Religion/Philosophy Thread
- Thread starter TAFJonathan
- 231 comments
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- 3,823
Evolution is a given as far as I am concerned (I was raised Roman Catholic as well) There is just too much evidence to deny that this is the case. You don't need to be a scientist to draw your own conclusions to this though, as evidence is all around us. Want to see Evolution in action? Watch the Olympics. With every successive Olympics you will (generally) find that athletes continually grow larger, stronger, faster and so on and so forth. (There is more to this, such as training, but those basics are still true)
If you are looking for a good read, check this site out: http://www.literature.org/authors/darwin-charles/
If you want to learn about Evolution, you might as well learn it from the source
If you are looking for a good read, check this site out: http://www.literature.org/authors/darwin-charles/
If you want to learn about Evolution, you might as well learn it from the source
- 3,823
No, but lot's of things that we learn as American's get tied into Religeon from an early age (...One nation under God, indivisible, with liberty and justice for all...)
Sometimes it might seem as though we think we are exclusive, but for the most part the combination of God and country are Automatic to many people. (Which isn't really a bad thing, as it keeps most of us Unified in various ways. This was especially true during World War I and II.)
- 34
I do my best to be a good person. I'm of the opinion that if you do good then good things happen to you. I became interested in Christianity a couple of years ago and enjoyed the principles of it but a few things put me off in the end.
I'm not saying I'm right or wrong, but this is what works for me. If anyone wants to have a shot at changing the way I think, please do!
- Religon has alot to answer for. So much bloodshed has occured and is still going on because different factions believe their god is "the right god" or they think that they are doing god's work.
- Unless I am a really bad person, why should I ever fear God? Why would he/she/it want to do me harm?
- The Church of England seems to be more of a business than anything else to me. Also, I believe that Church should be somewhere to pray AND to share ideas, plan and execute actions to better the lives of those in the community, not just turn up and read a script because it's "the right thing to do". I also think that some people just go to show their faces
I'm not saying I'm right or wrong, but this is what works for me. If anyone wants to have a shot at changing the way I think, please do!
- 34
Tom, I understand that completely.
It's a great thing that America still does it's best to instill morality in it's citizens from an early age. Alot of us had to make up our own minds from childhood (which is also a good thing, as it promotes the freedom to think and feel in the way you want to). I would say that most families that I know are good people but are not deeply religious. From what I know of America, most families are and know nothing different.
Please, tell me if I'm wrong.
It's a great thing that America still does it's best to instill morality in it's citizens from an early age. Alot of us had to make up our own minds from childhood (which is also a good thing, as it promotes the freedom to think and feel in the way you want to). I would say that most families that I know are good people but are not deeply religious. From what I know of America, most families are and know nothing different.
Please, tell me if I'm wrong.
- 1,190
EXACTLY! ....evolution is a given .....i think some people misunderstand and think it is something that happened along time ago .....NO! ....evolution is happening all the time ......Natural Selection, Mutations, Recombination, HELLO? .....anyways it's just like you said; athletes are getting better at what they do (ex. hockey) and people are getting smarter: to attend university 50 years ago, all you had to have was the desire and half a brain .......now if you want to pursue a professional program you need a 98% average to even get looked at ......it's all about competition and the struggle to survive .....2 concepts which deal with evolution quite nicelyOriginally posted by Tom McDonnell
Evolution is a given as far as I am concerned (I was raised Roman Catholic as well) There is just too much evidence to deny that this is the case. You don't need to be a scientist to draw your own conclusions to this though, as evidence is all around us. Want to see Evolution in action? Watch the Olympics. With every successive Olympics you will (generally) find that athletes continually grow larger, stronger, faster and so on and so forth. (There is more to this, such as training, but those basics are still true)
If you are looking for a good read, check this site out: http://www.literature.org/authors/darwin-charles/
If you want to learn about Evolution, you might as well learn it from the source
- 8,542
- Tx, Alamo City
- XRaptor529
Well i would just like to say that im a Roman Catholic and yet i hardly ever go to church. I dont know i think im just not too in to the whole idea of going to church and sitting down for so many hours at a time. But thats really no excuse. I did at one point go to church on a regular basis but i never really understood what was being said. It was a all spanish church and thats all where my mother would ever go to. 
