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The Coelocanth

T

TheBeast17

Gone But Not Forgotten
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Can someone please explain something to me, because I'm confused (something that is very easy to do).

I watched a programme the other nite about the Coelocanth, and how reclusive and rare a fish it is. Lots of scietist type guys and gals were raving about movement of fins, and jelly filled sacks in the nasal cavity and stuff, and about how it might be the missing evolutionionary link between sea and land animals, due to it's hinged fins.

I was really getting intrigued by the theories that were being thrown around about evolution, and how it was first thought that the fish used the hinged fins as rudimentary legs on the sea floor.

Then something was said, almost as a throw away remark, that made absolutely no sense to me.

They started talking about how the fish had no spine. Instead it had a hollow grisely tube filled with a slightly pressurised oil.

Eh?! :confused:

How can this be a link between sea and land animals if it has no spine? No vertebrae, or spinal column, just a tube with oil in it. Nothing else about this was mentioned on the programmed.

Now, I'm probably missing something really obvious here, and I'll look really stupid (again, something not difficult to do) but how would that work on an evolutionary basis? Why would fish evolve from a creature with a spine to a creature that didn't have one (essentially), only to decide that when it got onto land that it really needed one?

I need a lie down.
 
errr hang on (sound of memory failing to start)

The last programme I saw seemed to suggest that they were more of a fork off of the "walking beastie" route. They developed the funny spine while their relatives crawled up on to the beaches.

not much of a reply is it?

Sorry:D
 
That's about what I remember as well, they were like a different branch of evolution that didn't go anywhere even though their relatives did so to speak..........
 
That makes sense.

I mean. if they were THE link between sea and land, why are they still here? So being a sort of evolutionary dead end sounds about right.

Cheers.
 
Originally posted by The Beast
That makes sense.

I mean. if they were THE link between sea and land, why are they still here? So being a sort of evolutionary dead end sounds about right.

Cheers.
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This is exactly what I was thinking. Also, I wouldn't be so keen to use them to support evolution myself, considering they have remained essentially unchanged for millions of years. They could almost be used as an argument against it, using a certain logic.
 
TorgosPizza said:
This is exactly what I was thinking. Also, I wouldn't be so keen to use them to support evolution myself, considering they have remained essentially unchanged for millions of years. They could almost be used as an argument against it, using a certain logic.
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That's why I don't understand why were told that we descended from monkeys.....if we did why are their still monkeys?
 
Oh man. We didn't descend from monkeys. We all descended from some big hairy guy climbing in trees okay. We just have a tendency to call hairy guys climbing in trees for monkeys cos we haven't got a better word. Monkeys aren't our ancestors, they are our cousins.
 
And coelocanths themselves live in the deep ocean, one of the most stable environments on the planet, so they haven't had to evolve. Evolution is driven by environmental pressure ie, by climate change or geological changes in the landscape. (The environment here has to be interpreted in the widest possible way, including all the other species in the biosphere, who themselves are trying to adapt to changing conditions.)
 
Thanks, rynner--I hadn't thought of it that way. But, then, I don't think about coelocanths very often. :) I still feel like it would better serve as an evolutionary model if it were extinct (not that I wish they were; it's kinda cool having them around). But like I said, I don't have it well thought out...just shooting from the hip.
 
Sounds like the guy who mentioned "missing link" was trying to make it simple for the non-biologists. What coelocanths have is a notochord and are chordates of the sub-phylum cephalochordata vere as ve of course are in the sub-phylum vertibrata. All latin means that a fish that had lobe fins related to an ancestor of coelocanth got a spine & some of its decendants kept the lobe fins and went walkies.

Missing links are transitional forms and are the rarest finds in paelantology, in fact I'm not sure any unequivocal examples have ever been found.
 
The chances of this Coelocanth fish being the actual fish that climbed out of the water and became our early ancestors are doubtful after all if it did infact leave the water what is it still doing here? I have seen evidence to support the fast that fish did infact come out the water and evolve but that doesnt mean that all mammals do come from fish, maybe fish come from mammals? or maybe we are results of 2 totally unrelated single cell organisms evolving at similar times to 2 totally different species of animal.
Im sure the only way we can be for sure is if one of us was actually there, but until the day one of us invents a time machine we will just need to do what the BBC does and guess and pretend to the world that is how it happend.
 
Was the scientist saying that the spinal column was the transitionary period between the cartelidge fish (e.g. sharks) and normal fish which later crawled out of the sea?
 
There's an easy mistake when talking about Darwinism/Evolution to see it exclusively as an onward and upward progression of life from simple origins - what it actually talks about is adaptation to environment.

Organisms adapt to their environment, and there's no real reason for a perfectly-adapted animal to change. It won't become a more advanced animal simply for the sake of it, but may become more complex in response to challenges it faces from a change in environment.

Natural selection will weed out those who aren't able to adapt, so the genetic lines of those who ARE able to adapt will be favoured, and thus more likely to make up the majority of the species, and over time, the entire species itself.

