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Author Topic:   Intermediates
ZenMonkey
Member (Idle past 4501 days)
Posts: 428
From: Portland, OR USA
Joined: 09-25-2009


Message 31 of 52 (541102)
12-31-2009 12:39 PM
Reply to: Message 1 by AndrewPD
12-28-2009 10:20 AM


Since no-one else has.
I should point out one thing that hasn't been mentioned yet.
EVERY individual organism is an intermediate.
Your parents were intermediates between you and your grandparents. Your grandparents are intermediate between your parents and your great- greatgrandparents. And your great- greats were intermediate between you and your great- great- great- greatgrandparents. And so on.
Every individual in that lineage was successful enough to leave at least one offspring. And that offspring likewise. Every individual was different from his or her parents, and his or her offspring likewise.
The difference between any two adjacent generations would be small - often smaller than the difference between one individual and another from the same generation.
Any genetically derived change in an individual from one generation to the next that increased the odds of survival and reproduction in the current environment would be more likely to be passed on to subsequent generations. The genes from which that trait originated would then increase in the general poplulation of individuals sharing a gene pool.
Once a change in a population proved to provide a significant reproductive advantage in the current environment, similar genetically derived changes of the same type would conitunue to accumulate in the same direction. For example, if increased fur density or longer limbs were advantageous in a particular environment, then fur would continue to get thicker or limbs longer until there was no further advantage to be derived.
These geneticaly derived changes in the frequency of traits in a population can accumulate over time. Again, each generation will be slightly - but just slightly - different from the one that came before. There will be no clear line where you can say that one individual was of one species and its offspring was of a different one. However, over enough generations, multiple changes will accumulate to such an extent that eventually one generation will be different enough from its ancestors to be considered a new species.
This is a brief and incomplete description, but one that - if you really take the time to think about it - will be helpful in clarifying some issues for you. But keep in mind - every individual is an intermediate between its ancestors and its descendents.
Edited by ZenMonkey, : No reason given.

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Blue Jay
Member (Idle past 2688 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 32 of 52 (541105)
12-31-2009 1:18 PM
Reply to: Message 28 by AndrewPD
12-31-2009 11:35 AM


Reinventing the Wheel
Hi, Andrew.
AndrewPD writes:
For a human to survive in its current body it has to have good eyesight immediately it cant afford to wait for beneficial mutations.
Do you have reason to believe that the intermediate(s) between bonobos and humans had poor eyesight?
So, what makes you think humans had to do any waiting for beneficial mutations? You don't have to evolve good eyesight if you inherited it from your ancestors, do you? That would be reinventing the wheel.
-----
AndrewPD writes:
An owl has to have good night vision as well as the ability to fly.
The ability to fly long predates the emergence of the first owl, so the owl did not have to re-invent the wing, did it? So, the ability to fly is effectively a non-issue for owls.
As for night vision, please reread what I wrote in Message 14. Form can follow function, and function can follow form. In fact, that can follow one another closely enough that it's hard to distinguish one from the other.
Owls might have been forced to hunt at night, and, once there, experienced strong selective pressure for good night vision.
Or, some owls may just happened to have had better low-light vision, and were thus more successful at night.
Most likely, it was some combination of both happening simultaneously.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

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Blue Jay
Member (Idle past 2688 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 33 of 52 (541107)
12-31-2009 1:24 PM
Reply to: Message 27 by AndrewPD
12-31-2009 11:24 AM


Ebb and flow
Hi, AndrewPD.
Andrew writes:
What I am saying here is that the ancestors of humans had to be healthy enough to survive long enough to produce, so why would they die out at all?
How come Napolean doesn't still rule Europe?
He routed just about everybody on the battlefield, didn't he?
Everyone has their peaks. That doesn't mean they always stay there, does it?
Edited by Bluejay, : Added subtitle and last line.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

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Tanypteryx
Member
Posts: 4319
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 5.4


Message 34 of 52 (541110)
12-31-2009 2:32 PM
Reply to: Message 24 by AndrewPD
12-31-2009 11:04 AM


