Evolution/abiogenesis: Don't Understand? Ask Me.
Apos
Join Date: 2003-06-14 Member: 17369Members, Constellation
Join Date: 2003-06-14 Member: 17369Members, Constellation
in Discussions
<div class="IPBDescription">Debates welcome, but only on facts</div> This sort of thread has seemed successful in other venues, so I thought I'd try it here. Basically, I'd like to present myself as available to discuss or debate why darwinian evolution is central biology and is rightly presented as fact in science classes, and why abiogenesis (the spontaneous natural appearance of life on this planet) is considered a plausible and reasonable line of study (even though there is no hard and fast theory as of yet). I'll be happy to answer sincere questions (something about evolution you don't understand? Ask!), and I'll be happy to debate both theory and evidence.
In doing so, I'll be defending thee well established scientific principles, the first two related to evolution, and the last related to abiogenesis:
1) The mechanism of natural selection can increase information within gene pools, building functionality that seems thoughtfully designed, but was in fact thoughtlessly hit upon.
2) All known life on earth is descended through common ancestry. And yes, that means that your ten billionth grandmother or so was something like a bacteria. You and a tree are cousins... albiet VERY distant cousins.
3) Abiogenesis is plausible. No one knows what the EXACT mechanism was that began life on earth: what sort of replicator first appeared and how it developed, but the idea of it doing so doesn't contravene any scientific laws, and it seems to fit most of the basic facts about what the early earth was like, how the chemistry roughly might have worked, and what we know of early lifeforms.
I should note that, per board rules, I'm not going to entertain any direct discussion over religion here. Religious beliefs are up to the believer, and the fact is there are religious believers who both reject AND accept either evolution, the possibility of abiogenesis, or both. So religion is really a moot issue: proving evolution and the plausibility of abiogenesis doesn't refute god or religion.
On the other hand, I'll be happy to field complaints from the Intelligent Design crowd, who are anyway usually happy not to show their theistic colors.
Fire away!
In doing so, I'll be defending thee well established scientific principles, the first two related to evolution, and the last related to abiogenesis:
1) The mechanism of natural selection can increase information within gene pools, building functionality that seems thoughtfully designed, but was in fact thoughtlessly hit upon.
2) All known life on earth is descended through common ancestry. And yes, that means that your ten billionth grandmother or so was something like a bacteria. You and a tree are cousins... albiet VERY distant cousins.
3) Abiogenesis is plausible. No one knows what the EXACT mechanism was that began life on earth: what sort of replicator first appeared and how it developed, but the idea of it doing so doesn't contravene any scientific laws, and it seems to fit most of the basic facts about what the early earth was like, how the chemistry roughly might have worked, and what we know of early lifeforms.
I should note that, per board rules, I'm not going to entertain any direct discussion over religion here. Religious beliefs are up to the believer, and the fact is there are religious believers who both reject AND accept either evolution, the possibility of abiogenesis, or both. So religion is really a moot issue: proving evolution and the plausibility of abiogenesis doesn't refute god or religion.
On the other hand, I'll be happy to field complaints from the Intelligent Design crowd, who are anyway usually happy not to show their theistic colors.
Fire away!
Comments
i say it's even possible that while life appeared on earth through abiogenesis, that the entity that brought life to earth allowed it to evolve elsewhere from more primitive life prior to bringing them to earth to continue evolve here
<a href='http://www.genarts.com/karl/panspermia.html' target='_blank'>http://www.genarts.com/karl/panspermia.html</a>
The problem with all such theories is that, first of all, there is little evidence for them, and second of all, they still don't explain how that "seed" life came to be in the first place.
However, there is an element of known truth in these sorts of speculations, in that we know that meteorites and other cosmic bodies sometimes contain amino acids (perhaps because of various chemical processes that don't occur here on earth), which are the building blocks of life as we know it. It's possible that some amino acids were created here on earth, and other amino acids impacted and spread here from meteor/comet strikes, and then the two were both used in some abiogenetic process to form the first replicators. As with most things having to do with abiogenesis, the evidence is just too sketchy at present to say for sure.
The eyes in specific were actually one of the first complex structures that Darwin himself first discussed, which is why they are such paradigmatic examples.
Essentially, eyes evolved the same way as most everything else: by a series of gradual steps from one functional form to the next. In the case of eyes, it's likely that the structures started as very simple eyespots that responded to light (areas of a cell or special cells that react differently depending on how many photons hit them) and through millions of years various additional refinements were made over time. It's pretty easy to understand how both very simple lifeforms would already have certain parts more sensitive than others to light (since photons often affect chemistry, and life is a chemical machine) as well as why this might have proved to be an advantage if lifeforms happened to respond to light in non-random ways (for instance, light is a source of energy worth moving towards, or, later on in history light is a means by which others can see you: worth moving away from!), and many of the basic steps that the evolution of the mammalian eye could have taken were worked out even in Darwin's time. (you can see a picture of the basic progression here):
<a href='http://wiki.cotch.net/index.php/Eye_evolution' target='_blank'>http://wiki.cotch.net/index.php/Eye_evolution</a>
Of course, because eyes are very very soft parts indeed and rarely fossilize in any useful way, it's hard to know for certain exactly WHICH path the mammalian eye took to get to its present state.