Maybe if we went to an english speaking church i would enjoy it much more. But that was then and this is now i cant find the time to do that. I think all i need is a little push to start me off on going to church every sunday and anyother days i should go.
well anyways thats just my 2 cents.
Maybe if we went to an english speaking church i would enjoy it much more. But that was then and this is now i cant find the time to do that. I think all i need is a little push to start me off on going to church every sunday and anyother days i should go.well anyways thats just my 2 cents.
- 1,190
A 1999 British survey of 103 Roman Catholic priests, Anglican priests, and Protestant ministers/pastors found that about 25% do not believe the Virgin Birth. Yet, 97% of the same group do not believe the world was created in 6 days, and 80% do not believe in the literal existance of Adam and Eve.
thought those were some pretty interesting statistics
thought those were some pretty interesting statistics
- 10,687
- Everywhere
- 12,993
- USA! USA!
Atheism.
There is no God.
End.
There is no God.
End.
Well, I think it's obvious that there is some degree of evolution. Take bacteria in a lab. Also, you can look at people in high elevations. They have bigger lungs. I'm pretty sure that even if you take a child of two people from high elevations the kid will have larger-than-average lungs even if he lives at sea level. But I think that there was a point where, when humans were created, that God started to put in souls. That's when humans came about.
Yes I believe that there is a Trinity. Father, Son, and Holy Spirit.
And I think that it's likely that there are extraterrestrials.
I'm Roman Catholic.
Yes I believe that there is a Trinity. Father, Son, and Holy Spirit.
And I think that it's likely that there are extraterrestrials.
I'm Roman Catholic.
- 1,190
MadSci Network: Astronomy
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Re: Why do scientist think that God did not create the world and it was as bang
Date: Fri Sep 21 13:11:38 2001
Posted By: Nicolle Zellner, Grad student, Studies of the Origin of Life/Astrobiology, Rensselaer Polytechnic Institute
Area of science: Astronomy
ID: 997722050.As
--------------------------------------------------------------------------------
Message:
Actually, the world (the Earth) was not created by the Big Bang---the Universe was. Essentially, you're asking 2 questions: How was the Earth created? and why do we think the Universe started as the result of a "big bang"? I'll answer the 2nd question first.
The Big Bang
Light and substance are all around us and must have come from some source. Physics and math tell us that particles interact with each other to form other particles and by watching these particles, we can begin to understand from where they came. In the case of the evolution of the Universe, the most important interaction is gravity. Our modern understanding of gravity is described by Einstein's General Theory of Relativity. After his publication of it in 1915 people began to study it intently.
In 1927 Georges Lemaître (a Catholic priest and astrophysicist) published a description of the Universe's evolution, based on the General Theory of Relativity, that forms the basis of the modern model: Billions of years ago, all the material that we can see in the Universe had been in a single place. Further observations by Edwin Hubble in the late 1920s and 1930s showed that all the galaxies in the Universe are moving away from each other, implying that all "creation" really had once been in the same place then flew outward(1). In the 1940s, Ralph Alpher and his colleagues theorized that if there was a Big Bang, there should still be some evidence in the form of low-temperature radiation(2). In 1965, Arno Penzias and Robert Wilson detected that background radiation (static, if you will) and found that it permeated among all the galaxies. The temperature of this radiation (i.e., the temperature of the Universe) is what one predicts it would be if the Universe had once been superheated but has cooled as it expanded. This discovery was key in killing off a competing theory at the time, the Steady State Theory (that predicted that the Universe had always existed and could not explain this background radiation). Today, the Big Bang theory(1) is the only theory that can explain all of these data (and others not discussed here). Current thoughts are that the Big Bang happened between 10 and 15 billion years ago.
However, some theologians, versed in teaching about God, still find the idea of a "Big Bang" hard to believe, even though scientific evidence is supporting it. In an effort to reconcile science and religion, experts from both fields meet to discuss these issues(1). The group that sponsors these meetings(3) is the Center for Theology and the Natural Sciences.
For more reading on the idea of the Big Bang, check out The Whole Shebang by Timothy Ferris (Simon and Schuster Publishing, 1997). He touches on the topic of religion as well.