AndrewPD writes:
A mollusc doesn't need a humans eye and the eye of a cat will never develop into a humans eye.
What an organism needs does not affect how the species evolves. Evolution can only work with what is already there, through slight modifications (mutations) of structural or developmental genes and subsequent selective pressures.
Molluscs are an interesting group. There are many different types of eyes within Phylum Mollusca ranging all the way from no light sensitive organs, to the simple eyes of Snails and Slugs, the the complex eyes of Squids and Octopuses (has a pupil, lens, and retina, similar to vertebrate eyes).
No one is suggesting that cat eyes would develop into human eyes, but in the future cat descendent's eyes may be different due to new mutations that may spread through a population.
AndrewPD writes:
But to get from a simpler eye to the human eye you would surely need numerous beneficial mutations and at no stage from simpler eye to extremely complex eye could the mutation create a disadvantage.
It is true that there have been numerous beneficial mutations between simpler ancestral eyes and modern human eyes.
Interestingly, we know that mutations that cause a disadvantage do not necessarily interrupt the development of a more complex eye. Only if the disadvantage keeps the organism from surviving and reproducing will those mutations be removed from the gene pool. In the human population, for example, there are numerous mutations that cause impaired vision and that are passed on to offspring. It is even possible that disadvantageous mutations may confer an advantage to descendants in the future in a different environment.
AndrewPD writes:
If you see a professional Tom Cruise look-alike you don't assume he's directly related to Tom just someone randomly with a striking resemblance.
But we would know that he is the same species as Tom, and we could even surmise (if his resemblance is natural) that some of the genes controlling development of features are similar to Tom's.

What if Eleanor Roosevelt had wings? -- Monty Python
You can't build a Time Machine without Weird Optics -- S. Valley

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DrJones*
Member
Posts: 2283
From: Edmonton, Alberta, Canada
Joined: 08-19-2004
Member Rating: 5.7


Message 35 of 52 (541113)
12-31-2009 3:31 PM
Reply to: Message 25 by AndrewPD
12-31-2009 11:15 AM


So I see no problem in looking at an intermediate species and having the same sense of speculation.
Why? were you planning on fucking said intermediate species? You're making the assumption that what is aestheticly pleasing to you matters at all to the organisms that are reproducing with eachother.

It's not enough to bash in heads, you've got to bash in minds
soon I discovered that this rock thing was true
Jerry Lee Lewis was the devil
Jesus was an architect previous to his career as a prophet
All of a sudden i found myself in love with the world
And so there was only one thing I could do
Was ding a ding dang my dang along ling long - Jesus Built my Hotrod Ministry

Live every week like it's Shark Week! - Tracey Jordan
Just a monkey in a long line of kings. - Matthew Good
If "elitist" just means "not the dumbest motherfucker in the room", I'll be an elitist! - Get Your War On
*not an actual doctor

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RAZD
Member (Idle past 1395 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 36 of 52 (541128)
12-31-2009 7:45 PM
Reply to: Message 27 by AndrewPD
12-31-2009 11:24 AM