However, eyes actually have evolved many different times, each time with a very different set of structures and "solutions" to the same sorts of functional problems (how to capture light and get information from that light about the surrounding environment). We thus have a very wide range of creatures alive today that demonstrate all sorts of different "eyes" from simple eyespots to the complex lensed eyes we have (our eyes aren't even close when it comes to the best eyes in the animal kingdom though). Especially once we have some sense of the exact pathways of common descent (i.e. who is our most distant ancestor and who is our most recent), we can work back, looking at modern animals, and get a sense of the basic progression of the eye.
I should note that evolution allows us to understand all sorts of interesting things about WHY our eyes have the characteristics they do. For instance, mammal eyes are actually pretty LOUSY at color vision compared to the rest of the animal kingdom. Why? Almost certainly because the recent ancestors mammals were all nocturnal, meaning that their eyesight spent a long time being adapted AWAY from good color vision to simply trying to catch and see by any light at all. Primates/humans, as it happens, have slightly better vision than most mammals, and surprisingly this is in part to a very simple set of genetic duplications and mutations.
It's also speculated that the reason all living things see in a very constrained spectrum of the available radiation is in part due to the fact that the original common ancestors of all creatures that later went on to develop more complex eyes originated the very very basic eye structures in the water, which filters out most of the wavelengths of light, leaving just the ones which then were seized upon by natural selection in the original watery environment. Because of the way evolution generally works, this basic setup was then adapted later on down the road, and became the norm even as animals started living out of the water.
More on that here:
<a href='http://www.karger.com/gazette/64/fernald/art_1_1.htm' target='_blank'>http://www.karger.com/gazette/64/fernald/art_1_1.htm</a>
The basic issue is that evolutionary theory allows us to make some pretty interesting inferences about WHY certain things about modern animals are the way that they are simply by knowing something about their evolutionary history. These inferences can then be further tested to see if they make sense with the available evidence. That's one reason that evolution has proven so powerful as a theory: because it seems to give us some very key insights into both the past history and the present function of organisms.
I'm not saying that it's wrong or anything, and I'm not saying that I believe God made us or whatever, i just can't wrap my head around it (and I do have a fairly ok understanding of evolution). I have a hard time imagining things so big (which is why the thought of an entire universe scares the hell out of me, how people like the good Stephen Hawking can hold things like that in their head amazes me).
The "time for everything to happen" question is a complicated one, most importantly because all sorts of different evolutionary changes happen at all sorts of different rates (for instance, it probably took a little less than a BILLION years of single-celled organisms before their colonies started to specialize and reproduce from a single DNA structure leading to multicelluar orgnaisms). What I can say at the start is that for some things, we can actually directly measure rates of what's called "mophological" change (litterally, the observable shape/form/structure of some feature) happening in nature. Take size, for instance: if we subject a guppy to an environment where it can benefit from growing larger than it once needed two, we can measure how fast the guppy increases in size, and then get a more generalizable "rate" of how fast such changes can occur.
And here's the surprising thing... the sorts of rates we measure for such changes are actually hundreds of times FASTER than would be necessary to account for even the fastest changes found in the fossil record (for instance, the size increase of horse-like creatures over time)! If anything, evolution needs to explain how natural selection slows down and reigns in explosive growth and change to a more stable and manageable rate (by punishing experiments that get out of control too quickly). That's a good start to explaining the current thinking on the "was there enough time" questions. The answer is: yes there certainly seemed to have been, and we have the fossil record: general samples of this change over time, to show for it.
Now, fingers.
The earliest tetrapods (i.e. four-limbed creatures: i.e. everything that walks the earth) actually had eight digits, if you can believe it. Amazingly, towards the end of the 20th century, we actually had some amazing fossil finds that actually preserved some soft parts (which is very very rare). On the fish side, we found a rhipidistian fish (which were already known to be ancestral to the first tetrapods, which were amphibians) with eight lobed "fingers" on its fins: just like the earliest tetrapods had! And on the amphibian/tetrapod side, we found a creature with internal gills: structures that no later tetrapod would retain but that would have allowed these early land-conquerers to alternatively breathe with either lungs or via gills!
Here's a reproduction of what we think one of these weirdo creatures looked like based on skeletal evidence and a bit a colorful paint:
<a href='http://chem.tufts.edu/science/evolution/04_Acan_flesh_reconstruct.jpg' target='_blank'>http://chem.tufts.edu/science/evolution/04...reconstruct.jpg</a>
Sorry, got carried away with myself. Fingers. Well, fingers are a complicated story, and like all such stories, they are not fully fleshed out. As I said, the earliest "fingers" were on those first tetrapods, and they were modified from bones in the lobes of rhipidistian fish (which were, obviously, lobed fish, not the ray finned kind to whcih we are more accustomed). As with any large structure, the evolution of something like fingers can be followed most easily via homology. In this case, we can see how the bones in the lobes of these "fish" got jerry-rigged into playing the role of fingers, which probably started out as nothing more impressive than simply outcroppings for friction so that creatures could drag themselves along on land.