Formation of Earth
Once all the particles were created by the Big Bang, they began to interact with each other. Eventually (about 4.5 billion years ago), the particles in this part of the Milky Way galaxy collapsed into giant balls of dirt and gas that started revolving around our Sun(4). One reason we think that this happened here is because we can see planets forming around stars in other parts of the Galaxy(5). Physics and math tell us that what happens there probably happened here.
While it was once thought (and some still think[6]) that the Earth is only a few thousand years old, geology (fossils) and chemistry (radioactive decay of elements) tell us that Earth is about 4.5 billion years old. Fossils that can be dated at millions of years old have been found in rock formations, and there is evidence that life was around as long as 3.8 billion years ago(7,8). We can date the ages of rocks on Earth because of the radioactive decay of elements in the rocks. Radiometric dating works because of the natural instability of the nuclei of radioactive elements. When the nuclei decay, they break apart into simpler nuclei. With a large number of radioactive atoms, you can determine the rate of disintegration and thus infer the age. Uranium-238 decaying into lead-206 is a good example of this process(9). Finally, meteorites found on Earth have been dated to ages around 4.5 billion years(4). Since it's thought that almost everything in the Solar System formed at the same time, the age of the Earth should be that of the meteorites.
Scientific evidence, then, supports both the idea that the Big Bang formed our Universe and the idea that Earth was formed when dust and gas collapsed around our Sun. Philosophical questions as to why conditions were such that these processes occurred will always be around and will always, more than likely, remain unanswered.
References
US News and World Report, 1998 July 20, "What Came Before Creation?", pg. 44-52. This article can also be found at the US News and World Report web archive.
Alpher & Herman, 1948, "Evolution of the Universe", Nature, vol. 162, pg. 774--775.
There is a sidebar in the US New and World Report article about scientists and theologians discovering common ground (pg. 52).
Moons and Planets, 4th Edition, William K. Hartmann, Wadsworth Publishing, 1999.
For examples, see pictures of star-forming and planet-forming regions taken by the Hubble Space Telescope.
This "debate" rages on the Internet. pathlights.com attempts to discount the scientific evidence, but a more accurate assessment of the scientific evidence is at the talk.origins archive.
Mojzsis, S. J., Arrhenius, G., McKeegan, K. D., Harrison, T. M., Nutman, A. P., & Friend, C. R. L. 1996, "Evidence for Life on Earth Before 3,8000 Million Years Ago", Nature, vol. 384, pg 55-59.
Schopf, J. W. 1993, "Microfossils of the Early Archean Apex Chert: New Evidence of the Antiquity of Life", Science, vol. 260, pg 640-646.
Introductory Astronomy and Astrophysics, 3rd Edition, Zeilik, Gregory, & Smith, Saunders College Publishing, 1992.
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Re: Why do scientist think that God did not create the world and it was as bang
Date: Fri Sep 21 13:11:38 2001
Posted By: Nicolle Zellner, Grad student, Studies of the Origin of Life/Astrobiology, Rensselaer Polytechnic Institute
Area of science: Astronomy
ID: 997722050.As
--------------------------------------------------------------------------------
Message:
Actually, the world (the Earth) was not created by the Big Bang---the Universe was. Essentially, you're asking 2 questions: How was the Earth created? and why do we think the Universe started as the result of a "big bang"? I'll answer the 2nd question first.
The Big Bang
Light and substance are all around us and must have come from some source. Physics and math tell us that particles interact with each other to form other particles and by watching these particles, we can begin to understand from where they came. In the case of the evolution of the Universe, the most important interaction is gravity. Our modern understanding of gravity is described by Einstein's General Theory of Relativity. After his publication of it in 1915 people began to study it intently.