Of Pelycodus and Dodos
Hi again, AndrewPD, thanks.
What I am saying here is that the ancestors of humans had to be healthy enough to survive long enough to produce, so why would they die out at all?
Because every generation of every species known to man dies out and is replaced by the following generation. Some species take longer than others, some are very fast. A human generation is ~20 years, and primitive man rarely lived into the 30's.
Now, when there is selection pressure, and we follow a species over an extended period of time we see a gradual change in the frequency of hereditary traits in the breeding population from generation to generation.
This change can be very gradual but still form a long term trend. At every stage the population is composed of living, breathing and breeding individuals, but the make-up of individuals is what is changing.
The problem may be due to the subjective and sometimes artificial classification of species, rather than to any real replacement mechanism. Take Pelycodus as an example:
A Smooth Fossil Transition: Pelycodus
quote:
The numbers down the left hand side indicate the depth (in feet) at which each group of fossils was found. As is usual in geology, the diagram gives the data for the deepest (oldest) fossils at the bottom, and the upper (youngest) fossils at the top. The diagram covers about five million years.
The numbers across the bottom are a measure of body size. Each horizontal line shows the range of sizes that were found at that depth. The dark part of each line shows the average value, and the standard deviation around the average.
The dashed lines show the overall trend. The species at the bottom is Pelycodus ralstoni, but at the top we find two species, Notharctus nunienus and Notharctus venticolus. The two species later became even more distinct, and the descendants of nunienus are now labeled as genus Smilodectes instead of genus Notharctus.
As you look from bottom to top, you will see that each group has some overlap with what came before. There are no major breaks or sudden jumps. And the form of the creatures was changing steadily.
A "lumper" could say that all the fossils from Pelycodus ralstoni to Pelycodus jarrovii are all one species that is just changing some hereditary parameters, including size. All the upper fossils are descendants of the original population at the bottom, so the {breeding population} has not "died out" - just old members died after giving birth to following generations.
Note that this trend covers millions of years and several mutations that are cumulatively selected by the selection pressure that is favoring the survival and breeding of larger individuals.
Notice also, that while the general trend persists, that the progression from Pelycodus ralstoni to Pelycodus jarrovii staggers back and forth from the mean progression line.
So why did Pelycodus ralstoni die out by the time Pelycodus jarrovii lived?
As I mentioned with the Dodo it died out and left no beneficial mutations because it wasn't wily enough.
Wiles and the possibility of beneficial mutations had nothing to do with this: the Dodo evolved into a flightless bird over many generations, because a flightless bird is less likely to be blown to sea from an island, where the threat to survival is higher; the Dodo was hunted to extinction in the course of a generation or two - way too fast for evolution to provide an answer to the people that (a) found the island and (b) needed a large food source to provide for their exploring vessels.
Interesting read, btw:
The Song of the Dodo:
quote:
In a wonderful weave of science, metaphor, and prose, David Quammen, author of The Flight of the Iguana, applies the lessons of island biogeography - the study of the distribution of species on islands and islandlike patches of landscape - to modern ecosystem decay, offering us insight into the origin and extinction of species, our relationship to nature, and the future of our world. --This text refers to an out of print or unavailable edition of this title.
The book is an excellent introduction to island bio-geology, and to the work of Alfred Russell Wallace, the "other" Darwin. The title comes from the fact that no record of what the song of the Dodo was like - they were hunted to extinction that fast.
Rather they are replaced by a completely different species.
Extinct species are replaced at all. If the ecology continues to exist, then other organisms will become adapted to it if they can take advantage of the void left by the extinction. New organisms are unlikely to resemble the extinct species in any way.
Message 28: As I have said a snake doesn't need a human eye so why would you class a human eye as "better"?
A snake will never evolve a better eye because it doesn't need one.
Humans don't have better eyes because they need them, they have better eyes because their ancestors were able to take advantage of mutations not necessarily available to snakes (which still have a very similar eye, btw).
Evolution is opportunistic rather than need driven. Natural selection does not cause a needed mutation to occur, rather it selects the best that opportunity provides.
The human eye is part of a bigger package that all has to survive not just an eye mutation. But wonderfully all the neccesary mutations coincide.
And every intermediate stage is represented by an existing species, thus demonstrating that no intermediate stage is worthless to the organisms involved. Consider the slight but measurable difference between a person who is blind and one who can perceive light versus dark.
But I don't think the presence of a simpler eye or knee proves that you can remove a part of the human eye or knee and it still function.
That's not the issue. The issue is how the eye or the knee evolved from what was available before. Nobody is saying that you can remove parts and have an equally functional eye, just that the developing eye only needs to provide a survival and breeding advantage to the organism at each stage.
Enjoy.
Edited by RAZD, : T
Edited by RAZD, : subtitle

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

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Blue Jay
Member (Idle past 2688 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 37 of 52 (541131)
12-31-2009 8:23 PM
Reply to: Message 27 by AndrewPD
12-31-2009 11:24 AM