Here's a pic of some of those similarities (note the basic overall bone structures are very much the same, though with some things missing or moved):
<a href='http://www.agiweb.org/news/evolution/forelimbs.html' target='_blank'>http://www.agiweb.org/news/evolution/forelimbs.html</a>
The earliest tetrapods actually still had skeletons designed to move in the same way that fish swim: moving from side to side. Their legs couldn't support their own weight, and were mostly useful for pushing off against things (to which the fingers just happened to be a further aid with, since they could latch onto even finer outcroppings). If you've ever seen a salamander walk, it would have been similar (how do we know how these creatures would have moved you might ask? Primarily by analyzing the physics of their skeletal structure).
Now fast forward a little bit, and the gradual change at least in the line we are concerned about (mammals) was that legs actually started to work like legs as we understand them: holding a body up. One of the major differences between reptiles and mammals (well, also reptiles and dinos) was having legs that stopped being splayed out to the side and actually supported the weight of the creature from beneath. Once we get to this point, thing get a little crazy with fingers, because suddenly all sorts of new terrains and movement styles open up as possibilities.
This is where fingers really start to take off, where toes and fingers are gained, lost, and modified in all sorts of crazy ways depending on what sort of lineage we are talking about (and realize that, actually, gaining or losing fingers is not always as complex as it sounds. Single duplications can add a finger, and single point mutations or deletions of sections of a gene can lose one. Even in humans, we see this happening all the time: currently useless sixth fingers are not uncommon: they are just lopped off at birth nowadays. Most structural changes to digits associated with losing or gaining them are actually a lot more complicated, but regulating the NUMBER of digits isn't quite as complicated as it might seem). Horses, for instance, "lost" all but one of their originally remaining three toes (though the remnants of those structures are actually still there in the horses' leg)
Why do WE have five, though? Well, right now the answer is an unsatisfying "because our ancestors had five fingers." In general, it makes sense that changing the number of fingers (whether adding or subtracting) wouldn't be all that favored by evolution unless there really was some sort of advantage to it. For horses, it makes a lot of sense considering the sorts of terrain they needed to operate on, and how they run. For more versatile mammals like us, we probably have an ancestral history more related to grasping than straight out running: our ancestors needs to be able to walk along branches and logs, and so forth. Our most recent anecestors, the primates, definately needed this functionality. That can sort of answer why we have five fingers instead of only one or two (though again, even among hooved animals, there are different numbers of toes!) though it's still not a completely satisfying picture. It may be that there is no hard and fast reason for five as a number compared to four or six: it's just that it needed to be in that range, so that's where it ended up in our distant ancestors, and afterwards there was really no evolutionary advantage to changing this pattern. Eight was never exactly an ideal number to begin with: as you can see from the fanciful reconstruction of the early tetrapod (actually, there is still some debate over whether we should call it a tetrapod or a fish, though such debates are, in the end, kind of silly since there is no hard and fast line), it's a pretty crowded hand! Not a lot of room for most sophisticated musculature or movement. So eight wasn't a particular stable number, and it didn't stay that way for very long once fingers had a chance to actually get out and do something on land. But it could be that if we "rewound" the history of life back to the early tetrapods and played it again, we'd see four fingers be the norm instead of five. Again, this is something we're going to need to do a lot more study on.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin--> I'm not saying that it's wrong or anything, and I'm not saying that I believe God made us or whatever, i just can't wrap my head around it (and I do have a fairly ok understanding of evolution). I have a hard time imagining things so big (which is why the thought of an entire universe scares the hell out of me, how people like the good Stephen Hawking can hold things like that in their head amazes me).<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
It's definately hard to concieve of. But I think part of that is less just the time it took, and more that we are taught to think of things in the world in terms of immutable <i>kinds</i>. THAT thing over there, you might say to yourself: THAT is a rabbit. Which is different from a rat. They're different! And the idea that these two things might be closely related seems bizarre (in part because many people wrongly think of one evolving from another. But no modern animal evolved from or into any other modern animal. Rather, they shared a common ancestor that may have been more like one or the other, or a similar to both). But actual life is messy and fuzzy (even among rabbits there are so many variations!) and very mutable generation to generation. This isn't weird, and it isn't even really outside the timescale of human imagination. It's just that, for convienience's sake, we are discontinuous thinkers that break things down into isolated units that are easier to deal with. Gradients and gradual sequences are very time consuming and troubling to think about.
The "time for everything to happen" question is a complicated one, most importantly because all sorts of different evolutionary changes happen at all sorts of different rates (for instance, it probably took a little less than a BILLION years of single-celled organisms before their colonies started to specialize and reproduce from a single DNA structure leading to multicelluar orgnaisms). What I can say at the start is that for some things, we can actually directly measure rates of what's called "mophological" change (litterally, the observable shape/form/structure of some feature) happening in nature. Take size, for instance: if we subject a guppy to an environment where it can benefit from growing larger than it once needed two, we can measure how fast the guppy increases in size, and then get a more generalizable "rate" of how fast such changes can occur.
