost immediately be eaten or otherwise used by one of today's complex organisms. This is why we don't see multiple parallel evolutionary paths occurring simultaneously. Only the fittest (best adapted to the environment at the time) survive. Today's organisms are much "fitter" than the first forms of life, but the first forms of life did not have to compete with today's organisms. ------ A few miscellaneous comments on previous posts: DISCLAIMER: This is a touchy subject so I want to make it clear from the get-go that I am not attempting to advocate nor criticise Evolution or Creation. I actually believe that neither theory will ever be confirmed or disproved, there just isn't enough information to prove it either way. This means that no matter which theory is true, it comes down to a matter of faith. No scientific theory is ever "proved" conclusively, except in mathematics. What we do is to run with the theory that best explains all the available evidence. In this particular area, evolution is streaks ahead of creationism. It is not a matter of faith. It's a matter of evidence. In any case, creationism is not even a true scientific theory. A scientific theory must, in principle, be falsifiable. Evolution is. For example, if we ever find a single organism which is shown (via DNA, for example) to have no relationship to any other type of life on the planet, we will be forced to conclude either that it evolved elsewhere (which would have Earth-shaking consequences) or that evolution is wrong. Can anyone point out a possible observation which would falsify creationism? One of the biggest problems I have always had with the theory of evolution (apart from the fact that it is presented, mainly to school kids, as fact rather than a theory) is the fact that it does not explain (to my satisfaction) how there came to be a living thing from a non living thing. It pretty much explains all of the rest adequately but breaks down at that point. The theory of evolution makes no attempt to explain how life arose initially. It describes what happens when living things have to compete for survival, which presupposes that there are living things in the first place. The origin of life is a completely sepa | |
| From: James Richmond (Avatar) | 2/06/99
12:20:11 |
| Subject: re: evolution |
post id:
15424 |
| [continued...] The origin of life is a completely separate issue. But once you've got the first living thing, you're off and running with evolution. Creationism, of course, supplies a neat answer to how life arose - God did it. Some people may find this more satisfying than not knowing the answer (which is the current scientific position). Perhaps God did do it. But even if this is true, I, for one, would like a few more details filled in. And it is important to remember once again that "God did it" is not a scientific statement, since the statement is not falsifiable. Is there any way of dating how old a living thing is? I don't mean the individual organism's age but how many generations or years or whatever the species has been around? If this could be done, I'm sure we would have a useful tool for proving/disproving evolution/creation. We can analyse the DNA of organisms to see how it has changed over time. This is a bit limited, since 90% of species which have lived on Earth are no longer around today, so their DNA is not available. To chart evolution (a process called cladistics) we have to make do with the organisms alive today, along with the physical characteristics visible in the fossil record. Even so, impressive progress has been made in this field. It is possible to estimate roughly how long it would take for various changes to accumulate in the DNA from one species to another. Such analyses put the age of the Earth as much older than the 6000 or so years the creationists are so keen on. Of course, God might be trying to trick us... JR | |
| From: Mark Campbell | 2/06/99
13:55:27 |
| Subject: re: evolution |
post id:
15470 |
| Thanks James. Very informative
and thorough. Interesting stuff this, innit? Well, I think so. So, If evolution doesn't attempt to explain the origins of life, what does? Has anyone attempted to go beyond "God did it"? ;-) James did mention the creation of aminos from a certain "soup" of chemicals and electricity but as I'm sure you would agree, amino acids aren't alive (by most peoples definitions). He then went on to say that he could see how the acids could group and become more complex until they became alive. However, I'm having trouble picturing the actual point of..dead, dead, dead, dead, oops, alive now. (I probably should be saying "not alive" rather than "dead" because someone will pick me up on it for sure but...Oh well, you know what I mean. "Dead" is easier to type than "not alive".) Sorry if I'm appearing to be difficult, it is not my intention. It's just that I'm really interested in finding out if anyone has ever postulated a theory on how an organism actually became alive and what that theory is. If the answer is no-one ever has then I'll be disappointed, but my curiosity will be sated (for now at least). I agree that the line between dead and alive is blurry but there still must be a process that occurs that turns something that everyone agrees is dead into something that everyone agrees is alive. Perhaps the actual point at which a person agrees something is alive would be different for each person but surly there is an event or point in time where each person will change their mind from believing it isn't alive to believing it is alive. I would imagine that the conversation would go something like: Person 1: ...and then this happens and, BANG, its alive. Person 2: I don't think it's alive, it doesn't do, such and such. Person 1: OK. Then this happens and NOW it's alive. Person 2: OK, it's alive. Person 3: No it's not, it doesn't....ETC... Surely at the end, you would end up with everyone accepting that it is alive and you would know exactly how it got there. No? Once again, sorry if I appear difficult, it's just that I want to know the nitty gritty. Thanks all. | |