Re: steps in understanding
Hi, Andrew.
Andrew writes:
I am saying that it is precisely because a mutation has to survive through being beneficial that it is strange for an intermediate to die out.
I'm not sure I understand what your problem is with intermediates going extinct. Is it because you think they had to have been good enough to survive, so they should have survived?
"Survival" isn't a monochromatic entity. Times change, predators change, competitors change, the climate changes, the food supply changes, the water supply changes, diseases change, etc.
Given all this change, it shouldn't surprise you that something that used to be well-adapted and successful could later become unsuccessful.
One other thing that you're not considering is that the intermediates actually are still surviving. They're our ancestors, remember? So, some of them did survive... as us.
-----
AndrewPD writes:
As I mentioned with the Dodo it died out and left no beneficial mutations because it wasn't wily enough.
So, do you think everything that went extinct must have been stupid, weak and/or ugly?
So you also think that everybody who has died must have been stupid, weak and/or ugly?
-----
AndrewPD writes:
Things that go extinct don't appear to be replaced by better models. Rather they are replaced by a completely different species.
How would something that goes extinct evolve into a "better model"? It went extinct, remember?
The only way a species gets replaced by a "better model" is if it diverges into two species, and then one of the two goes extinct.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

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Nuggin
Member (Idle past 2483 days)
Posts: 2965
From: Los Angeles, CA USA
Joined: 08-09-2005


Message 38 of 52 (541137)
12-31-2009 11:24 PM
Reply to: Message 28 by AndrewPD
12-31-2009 11:35 AM


As I have said a snake doesn't need a human eye so why would you class a human eye as "better"?
A snake will never evolve a better eye because it doesn't need one.
The human eye is "better" because it can focus binocularly, see in color, see further and with greater detail and it has eyelids.
You keep saying "snakes don't need better eyes" indicating that you are missing out on some important core concepts about this topic.
Say you have a population of rattlesnakes in a valley in New Mexico. One of those snakes has slightly better eyesight than the others. Is he MORE or LESS likely to catch food/avoid predators?
More.
Therefore is he MORE or LESS likely to survive long enough to reproduce.
More.
Therefore are his offspring MORE or LESS likely to make up a larger part of the population in the next generation?
More.
The snake doesn't "need" a better eye, but the snake with the "better" eye is going to out compete his neighbor and pass that trait on.
For a human to survive in its current body it has to have good eyesight immediately it cant afford to wait for beneficial mutations.
You are assuming here that humans evolved a body and THEN gained eyes. What leads you to believe this? Do you think that chimps don't have eyes?
But I don't think the presence of a simpler eye or knee proves that you can remove a part of the human eye or knee and it still function.
Again, you are completely failing to understand the term "function".
You are assuming that an eye which doesn't function as well as yours is useless.
I've already explained this part to you twice, so I'm going to explain it a different way.
If you and I are part of a secret government experiment and I am given the eyes of an eagle, I can see MUCH better than you can.
Your eyes are now not as functional as mine. Compared to mine they are worthless. You can't even see things a mile away, let alone read letters off a page at that distance.
Does that mean your eyes are now useless because mine are better than yours?
You are assuming that anything less than human vision is blindness. I'm taking that to the next level. Anything less than eagle vision is blindness.
Can you see the error in this argument?

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Nuggin
Member (Idle past 2483 days)
Posts: 2965
From: Los Angeles, CA USA
Joined: 08-09-2005


Message 39 of 52 (541139)
12-31-2009 11:29 PM
Reply to: Message 25 by AndrewPD
12-31-2009 11:15 AM


Ummm,,,,, hello
Andrew,
I present you with a post with a very nice picture demonstrating a girl who is a "freak" because he features put her a few steps ahead on the evolutionary chain.
I can't help but notice you ignored the post.
Do that mean you concede the point? If so, say so.