And here's the surprising thing... the sorts of rates we measure for such changes are actually hundreds of times FASTER than would be necessary to account for even the fastest changes found in the fossil record (for instance, the size increase of horse-like creatures over time)! If anything, evolution needs to explain how natural selection slows down and reigns in explosive growth and change to a more stable and manageable rate (by punishing experiments that get out of control too quickly). That's a good start to explaining the current thinking on the "was there enough time" questions. The answer is: yes there certainly seemed to have been, and we have the fossil record: general samples of this change over time, to show for it.
Now, fingers.
The earliest tetrapods (i.e. four-limbed creatures: i.e. everything that walks the earth) actually had eight digits, if you can believe it. Amazingly, towards the end of the 20th century, we actually had some amazing fossil finds that actually preserved some soft parts (which is very very rare). On the fish side, we found a rhipidistian fish (which were already known to be ancestral to the first tetrapods, which were amphibians) with eight lobed "fingers" on its fins: just like the earliest tetrapods had! And on the amphibian/tetrapod side, we found a creature with internal gills: structures that no later tetrapod would retain but that would have allowed these early land-conquerers to alternatively breathe with either lungs or via gills!
Here's a reproduction of what we think one of these weirdo creatures looked like based on skeletal evidence and a bit a colorful paint:
<a href='http://chem.tufts.edu/science/evolution/04_Acan_flesh_reconstruct.jpg' target='_blank'>http://chem.tufts.edu/science/evolution/04...reconstruct.jpg</a>
Sorry, got carried away with myself. Fingers. Well, fingers are a complicated story, and like all such stories, they are not fully fleshed out. As I said, the earliest "fingers" were on those first tetrapods, and they were modified from bones in the lobes of rhipidistian fish (which were, obviously, lobed fish, not the ray finned kind to whcih we are more accustomed). As with any large structure, the evolution of something like fingers can be followed most easily via homology. In this case, we can see how the bones in the lobes of these "fish" got jerry-rigged into playing the role of fingers, which probably started out as nothing more impressive than simply outcroppings for friction so that creatures could drag themselves along on land.
Here's a pic of some of those similarities (note the basic overall bone structures are very much the same, though with some things missing or moved):
<a href='http://www.agiweb.org/news/evolution/forelimbs.html' target='_blank'>http://www.agiweb.org/news/evolution/forelimbs.html</a>
The earliest tetrapods actually still had skeletons designed to move in the same way that fish swim: moving from side to side. Their legs couldn't support their own weight, and were mostly useful for pushing off against things (to which the fingers just happened to be a further aid with, since they could latch onto even finer outcroppings). If you've ever seen a salamander walk, it would have been similar (how do we know how these creatures would have moved you might ask? Primarily by analyzing the physics of their skeletal structure).
Now fast forward a little bit, and the gradual change at least in the line we are concerned about (mammals) was that legs actually started to work like legs as we understand them: holding a body up. One of the major differences between reptiles and mammals (well, also reptiles and dinos) was having legs that stopped being splayed out to the side and actually supported the weight of the creature from beneath. Once we get to this point, thing get a little crazy with fingers, because suddenly all sorts of new terrains and movement styles open up as possibilities.
This is where fingers really start to take off, where toes and fingers are gained, lost, and modified in all sorts of crazy ways depending on what sort of lineage we are talking about (and realize that, actually, gaining or losing fingers is not always as complex as it sounds. Single duplications can add a finger, and single point mutations or deletions of sections of a gene can lose one. Even in humans, we see this happening all the time: currently useless sixth fingers are not uncommon: they are just lopped off at birth nowadays. Most structural changes to digits associated with losing or gaining them are actually a lot more complicated, but regulating the NUMBER of digits isn't quite as complicated as it might seem). Horses, for instance, "lost" all but one of their originally remaining three toes (though the remnants of those structures are actually still there in the horses' leg)
Why do WE have five, though? Well, right now the answer is an unsatisfying "because our ancestors had five fingers." In general, it makes sense that changing the number of fingers (whether adding or subtracting) wouldn't be all that favored by evolution unless there really was some sort of advantage to it. For horses, it makes a lot of sense considering the sorts of terrain they needed to operate on, and how they run. For more versatile mammals like us, we probably have an ancestral history more related to grasping than straight out running: our ancestors needs to be able to walk along branches and logs, and so forth. Our most recent anecestors, the primates, definately needed this functionality. That can sort of answer why we have five fingers instead of only one or two (though again, even among hooved animals, there are different numbers of toes!) though it's still not a completely satisfying picture. It may be that there is no hard and fast reason for five as a number compared to four or six: it's just that it needed to be in that range, so that's where it ended up in our distant ancestors, and afterwards there was really no evolutionary advantage to changing this pattern. Eight was never exactly an ideal number to begin with: as you can see from the fanciful reconstruction of the early tetrapod (actually, there is still some debate over whether we should call it a tetrapod or a fish, though such debates are, in the end, kind of silly since there is no hard and fast line), it's a pretty crowded hand! Not a lot of room for most sophisticated musculature or movement. So eight wasn't a particular stable number, and it didn't stay that way for very long once fingers had a chance to actually get out and do something on land. But it could be that if we "rewound" the history of life back to the early tetrapods and played it again, we'd see four fingers be the norm instead of five. Again, this is something we're going to need to do a lot more study on.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin--> I'm not saying that it's wrong or anything, and I'm not saying that I believe God made us or whatever, i just can't wrap my head around it (and I do have a fairly ok understanding of evolution). I have a hard time imagining things so big (which is why the thought of an entire universe scares the hell out of me, how people like the good Stephen Hawking can hold things like that in their head amazes me).<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