In 1927 Georges Lemaître (a Catholic priest and astrophysicist) published a description of the Universe's evolution, based on the General Theory of Relativity, that forms the basis of the modern model: Billions of years ago, all the material that we can see in the Universe had been in a single place. Further observations by Edwin Hubble in the late 1920s and 1930s showed that all the galaxies in the Universe are moving away from each other, implying that all "creation" really had once been in the same place then flew outward(1). In the 1940s, Ralph Alpher and his colleagues theorized that if there was a Big Bang, there should still be some evidence in the form of low-temperature radiation(2). In 1965, Arno Penzias and Robert Wilson detected that background radiation (static, if you will) and found that it permeated among all the galaxies. The temperature of this radiation (i.e., the temperature of the Universe) is what one predicts it would be if the Universe had once been superheated but has cooled as it expanded. This discovery was key in killing off a competing theory at the time, the Steady State Theory (that predicted that the Universe had always existed and could not explain this background radiation). Today, the Big Bang theory(1) is the only theory that can explain all of these data (and others not discussed here). Current thoughts are that the Big Bang happened between 10 and 15 billion years ago.
However, some theologians, versed in teaching about God, still find the idea of a "Big Bang" hard to believe, even though scientific evidence is supporting it. In an effort to reconcile science and religion, experts from both fields meet to discuss these issues(1). The group that sponsors these meetings(3) is the Center for Theology and the Natural Sciences.
For more reading on the idea of the Big Bang, check out The Whole Shebang by Timothy Ferris (Simon and Schuster Publishing, 1997). He touches on the topic of religion as well.
Formation of Earth
Once all the particles were created by the Big Bang, they began to interact with each other. Eventually (about 4.5 billion years ago), the particles in this part of the Milky Way galaxy collapsed into giant balls of dirt and gas that started revolving around our Sun(4). One reason we think that this happened here is because we can see planets forming around stars in other parts of the Galaxy(5). Physics and math tell us that what happens there probably happened here.
While it was once thought (and some still think[6]) that the Earth is only a few thousand years old, geology (fossils) and chemistry (radioactive decay of elements) tell us that Earth is about 4.5 billion years old. Fossils that can be dated at millions of years old have been found in rock formations, and there is evidence that life was around as long as 3.8 billion years ago(7,8). We can date the ages of rocks on Earth because of the radioactive decay of elements in the rocks. Radiometric dating works because of the natural instability of the nuclei of radioactive elements. When the nuclei decay, they break apart into simpler nuclei. With a large number of radioactive atoms, you can determine the rate of disintegration and thus infer the age. Uranium-238 decaying into lead-206 is a good example of this process(9). Finally, meteorites found on Earth have been dated to ages around 4.5 billion years(4). Since it's thought that almost everything in the Solar System formed at the same time, the age of the Earth should be that of the meteorites.
Scientific evidence, then, supports both the idea that the Big Bang formed our Universe and the idea that Earth was formed when dust and gas collapsed around our Sun. Philosophical questions as to why conditions were such that these processes occurred will always be around and will always, more than likely, remain unanswered.
References
US News and World Report, 1998 July 20, "What Came Before Creation?", pg. 44-52. This article can also be found at the US News and World Report web archive.
Alpher & Herman, 1948, "Evolution of the Universe", Nature, vol. 162, pg. 774--775.
There is a sidebar in the US New and World Report article about scientists and theologians discovering common ground (pg. 52).
Moons and Planets, 4th Edition, William K. Hartmann, Wadsworth Publishing, 1999.
For examples, see pictures of star-forming and planet-forming regions taken by the Hubble Space Telescope.
This "debate" rages on the Internet. pathlights.com attempts to discount the scientific evidence, but a more accurate assessment of the scientific evidence is at the talk.origins archive.
Mojzsis, S. J., Arrhenius, G., McKeegan, K. D., Harrison, T. M., Nutman, A. P., & Friend, C. R. L. 1996, "Evidence for Life on Earth Before 3,8000 Million Years Ago", Nature, vol. 384, pg 55-59.
Schopf, J. W. 1993, "Microfossils of the Early Archean Apex Chert: New Evidence of the Antiquity of Life", Science, vol. 260, pg 640-646.
Introductory Astronomy and Astrophysics, 3rd Edition, Zeilik, Gregory, & Smith, Saunders College Publishing, 1992.
--------------------------------------------------------------------------------
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- 10,687
- Everywhere
Ok, I've got another interesting thought. This is backing the "God watched over the evolution and progression of Earth's existance" belifes.