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Dr Adequate
Member (Idle past 274 days)
Posts: 16113
Joined: 07-20-2006


Message 40 of 52 (541142)
12-31-2009 11:39 PM
Reply to: Message 25 by AndrewPD
12-31-2009 11:15 AM


Yes aesthetics and subjective taste is controversial. But if you took a sample average I am sure that you'd find people thought a butterfly was generally attractive and a moth less so.
Apparently one of the reasons we find people attractive is because of signs of fertility.
So if we find a deformed human unattractive it is because they don't look fully functional.
So:
(1) Are moths less functional then butterflies?
(2) You argument is still self-contradictory. On the one hand you claim that intermediates are uglier than modern species. Then you equate ugliness with poorer functionality. And then you wonder why intermediates were superceeded by modern forms. Well, if your premises were correct, you'd have supplied your own answer to that.

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Dr Adequate
Member (Idle past 274 days)
Posts: 16113
Joined: 07-20-2006


Message 41 of 52 (541144)
12-31-2009 11:42 PM
Reply to: Message 27 by AndrewPD
12-31-2009 11:24 AM


Re: steps in understanding
What I am saying here is that the ancestors of humans had to be healthy enough to survive long enough to produce, so why would they die out at all?
Because they couldn't compete with us.
The vacuum-tube computer had to be useful or no-one would have built one. So why is no-one building them today, huh?

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websnarf
Junior Member (Idle past 5155 days)
Posts: 9
From: San Jose, CA, USA
Joined: 11-30-2009


Message 42 of 52 (543815)
01-20-2010 9:54 PM
Reply to: Message 1 by AndrewPD
12-28-2009 10:20 AM


quote:
This is my personal observation that keeps me skeptical of evolution.
Evolution is science. Having an opinion about it is kind of sad. Do you have an opinion about whether or not electricity works to power your computer? Regardless of what your opinion is, do you think your computer would work by electricity anyways?
quote:
Why did the creatures created by the stages of evolution between one species and the next die out.
There are no known animals that are immortal. They died, probably by the same process that any other animals die.
You probably mean to ask why our ancestor genes did not survive in a representative lineage to this day. Its mostly just "survival of the fittest" that's going on.
Ardipithecus ramidus was probably defeated by the contemporary chimpanzee ancestor soon after they spawned australopithecus because they lived in the same place and ate similar food (and the chimpanzee is alive today while a forest dwelling ardipithecus offspring is not).
From Australopithecus to Homo habilis to Homo ergaster to Homo heidelbergensis to Archaic Homo sapiens to modern Homo sapiens, each one was simply better at surviving or obtaining food than its immediate predecessor and they all lived in the same place (Africa) while there was not a surplus of food.
Homo neanderthalis was a sister species that we have pretty good evidence that we coexisted with (by immigrating to their lands in europe about 40-50K years ago), then directly out-competed for resources (including the possibility of direct, but likely limited, warfare.)
For side-species like Homo georgicus, Homo pekeninsis and Homo floresiensis they appear to have died out for no obvious reason. However, these guys spread out to all sorts of weird places (Georgia, China and Indonesia) where climate changes had far more drammatic effects on the animal fauna.
Things like Kenyanthropus, Homo rudolphensis, and so on, they probably could have been done in by climate or (like the Neanderthals) direct competition with their contemporaries along our lineage.
quote:
Simple and extremely complex organisms coexist together. So why couldn't a less developed human survive?
Homo floresiensis came pretty close. They might have lived as recently as 13K years ago. But as I explain above, one of the main reasons (for the non-floresiensis) is that we Homo sapiens were a little too good at getting access to the limited food just before our less adapted competitor ancestors were.
quote:
It must have survived long enough to evolve into us.
If I evolved the ability to breath under water that would not lead to all other humans dying out.
Correct. Similarly, I don't think Australopithecines were involved in the extinction of Ardipithecus, nor do I think Homo heidelbergensis was the end of Homo pekinensis. In those cases other environmental factors, or in fact other species entirely could have caused their extinction.
quote:
To me species look complete and not on the verge of any kind of speciation. Plus it must have taken millions of very gradual mutations to create us.
That doesn't make any sense. There are never any overt signs of a species "speciating" except when put in direct comparison to what came before and after it (at which point *every* species looks like its about ready to speciate.) How do you explain Homo georgicus, for example? It looks like a Homo habilis from the waist up - spinal column, and a Homo ergaster from the waist down + spinal column. But at the same time, it also just looks like yet another complete ancient ancestor for us that could just stand (no pun intended to the anthropologically literate) on its own.
quote:
So we can't have gone from monkey to human overnight which makes it essential that intermediates hang around for a long time.
Humans are a kind of ape. By the old taxa we are not a kind of monkey and didn't come from one. From a more cladistic point of view of course, we are all monkeys. Either way your statement makes no sense.
Humans and chimps spawned from a common ancestor about 7 million years ago, that was likely contemporary to something like Sahelanthropus tchadensis. Both proceeded in very gradual steps to evolve into their current modern forms -- and that *IS* what the fossil record is showing us. Under usual evolutionary conditions we would continue to evolve, and thus are ourselves merely a transitional form to what our offspring eventually would become.
But its possible that we have put an end to really serious evolution of our own species because of our memetic-based survival mechanisms (we make and control our own food supply, and we also control the affects of the environment upon us). Though simple things like women evolving to have menopause later in life seems like a likely adaptation if the western world continues its kind of modern life-style (at the very least it would be highly selected for).