It's definately hard to concieve of. But I think part of that is less just the time it took, and more that we are taught to think of things in the world in terms of immutable <i>kinds</i>. THAT thing over there, you might say to yourself: THAT is a rabbit. Which is different from a rat. They're different! And the idea that these two things might be closely related seems bizarre (in part because many people wrongly think of one evolving from another. But no modern animal evolved from or into any other modern animal. Rather, they shared a common ancestor that may have been more like one or the other, or a similar to both). But actual life is messy and fuzzy (even among rabbits there are so many variations!) and very mutable generation to generation. This isn't weird, and it isn't even really outside the timescale of human imagination. It's just that, for convienience's sake, we are discontinuous thinkers that break things down into isolated units that are easier to deal with. Gradients and gradual sequences are very time consuming and troubling to think about. <!--QuoteEnd--> </td></tr></table><div class='postcolor'> <!--QuoteEEnd-->
You just hurt my brain.
Interesting read though <!--emo&:p--><img src='http://www.unknownworlds.com/forums/html/emoticons/tounge.gif' border='0' style='vertical-align:middle' alt='tounge.gif' /><!--endemo-->
A- why does junk food and unhealthy stuff taste so good while nutrious vegstables taste like crap? why would any creatures evolve to hate good things and love bad things?
B- if everyone evolves and what have you... why is it that humans are so diffrent from everything else? I mean why doesn't air bud evolve kids that can talk. and make a who new breed of crappy disney movies?
C- if the point of evolving is to pass on our genes and reproduce why did we evolve into higher level life forms? there's billions and billions of bacteria, but only a couple billion humans, why didn't we just evovle into some kind of super bacturium? like in NS? that'd be more effective if just getting numbers is what our genes want us to do.
D- looking at fossils to tell us about "missing links" doesn't seem like sound logic... what if an old man way back when just had really cronic back disorders, and when he turned into a fossil and we found it we say "look how he's all hunched over and looks funny, must be a half ape" I mean for reals.
E- how can you even consider carbon dating to be accurate? right now were just guessing that it is. how do we know that the C-14 goes away at a constant rate? that diffrent extremes in conditions don't effect the results. how do we even know that it works? who's been around for 1000's of years to see if it works? the idea's been around for a couple years and we just assume that its flawless? so how can you even guess how old anything is?
F- if were programmed to evolve why do things like "jimmy cricket" make us asks questions about cloning and stem cell research? why would people feel bad about killing homo's? or any handi-capped person for that matter. when a baby kangaroo is born it has to climb into the mothers pouch, if it falls trying to get in it'll die because the mother won't help it in. people say thats natural selection. so why don't we just kill all the weak people that are born if thats how were meant to be on a genetic level
G- if we were constantly evolving, how did anyone ever "make up" god and all that. why would someone say " I think I was made from dirt and my wife came from my rib" when your mom is a monkey?
H- how did marrige come about? no other creatures in the world get married. theres a dog in my neighboorhood that must have mated with at least 10 **** around. and he doesn't care? why has marrige existed for the entire existence of known history?
I- if you compared every fossil to every supernatural event... the scale would tip towards supernatural. how do you explain the millions of incidents that indicate that there are greater forces at work then just nature?
J- if Darwin was so sure about all this, why did he renounce his theries on his deathbed?
K- Why aren't all creatures asexual? whats the benefits of having to have a man and a women to make a baby?
B- if everyone evolves and what have you... why is it that humans are so diffrent from everything else? I mean why doesn't air bud evolve kids that can talk. and make a who new breed of crappy disney movies?
C- if the point of evolving is to pass on our genes and reproduce why did we evolve into higher level life forms? there's billions and billions of bacteria, but only a couple billion humans, why didn't we just evovle into some kind of super bacturium? like in NS? that'd be more effective if just getting numbers is what our genes want us to do.
D- looking at fossils to tell us about "missing links" doesn't seem like sound logic... what if an old man way back when just had really cronic back disorders, and when he turned into a fossil and we found it we say "look how he's all hunched over and looks funny, must be a half ape" I mean for reals.
E- how can you even consider carbon dating to be accurate? right now were just guessing that it is. how do we know that the C-14 goes away at a constant rate? that diffrent extremes in conditions don't effect the results. how do we even know that it works? who's been around for 1000's of years to see if it works? the idea's been around for a couple years and we just assume that its flawless? so how can you even guess how old anything is?