Hey, there's another good one. Why did a single cell decide to split? What the heck caused that? "Well, I was on my way to school one day and thought, 'I've always wanted a twin brother', so -poof- I made one." Ha ha!
Once again, I'm not arguing one way or the other, it's just something to think about. Just discussing points for the sake of something to do (:
~LoudMusic
Eddie brings up a good point. Translation, "Ok, so maybe I evolved from sea creatures ... but how did I get emotions like love and hate along the way?" I don't really see a way that emotions could evolve into existance. The theory of Evolution (on the grand scale) is there to support (and is supported by) the -fact- that animals are willed to survive, and adapt to their soroundings to better fullfill the need to survive. How do emotions play into that? And were do they get this will to survive in the first place, isn't that a pre-programmed emotion of its own? Something/someone had to put that desire in place in order for the whole experience to exist. Otherwise there would have been no desire for the first amebia to reproduce.
Hey, there's another good one. Why did a single cell decide to split? What the heck caused that? "Well, I was on my way to school one day and thought, 'I've always wanted a twin brother', so -poof- I made one." Ha ha!
Once again, I'm not arguing one way or the other, it's just something to think about. Just discussing points for the sake of something to do (:
~LoudMusic
- 687
Just a simple comment I am going to put here
God is God ..there are churches with people who think they are godly dont get the 2 mixed up
God is the truth people get it very mixed up and put there own views and ideas
the only answer to all your questions is is the bible if you want a truthfull answer seek and you shall find
read it and read it again the answer to all questions are there if you havent found the answer to your question you havent read it
God is there waiting for you to find him seek and you find how in the word read it
my final quote on this topic is from 2 Timothy 23-26
(23) Dont have anything to do with foolish and stupid arguments because you know they produce quarrells
(24) and the Lords servant must not quarrel instead he must be kind to everyone able to teach not resentful
(25) Those that oppose him he must gently instruct in the hope that God will grant them repentance leading them to a knowledge of the truth
(26) and that they will come to there senses and escape from the trap of the devil who has taken them captive to do his will
THE END
God is God ..there are churches with people who think they are godly dont get the 2 mixed up
God is the truth people get it very mixed up and put there own views and ideas
the only answer to all your questions is is the bible if you want a truthfull answer seek and you shall find
read it and read it again the answer to all questions are there if you havent found the answer to your question you havent read it
God is there waiting for you to find him seek and you find how in the word read it
my final quote on this topic is from 2 Timothy 23-26
(23) Dont have anything to do with foolish and stupid arguments because you know they produce quarrells
(24) and the Lords servant must not quarrel instead he must be kind to everyone able to teach not resentful
(25) Those that oppose him he must gently instruct in the hope that God will grant them repentance leading them to a knowledge of the truth
(26) and that they will come to there senses and escape from the trap of the devil who has taken them captive to do his will
THE END
- 10,687
- Everywhere
What about 'love'? I think it is easily argued that there was a time when humans did not love or laugh.
Here's some humor while staying on topic. I could tell when my cat was embarrised. When he would jump from something high in the house and not exactly "stick the landing", he would look around the room to see who noticed and if I was smiling at him he would hang his head and wander off. There were also times I remember him farting (man they stunk!) and when I'd look at him from across the room, he'd roll over so he couldn't see me stairing at him - much like a child playing hide and seek ... "I can't see you so you can't see me, right"
Is embarrasment an emotion? I feel strongly that my cat, and many other animals, have been embarrised by their actions, or missed actions ...
Anyway, I thought the look on my cat's face and his reaction to being 'caught' was quite humorous.
~LoudMusic
- 1,190
yes, you thought it was quite humorous ....the cat was embarrassed (an emotion) but didn't think it was funny .....if a dog sees a bird fly into a window, he doesn't think it's funny ......i forget which part of the brain is responsible for our interpretation of humour but this particular part is lacking in other animal's brains
- 10,687
- Everywhere
Yeah, the ballance of "good and evil" ... why there is life here and no where else within known range of Space ... strange things that seem to sort themselves out with little human intervention ...
I have lots of fun sci-fi 'theories' ... maybe 'possible story plots' would be better terminology.