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Replies to this message:
 Message 43 by New Cat's Eye, posted 01-21-2010 10:46 AM websnarf has replied

  
New Cat's Eye
Inactive Member


Message 43 of 52 (543860)
01-21-2010 10:46 AM
Reply to: Message 42 by websnarf
01-20-2010 9:54 PM


Hello websnarf, welcome to EvC.
I'm not trying to argue that you're wrong, but I'd thought I'd bring up some things.
There are no known animals that are immortal. They died, probably by the same process that any other animals die.
First off, check out this animal <--clicky:
quote:
Turritopsis nutricula is a hydrozoan which reverts to the polyp stage after becoming sexually mature. It is the only known case of a metazoan capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary stage. It does this through the cell development process of transdifferentiation. Theoretically, this cycle can repeat indefinitely, rendering it biologically immortal until its nerve center is removed from the rest of the body.
Neat, huh?
I'd also like to point out another thing about immortality and death. Think of the asexual reproduction of a bacteria:
The original cell divides into two new cells. The original one hasn't really "died". And the new cells are of the same 'stuffs' as the original. In that sense, bacteria is kinda immortal... "kinda immortal", heh
Here's how wiki phrases it:
quote:
Bacteria are said to be biologically immortal, but only as a colony. An individual bacterium can easily die. The two daughter bacteria resulting from cell division of a parent bacterium can be regarded as unique individuals or as members of a biologically "immortal" colony. The two daughter cells can be regarded as "rejuvenated" copies of the parent cell because damaged macromolecules have been split between the two cells and diluted. In the same way stem cells and gametes can be regarded as "immortal".
So not everything really dies and some things can be said to be immortal.
And to counter my own argument, I present this:
https://www.youtube.com/watch?v=QMHQQvBs6o4

This message is a reply to:
 Message 42 by websnarf, posted 01-20-2010 9:54 PM websnarf has replied

Replies to this message:
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websnarf
Junior Member (Idle past 5155 days)
Posts: 9
From: San Jose, CA, USA
Joined: 11-30-2009


Message 44 of 52 (543869)
01-21-2010 12:01 PM
Reply to: Message 43 by New Cat's Eye
01-21-2010 10:46 AM


Hi Catholic Scientist.
I would just like to point out that single celled organisms are not "animals".
Clonal colonies ( Clonal colony - Wikipedia ) are also an example of a potentially "immortal" organism. However, I picked the word "animal" quite consciously.

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Replies to this message:
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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


(1)
Message 45 of 52 (543913)
01-21-2010 7:31 PM
Reply to: Message 44 by websnarf
01-21-2010 12:01 PM



Planaria
arguably fit this criteria. They don't bud per se but they can regenerate multiple new organisms from small sections of themselves, even when cut into hundreds of pieces.
Edited by Wounded King, : No reason given.

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