F- if were programmed to evolve why do things like "jimmy cricket" make us asks questions about cloning and stem cell research? why would people feel bad about killing homo's? or any handi-capped person for that matter. when a baby kangaroo is born it has to climb into the mothers pouch, if it falls trying to get in it'll die because the mother won't help it in. people say thats natural selection. so why don't we just kill all the weak people that are born if thats how were meant to be on a genetic level
G- if we were constantly evolving, how did anyone ever "make up" god and all that. why would someone say " I think I was made from dirt and my wife came from my rib" when your mom is a monkey?
H- how did marrige come about? no other creatures in the world get married. theres a dog in my neighboorhood that must have mated with at least 10 **** around. and he doesn't care? why has marrige existed for the entire existence of known history?
I- if you compared every fossil to every supernatural event... the scale would tip towards supernatural. how do you explain the millions of incidents that indicate that there are greater forces at work then just nature?
J- if Darwin was so sure about all this, why did he renounce his theries on his deathbed?
K- Why aren't all creatures asexual? whats the benefits of having to have a man and a women to make a baby? <!--QuoteEnd--> </td></tr></table><div class='postcolor'> <!--QuoteEEnd-->
Hell, I can answer these:
A- Because they are filled with sugar and fat, which is what we needed to survive in the wilderness barely a million years ago. They are so appealing because, in small quantities, the sugars are incredibly good for our body, so we evolved a strong desire to seek them out. That desire hasn't gone away yet, and it won't, until a majority of junk-food eaters drop dead.
B- Why are rabbits different from fish? Why is Sulfur different from Hydrogen? Humans just happen to be the only species capable of society, written language, and so forth. Air Budd can't automaticlly have speaking children because theres no need to. He can survive as he is, and there are no environmental reasons for him to change.
C- I can't be sure about this, but I think macroscopic (bigger than bacteria) life is kind of a fluke. Its short lived, evolves slowly, and is likely to become extinct. However, life trends towards complexity. If we had evolved into bacteria, we wouldn't be having this conversation.
D- Well, that is a possibility. But those are incredibly bad odds. If that old man had a back disease that long ago, he'd probably be long dead before he could even grow old, and let his spine become worse.
E- We know the C-14 decays at a constant rate because its A FACT. All unstable isotopes decay at a constant rate, which is called their "half-life". And we know it works because we can see that after any given amount of time, you're going to have less Carbon-14 then when you started. And the amount you lose is based on its half-life. Neptunium has a half-life of about three days, but we can determine its half life after even less than three hours. You don't need to be around the whole three days,
F- Because we have morals. You're talking about eugenics. And since this is a debate online, I have to bring Hitler into it. The Nazis supported and carried out eugenics programs. Eugenics is horrific, because we are people. We aren't animals. We think and we feel and we can't force someone to be sterilized because theres no reason to. The species isn't in danger of being wiped out due to bad genetics.
And FYI, those of us with a tendancy towards the same sex don't really like to be called "homos".
G- Because it doesn't work like that. The change in humans is so gradual, that you wouldn't notice. As for the "making up" god, I'll approach that carefully. In my opinion, its so people could feel safe "knowing" there is someone supernatural protecting them. And besides, they had no way of knowing about evolution, so they needed some way to explain their origins. Science wasn't too good back then.
H- Marriage came about because of society. Because we have complex emotions such as love, human culture decided to create an institution binding two people together. This prevents infidelity, which leads to jealousy, anger, and possibly murder. With a murder there is one less of a species, and thousands of years ago, losing one member of a tribe could mean the entire culture would die.
I- I'm not quite sure what you're reffering to.
J- I wasn't aware that he did this. But Kepler could have proclaimed that the planets were on the backs of turtles. Doesn't mean orbital dynamics aren't true.
K- The benifits are that there is a greater chance of change. With asexual cell division, each off-spring is exactly like its parent, with the exception of the occaisional mutation. With sexual reproduction, different genes are introduced, producing a new offspring, distinct from its parents. If these gene structures are better than the parent's, they organism will perform better, and benifit the species as a whole. Also, without the system we have, there would be no society. The most basic social group is the family, which is at the core of society. Asexual creatures don't have families. They have clones. Identical copies which are probably quite boring to talk to.
And if you don't "believe in evolution", what do you accept as fact, that has any scientific support?
Remember <a href='http://www.unknownworlds.com/forums/index.php?showtopic=86677&st=0' target='_blank'>this</a> thread? That explains your last question straight off the bat (J), and a few others, too. I'm not sure how you forgot the answer to A. so quickly.