Start with defining 'God' for Science Fiction purposes: The omnipotent power that controls life on Earth. No more definition is required, it is fully open to suggestion. It is not a single being, it is not 'everything', it is a force in the Universe (whoa ... StarWars referance there ...)
- What we refer to as God is actually an organization of scientists from a distant planet that created life on Earth as a scientific experiment. That one is my favorite, and was actually already used in a movie ... forget the name.
- Same as above, but more that life as we know it was/is a successful project to populate the Universe with 'organic AI quantum computers'. Originally there was one planet with intelligent life that came to realize they had the power to 'populate the Universe' and make it a more fun place to live (: They sent out a pod with instructions to create life on a planet with the goal to repleat the process as soon as the knowledge was achieved. Thus populating the Universe with organisms that wish to populate the Universe. It's a big place after all ... this could take some time (:
- God was/is meerly a story to enforce morals in humanity. The Bible is the codebook of 'possitive living' - and that statement can't be argued, even in reality.
- We are but a simple simulation in someone's enormous computer. "Hey look Ralph, this node is coming up with ideas about how we created them. Ain't that the coolest?!"
Anyway ...
~LoudMusic
- 1,190
Loud, here is your answer to why a single cell decided to split .... the first part does not address your question but nevertheless is still interesting .....i hope you will read it although it is quite lengthy
MadSci Network: Evolution
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Re: How does a cell evolve from a single-cell to a multicellular organism??
Date: Thu May 10 14:10:20 2001
Posted By: Joseph E. Armstrong, Faculty, Botany, Illinois State University
Area of science: Evolution
ID: 989341859.Ev
--------------------------------------------------------------------------------
Message:
You've asked an interesting question, actually two questions, one about
the origin of multicellularity and another about differentiation during
development. Your basic information is correct. Prior to cell division,
genetic material is copied. As you probably know, the DNA molecule has
two complementary halves; each half acts as a template to form a new
complementary half. Mitosis is a process that separates the two identical
sets of chromosomes. Usually mitosis is coupled with cytokinesis, a
process that divides the cytoplasm producing two separate cells. Since
multicellular organisms arise from a single cell, every cell has exactly
the same genetic information.
It seems most logical to answer the last question first. First
multicellularity exists in a range of different forms. In some
multicellular organisms all cells are identical and therefore perform
similar functions. In other multicellular organisms cells may
differentiate into specialized forms for specialized functions. In simple
organisms, only occasional cells may have specialized functions. In
others virtually all cells may become specialized to form familiar tissues
and organs. But while all these specialized cells are genetically
identical, different sets of genes, different portions of these genetic
instructions, are being followed. The developmental process is how cells
obtain information about their "location" and what set of instructions to
follow. Developmental biology studies how genes are regulated, turned on
and turned off, as an organism develops from a single cell. It's sort of
like a map to a city. All maps are identical, but different people follow
different routes to arrive at different destinations.
Very simple organisms have much simpler genetic programs. Consider a very
simple organism, a filamentous algae. A filament is a chain of identical
cells, although some filamentous algae do produce specialized cells. The
developmental program, in descriptive language, says to a cell, divide at
right angles to your long axis. This set of instructions is simply
repeated to produce a filament. If a second set of instructions was
added, a more complex form could be produced. For example, every 10th
time, divide parallel to your long axis then return to dividing at right
angles. This will produce a branching filament. Obviously more complex
forms develop from the addition of new sets of instructions, which must be
derived from the instructions that already exist. In other words, you
wouldn't expect a whole new set of instructions to just magically appear;
you might however expect a new set of instructions that are just a little
different from some set of instructions the cell already has. And we know
how such differences happen, mutations during DNA duplication.
Now let's address your first question. How did multicellularity arise?
Obviously from a small change in the instructions on how to divide into
two separate cells, the most common form of asexual reproduction. If for
example you were to watch a large number of Chlamydomonas cell divide, you
will occasionally see a double cell resulting from a failure of
cytokinesis. Perhaps this happens because of some mutation that causes a
failure to separate. Most likely the failure will result in the early
death of the double cell. This is a form of natural selection and an
example of how it works, in this case by weeding out mutations. But
suppose the mutation only causes separation failure, say once every 20
divisions or so. Since it works OK 19 out of 20 times, the mutated
instructions survive in the population even if the one of 20 dies. But
how could this become the regular case? If for some reason the double
cell found itself at an advantage, where it thrived instead of died, then
natural selection would be reversed to favor the mutation. Now I have no
idea about what might cause selection for a double cell that could lead to
multiple celled colonies and finally a magnificent organism like Volvox.