Evolution comes into effect when the species is forced to adapt to new circumstances - in the "monkeys" example given, the reason that we still have monkeys is because they're just as evolved as us, but fit into different environmental niches. We didn't come from gibbons, chimpanzees or gorillas, but we share common ancestry, and have developed in different directions to exploit different environments.

Coelocanths are also doing pretty well in their own little niche - they don't need to change to get what they need from it. Modern scientific thought has ruled out the Coelocanth as any "ancestor" of land species - they're just a fish with some peculiar adaptations, and their "limb/fin" look was a red herring that confused early interpreters into thinking that they must have represented a transitional phase between land and sea life.

Monkeys are ideally suited to their lifestyle and environment, and there's no impetus for change since they are quite well adapted to a life in the trees.

I heard an explanation of man's success due to the fact we weren't as successful as the other primates, and were driven out of the trees/forests by competition from others.

The Chimpanzees and Gorillas are again just as evolved as we are, and are pretty well suited to an untouched habitat - perhaps their ancestors out-competed us in the forest habitats, and forced us out on to the savannah. In doing so it provided challenges which shaped the human species into a more complex animal.

In short, don't assume that a more evolved animal is necessarily more complex, intelligent or articulate - you have to bear in mind that evolution is adaptation to a niche, and the complexity of the organism depends on the nature of the niche it exploits, and its competitors. Without a necessity for change, a perfectly-evolved animal can be very simple in nature, which is why we still have very simple forms of life all around (and on) us.
 
Thanks,

I new there was something fishy going on!

But did I not see a Documentary on the Discovery chanel recently about this fish?

I am sure that it mentioned that no direct link to Eevolution has ever been found. Although the fish has the charecteristics to fit the model for this theory I think they mentioned something about the arangement and number of bones being wrong.

If the theory is true, why do we always say that Man decended from Apes, and not that we decended from fish?

Hmmmmm?
 
Probably because ape-like hominids are only one step or two back, fish are waaaaaaaaaay back. Besides, would you like to be told your family was goggle-eyed and smelled of ammonia?
I'm sure I have a book somewhere with the name of the cheif suspect in the 'perambulatory piscean' stakes, but I suspect it has taken up residene in the Temple of Doom (my loft).
 
Guru_saj said:
I heard an explanation of man's success due to the fact we weren't as successful as the other primates, and were driven out of the trees/forests by competition from others.
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I heard also that another reason we humans did so well was that we (well, most people of most races) retained the ability to digest milk proteins into adulthood, unlike most other mammals, and we able to take advantage of dairy products. Was this something that evolved due to those unable to digest milk being dietarily disadvantaged or a just a fluke?
 
How the hell did they figure that one out? I mean, that fully grown humans could still drink milk? What were they doing? I hope it's not what I think, even I wouldn't do that, and I'm a pervert!
 
Late breast-feeding is an effective contraceptive in many circumstances. Is this how humans developed their lactate tolerance?

Evidence of this (before I'm swamped with post's about "... my friend got pregnant whilst breastfeeding"here
 
It has been postulated that man's intellectual development is partially due to food processing and dietary adaptations.

Complex foods (such as many types of plant matter) are difficult to digest, and take a large and complex gut system (such as those found in ruminants) to extract the nutrients.

Having a large gut means that it uses a lot of energy - combine this with a large brain, and you would have an animal that required a massive calorific intake, and thus would be extremely vulnerable to food shortages, such as the ones which still affect humans today in some parts of the world.

The human brain is large and has grown in complexity, whilst our gut has become shortened and less complex - look at the atrophied appendix.

By shifting our diet towards more easily-processed food, and by the introduction of cooking, which effectively pre-processes our food for us, we have been able to maintain a large brain without the additional expense of a large gut, too. In consequence, the calories saved by the shortened gut has allowed the brain to pick up the deficit.

Perhaps the use of dairy products is just another way of getting easily-digested food into the equation, allowing our greedy brains to continue to flourish.
 
I wonder how long ago the discovery program was made before it aired. The link to fish for evolutionary discussions is age old. The lobe fish were thought to have been the fish that were the first creatures to leave the sea for a land environment. During their initial existence during the Pangean area (I think), the topographical models show that this was a period of extreme change involving the drying up of water systems and the expose of land masses. It was believed that the lobe fish, as well as the lung fish evolved into their forms in order to be able to traverse small patches of dried land in order to get from one pond to the next. The jawed fishes are also famed to be linked to terrestrial evolution. Prior to the jawed species of fishes, most fish just sucked away at things to get their nutrition. As jaws developed, so too did the ability to hunt and capture prey, which in turn required more brain power, which caused the brain to evolve, and on an on. There has been some very recent scientific evidence to suggest that the lobe fish however did not develop their skeletal lobes in order to help them traverse onto land, but rather as the seas dried up they were forced into more and more shallow water, which was weed filled, so they developed these limbs as a means of pushing aside the weeds so that they could swim freely, etc. Which I believe is the way that they use these lobes today. There is a VERY good book on the new evolutionary arguments which covers lobe and jawed fish in detail. I cannot remember it right now but I have it at home and will get the name and post it later.
 