<!--QuoteBegin-AvengerX+--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> (AvengerX)</td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->A- why does junk food and unhealthy stuff taste so good while nutrious vegstables taste like crap? why would any creatures evolve to hate good things and love bad things?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
<!--QuoteBegin-AvengerX from the Darwin thread+--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> (AvengerX from the Darwin thread)</td></tr><tr><td id='QUOTE'><!--QuoteEBegin--> sorry kids, but evolution is totally false... let me explain to you why.....
if we did evovle from single cell organisms and what not when we were being started. as we grew and developed we decided to evovle this thing called "taste" and we decided that for some reason... everything that "tastes" good will be nutritously bad, and that everything that "tastes" bad will be extremly healthy for us.... WHY WOULD ANY ORGANISM EVOLVE INTO SUCH A STUPID WAY LIKE THAT!@!!!!!!!! if we did evolve we'd have evovled taste pallets that craved spinach and carrots 24/7
there you have it morons.... evulution is totally false....
thank you<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
<!--QuoteBegin-sky from Darwin thread+--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> (sky from Darwin thread)</td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->Avenger, did it ever occur to you that maybe our diets were significantly different back then? Sugary foods are, for the most part, picky about where, when, and how they grow. As a result, sugar is rather rare, or at least it was where early humans and their ancestors were living. Sugar is, however, and excellent source of energy, especially when you tend to burn a lot of calories; for instance, if you're doing a lot of physical activity.
Therefore, sugar was actually desirable for humans to seek out and injest, because it represented a quick, simple burst of energy with basically no drawbacks because it wasn't eaten very often. The grains that are actually healthier for us in large quantities are what we evolved to eat a lot of; they aren't good for us because of random chance, they're good for us because our bodies are designed to eat a lot of it. Also, we didn't need whole wheat and such to taste "sweet" because we didn't have a choice in the manner; we ate the grain or we starved. Meat tastes good to most people because originally it was hard to come by; the whole hunting thing kinda made eating meat a tad trickier than it is today. Meat is also not good for us in large quantities, but we still need it.
Also note that children's taste buds "like" sugary foods more than adults, mirroring the greater amount of quick-burning energy that children need. Glucose is the only fuel that the brain uses, and it's very important that children with developing brains don't starve their minds of fuel; that could lead to stunted brain growth. Hence, it was actually more important for children to seek out the substance than adults, and this disparity is reflected in our tastes today.
Sugar is NOW looked on as "bad" for us because it's in nearly everything we eat, because we evolved taste buds that "like" it. Unfortunately (and this goes to prove that evolution doesn't necessarily work to more perfect organisms) evolution could not forsee that humans would eventually become so attatched to the sweet taste of sugar that they would specifically grow and make foods containing large quantities of it. Add to that the fact that an average human's life was becoming more sedentary which leads to slower metabolisms, and you have our sense of taste that used to seek out the "good" now seeking out the "bad". Of course, since natural selection has been displaced by social pressures and other factors for a good part of our species' history, our taste buds aren't changing any time soon.
Oh and, AvengerX, I have a nice quote for you: "The words you speak today should be soft and tender....for tomorrow you may have to eat them." Welcome to the Discussion forum, check your attitude at the door. <!--emo&:p--><img src='http://www.unknownworlds.com/forums/html/emoticons/tounge.gif' border='0' style='vertical-align:middle' alt='tounge.gif' /><!--endemo--> <!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
<!--QuoteBegin-AvengerX+--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> (AvengerX)</td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->E- how can you even consider carbon dating to be accurate? right now were just guessing that it is. how do we know that the C-14 goes away at a constant rate? that diffrent extremes in conditions don't effect the results. how do we even know that it works? who's been around for 1000's of years to see if it works? the idea's been around for a couple years and we just assume that its flawless? so how can you even guess how old anything is?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
<!--QuoteBegin-Apos+--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> (Apos)</td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->...And, as I said: fine, doubt that carbon dating works at a constant rate (actually, this is another tip-off: carbon dating isn't used for anything other than very very recent things because it has a very short half-life: different isotopes or different atoms are used for longer range dates). Why then does it happen to match up with other sorts of dating phenomenon, like tree rings or seafloor spreading or magnetic polarity reversals? How do you explain how all these methods, which each represent independant lines of figuring out the dates of things, all give the same answers?
There is a much more extensive discussion about how all these things fit together here:
<a href='http://forums.tolkienonline.com/viewtopic....1091aef7509f0dd' target='_blank'>http://forums.tolkienonline.com/viewtopic....1091aef7509f0dd</a><!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
Anyways heres a question:
Is any self-replicating compound, or even say a non-corporial thing such as an idea, subject to natural selection? And if so, why is it that we don't observe extremely different forms of "life" all the time? Do we simply not recognize it?
For example, when refering to ideas, there is this concept of meme. Memes supposedly act alot like a lifeform subject to the process of natural selection, the selection pressure in this case being mostly memorability. For isntance (and this isn't the best example) we have the term "pwned" in gaming culture. Now the word "pwned" all on its own doesn't make alot of sense, I mean, the laws that govern most of the english language certainly don't apply. What appears to have happened is that an idea "own" took on a new meaning in a new environment, and replaced the "o" with a "p", which was a preferable trait because its more funny (and thus more memorable). In a sense it evolved. There was a question in here somewhere, but I seem to have forgotten it, so reply with whatever comments you migh have on this ("skulkbait is a nutjob" is a likely possibility).