However, let's consider another example, a very simple seaweed, a single
celled algae anchored to a rock. Space is very limited on something like
a rock, so a larger size would allow this simple seaweed to compete better
for space and therefore light. So maybe it spreads out broadly, and this
works fine, until a different simple seaweed moves into the adjacent
space. Rather than have a short, broad cell, the new seaweed produces a
tall, slender cell that shades the short, broad cell, so the tall slender
cell is a better competitor for light under these conditions. Maybe a
third even taller seaweed arrives, but this competitive race will end
because there is a size limitation on single cells for both functional
reasons (cells must maintain a functional volume to surface area) and
structural reasons (big water balloons break easier than small water
balloons). If one of these single celled seaweeds had a mutation to its
genetic program for dividing and failing separate every 20th time, similar
to the one described above, then the production of a filament would be of
real competive advantage allowing an even bigger size via
multicellularity. So that's the basic answer. What was originally a
mistake in the genetic instructions to divide and separate became
instructions for making a simple multicellular organism (divide the cell,
but don't separate), and for some reason, in this case compeition for
light, the multicellular condition was an advantage.
This is how evolution works. A random process, mutation, causes variants,
many of which aren't functional at all. But some variants exist.
Changing environmental conditions select among variants, favoring some and
not others. Favored sets of instructions, even altered ones, become a
part of the organism's genetic instructions. Complex sets of
developmental instructions represent an accumulation of successful
mistakes.
Again think of the map analogy. You learn a new route to a new location
by retracing part of an old route and adding some new instructions to it.
Where's the new Thai restaurant (I'm always hoping)? Well, you know how
to get to the grease-burger palace? Well, rather than turning right by
the school, just go one block further and turn right. I found it by
accidentally missing the turn. And then you discover you like Thai food
so much, you never return to the burger palace. So now the instructions
have become the route to phad thai not to fries. Where's the bicycle shop
where you got the cool recumbent bike that replaced your gas guzzler
(still always hoping)? Well, you know how to get to Bangkok Palace? See
how things develop?
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MadSci Network: Evolution
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Re: How does a cell evolve from a single-cell to a multicellular organism??
Date: Thu May 10 14:10:20 2001
Posted By: Joseph E. Armstrong, Faculty, Botany, Illinois State University
Area of science: Evolution
ID: 989341859.Ev
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Message:
You've asked an interesting question, actually two questions, one about
the origin of multicellularity and another about differentiation during
development. Your basic information is correct. Prior to cell division,
genetic material is copied. As you probably know, the DNA molecule has
two complementary halves; each half acts as a template to form a new
complementary half. Mitosis is a process that separates the two identical
sets of chromosomes. Usually mitosis is coupled with cytokinesis, a
process that divides the cytoplasm producing two separate cells. Since
multicellular organisms arise from a single cell, every cell has exactly
the same genetic information.
It seems most logical to answer the last question first. First
multicellularity exists in a range of different forms. In some
multicellular organisms all cells are identical and therefore perform
similar functions. In other multicellular organisms cells may
differentiate into specialized forms for specialized functions. In simple
organisms, only occasional cells may have specialized functions. In
others virtually all cells may become specialized to form familiar tissues
and organs. But while all these specialized cells are genetically
identical, different sets of genes, different portions of these genetic
instructions, are being followed. The developmental process is how cells
obtain information about their "location" and what set of instructions to
follow. Developmental biology studies how genes are regulated, turned on
and turned off, as an organism develops from a single cell. It's sort of
like a map to a city. All maps are identical, but different people follow
different routes to arrive at different destinations.