Yeah I have. And good God now I'm a believer! It sounds to me like it could explain a lot of things. But I haven't really heard any of the counter arguments though.
 
Guru_saj said:
In short, don't assume that a more evolved animal is necessarily more complex, intelligent or articulate - you have to bear in mind that evolution is adaptation to a niche, and the complexity of the organism depends on the nature of the niche it exploits, and its competitors.
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Its that Spencerian 'survival of the fittest' that gets people putting mistaken emphasis on complexity, but the confusion has been compounded with misleading images like the 'evolutionary ladder'. If you buy Darwinian evolution then we are not at any kind of apex. There is no destination or object to evolve towards except continued existence. My favourite example is that before Origin of Species Darwin was fond of Barnacles and he discovered a species living in a secluded bay that had evolved to become really nothing more that stomach and sex organs. Now there's something to aim for. :D
 
Just to chime in.

Evolution is not an invisible hand guiding animals to perfection. A freak is born, whose freakish tendancies some how confer an advantage in one way or another.

Over time, the slight advantage compounds and there is a transition from "freak" to "new animal". The line is pretty arbitrary.

Now, this freak may or may not out compete it's predecessor. There is no sudden transition. If there is one, it is usually gradual except in exceptional circumstances.

A species that evolved from another could co-exist: if they fill a slightly different niche, have different territories, or what have you.

But all evolution is, is advantage. That's all it is, really.

Evolution has not stopped. In fact one could argue that mankind has created a sort of "punctuated equilibrium" similar to those that have, in the past, spurred evolution. Notice that animals have begun to adapt to urbanization.

Not only that, but we are intelligent. Our intelligence and pack behavior is our conferred advantage. So, in the end, mankind may cause its own downfall naturally. The dumb kodiak bears, the ones who do not know what man means, will die. The slightly smarter ones will not. They will actively evade hunters. Hunters will try to use their intellect to overcome it. The slightly less intelligent bears may , again, have enough of an advantage to survive and so on and so on until one day a kodiak bear hides in a blind to ambush a hunter.

That is one slightly goofy theoretical example, but evolution itself is no mystery. It can be applied to almost anything, with the right process, to deliver the best candidate for a given task.

Given enough time, mankind will branch into distinct species. If society continues today, we may have for instance homo sapiens gates , a very intelligent sub species noted for its small size. Or, homo sapiens spears known for looking good, but thoroughly unintelligent and unable to sing. Or homo sapiens jordan, a very tall and strong subspecies that is incredibly gifted at sports.

That more then anything scares me. What humanity has, in many ways, arbitrarily deemed "desireable" traits, and are, at the moment, actively pursuing attempts to breed these traits into ourselves.
 
Actually, humanity won't grow into subspecies as you describe. Enough 'cross-breeding' of smart, attractive, and athletic people occur that we're still one big melting pot. Also, the traits described make one more successfuel financially, but not necessarily reproductively.
 
I disagree.

Evolution is a random process that ends in a result tailored to specific ends.

I had a really good article on evolutionary computing, which uses mimiced biological process, but anyways...

There are certain traits that will allow you to breed more successfully over a long period of time. As civilization and progress spread, those same ideals will, as you said, become a melting pot.

Eventually we will have a homogenous world society. However, after that, certain traits WILL lead to outcompetition among rivals.

Wealth. Chicks love wealth. Let's be honest, here. I'll pose a simple question: take your current boy friend. Would you prefer he be wealthy? The answer is, yes.

Same probably for famous. Same probably for another talent that leads to success in society, i.e. musician, athlete, etc.

Over a period of time the traits WILL become more predominant.

Where do most people meet their sposes? University or work. Same basic interests.

Where do the rest meet their spouses? Usually through various means of social interaction. Yet can you honestly say that a women would not pick an athlete with money, over average joe?

Maybe, maybe in a lot of cases. But there is the preference.

Mankind WILL divide into subspecies. The way our society is set up, in 2 million years, if we're still around, we WILL have a caste system similar to other colony animals (ants).

Well, not WILL. But very likely.
 
I find three problems with that idea, assuming we're around in 2 million years.

1) We won't be living in Earth, so theres the added in, unknown variable of what living abroad in space will provide.
2) Genetic engineering. Preferred traits will no longer be due to random chance, but conscious choice.
3) It assumes future civilization is not only predictable, but will be the same as our current one.

We may evolve into ants. But it's far from positive.
 
Yeah, it is FAR from positive.

And yes, given the above things, I agree.

However we'll still evolve into subspecies.

Living on mars? Let's geneer tolerance to lower gravity.

On a planet with more Gs? Shorter, sturdier.

We may gain control of our own evolution, but the process will continue.

Etc.
 
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