Very simple organisms have much simpler genetic programs. Consider a very
simple organism, a filamentous algae. A filament is a chain of identical
cells, although some filamentous algae do produce specialized cells. The
developmental program, in descriptive language, says to a cell, divide at
right angles to your long axis. This set of instructions is simply
repeated to produce a filament. If a second set of instructions was
added, a more complex form could be produced. For example, every 10th
time, divide parallel to your long axis then return to dividing at right
angles. This will produce a branching filament. Obviously more complex
forms develop from the addition of new sets of instructions, which must be
derived from the instructions that already exist. In other words, you
wouldn't expect a whole new set of instructions to just magically appear;
you might however expect a new set of instructions that are just a little
different from some set of instructions the cell already has. And we know
how such differences happen, mutations during DNA duplication.
Now let's address your first question. How did multicellularity arise?
Obviously from a small change in the instructions on how to divide into
two separate cells, the most common form of asexual reproduction. If for
example you were to watch a large number of Chlamydomonas cell divide, you
will occasionally see a double cell resulting from a failure of
cytokinesis. Perhaps this happens because of some mutation that causes a
failure to separate. Most likely the failure will result in the early
death of the double cell. This is a form of natural selection and an
example of how it works, in this case by weeding out mutations. But
suppose the mutation only causes separation failure, say once every 20
divisions or so. Since it works OK 19 out of 20 times, the mutated
instructions survive in the population even if the one of 20 dies. But
how could this become the regular case? If for some reason the double
cell found itself at an advantage, where it thrived instead of died, then
natural selection would be reversed to favor the mutation. Now I have no
idea about what might cause selection for a double cell that could lead to
multiple celled colonies and finally a magnificent organism like Volvox.
However, let's consider another example, a very simple seaweed, a single
celled algae anchored to a rock. Space is very limited on something like
a rock, so a larger size would allow this simple seaweed to compete better
for space and therefore light. So maybe it spreads out broadly, and this
works fine, until a different simple seaweed moves into the adjacent
space. Rather than have a short, broad cell, the new seaweed produces a
tall, slender cell that shades the short, broad cell, so the tall slender
cell is a better competitor for light under these conditions. Maybe a
third even taller seaweed arrives, but this competitive race will end
because there is a size limitation on single cells for both functional
reasons (cells must maintain a functional volume to surface area) and
structural reasons (big water balloons break easier than small water
balloons). If one of these single celled seaweeds had a mutation to its
genetic program for dividing and failing separate every 20th time, similar
to the one described above, then the production of a filament would be of
real competive advantage allowing an even bigger size via
multicellularity. So that's the basic answer. What was originally a
mistake in the genetic instructions to divide and separate became
instructions for making a simple multicellular organism (divide the cell,
but don't separate), and for some reason, in this case compeition for
light, the multicellular condition was an advantage.
This is how evolution works. A random process, mutation, causes variants,
many of which aren't functional at all. But some variants exist.
Changing environmental conditions select among variants, favoring some and
not others. Favored sets of instructions, even altered ones, become a
part of the organism's genetic instructions. Complex sets of
developmental instructions represent an accumulation of successful
mistakes.
Again think of the map analogy. You learn a new route to a new location
by retracing part of an old route and adding some new instructions to it.
Where's the new Thai restaurant (I'm always hoping)? Well, you know how
to get to the grease-burger palace? Well, rather than turning right by
the school, just go one block further and turn right. I found it by
accidentally missing the turn. And then you discover you like Thai food
so much, you never return to the burger palace. So now the instructions
have become the route to phad thai not to fries. Where's the bicycle shop
where you got the cool recumbent bike that replaced your gas guzzler
(still always hoping)? Well, you know how to get to Bangkok Palace? See
how things develop?
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this is how most of me sees things but there's also a part of me who can't throw it all out the window ......i'm a Roman Catholic and believe my religion has had a considerable influence on how i was shaped as a person ....i'm glad i was raised this way but a modern day understanding of "everything" has me questioning my faith recently ......when i was 6 or even 10, i thought that the world (for example) was created by God in 7 days (that was the only possible explanation of Creation) ......but all of my knowledge gained through science and even geography courses so far in my academic career has proved that my early understanding of "things" was not really correct ......but i'm not going to reject the existance of God .....i couldn't do that .....nobody could .....i still think the Bible is the greatest book ever and will always be
funny you should mention the balance of "good Vs. evil" because i consider myself the perfect balance
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