Anyway, on a similar line, are you familiar with the work of Thomas S. Ray? If so, you'll recall that the first digital lifeforms to evolve from Ray's original digital organism were parasitic, and that the adaptations from that point on were concentrated on immunity and um... anti-immunity? (you can tell I'm too tired for this).... Is it possble that the first organic replicators could have had a very similar "war", and furthermore, do these kinds of adaptation "wars" concentrating on one, or a very small group of, traits happen often in the animal kingdom?
Bleh. Sorry.
Does evolution explain some odd instinctual stuff? I seem to remember that at birth, a certain type of beetle knows that it has to dig its way up to the surface, etc. How does it know? Is it somehow preprogramed? Or is this outside of evolution's remit?
<!--QuoteEnd--> </td></tr></table><div class='postcolor'> <!--QuoteEEnd-->
I know where you're coming from, it seems like they keep using the same points over and over all the time doesn't it? It gets annoying fast, which is one of the reasons I'm thinking that Apos wants it as I said, so that he can deal with their questions without them being distracted by the arguments of others.
The key things it has to have for something like natural selection to apply are:
1) trait heredity (i.e. traits get passed down with reasonably good fidelity generation to generation)
2) trait variation (i.e. there is some mechanism by which traits change in all sorts of different small ways in different individuals)
3) differential reproductive/replicative success that's non-randomly related to particular traits
So self-replication is not quite enough. Fire self-replicates, for instance. But though it has tons of variation and differential success, it has no true trait heredity.
Ideas actually DO seem to fit the definition somewhat, and as you noted, the study of memes is being taken more and more seriously as a mechanism for cultural evolution. However, it's certainly not as easy to prove or track as biological evolution, and there are a number of questionable elements about just jumping ahead and saying that gene and meme evolution are the same process, different day.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->And if so, why is it that we don't observe extremely different forms of "life" all the time? Do we simply not recognize it?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
At least in terms of physical self-replicators, there are several reasons. First of all, self-replication, even though we don't know exactly what sort OUR life came from, actually is observed to some small extent in all sorts of different things (crystals, fire, prions, etc.). As I noted, however, that's not quite sufficient. As for the particular sorts of self-replicators that could lead to life, whether they are the same ones our life would have come from or not, it's likely that they would at least require being fairly complex organic compounds. And that's where we run into trouble, because the planet is, unlike in early times, currently covered in some of the best and most efficient devourers of organic compounds we know of: bacteria. In short, if any new life arose on this planet today, unless it were very very special already, it would be eaten!
There are also chemical reasons why the sorts of things that occured to start our form of life aren't as common on the planet today. The environment of the early earth had a number of environments conducive to, say, the creation of organic compounds like amino acids. Those environments are much scarcer today, mostly due to the fact that there is TONS of oxygen around today. We may think of oxygen as important for life, and it is. But that's because we've evolved to deal with some of its bigger threats to life: the fact that it is highly corrosive to the carbon compounds of which life is made (and would have been made). In short, too simple complex carbon compounds that form in nature today BURN in our oxygen-rich atmosphere, which stunts their potential. The atmosphere of the early earth would have had a lot less free oxygen than is around today, and a lot more places where it was even sheltered from what oxygen there was.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->If so, you'll recall that the first digital lifeforms to evolve from Ray's original digital organism were parasitic, and that the adaptations from that point on were concentrated on immunity and um... anti-immunity? (you can tell I'm too tired for this).... Is it possble that the first organic replicators could have had a very similar "war", and furthermore, do these kinds of adaptation "wars" concentrating on one, or a very small group of, traits happen often in the animal kingdom?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
It is definately possible, and yes, such wars happen very often in the animal kingdom (predator/prey) and indeed are credited with driving some of the most explosive evolutionary changes. Living things compete with each other, first of all with other living things that eat the same foods and try to make do with the same trades, and also with living things that make their livings in ways that damage or kill other living things.
As has been stated before, this is one is easy to explain. Evolution is a process that has no foresight. It could not "know" that homo sapiens would one day be so succesful in life that they could litterally get any foods they wanted mass produced and on demand. Evolution doesn't "know" anything. All it can work with are the present conditions, and those conditions, in which the taste buds and cravings of human beings were shaped, were characterized not by an abundance of simple sugars and fatty foods, but by a scarcity of them. Those cravings were formed in an environment in which those things were rare treats, and fantasitically good for you in the low doses that we could get them. But now that we can fill those cravings in ways natural selection could never have anticipated, we are dealing with the problem that we have fat storage systems and other body systems that also never anticipated having to deal with huge quantities of sugar or fat. They couldn't have anticipated it.
They can't anticipate any future event. Once you realize that, a lot of the questions about human beings or indeed any creature suddenly thrown into a new environment, start to make sense. And that's one of the powers of evolution as a theory: it makes sense of why things are the way they are.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->B- if everyone evolves and what have you... why is it that humans are so diffrent from everything else? I mean why doesn't air bud evolve kids that can talk. and make a who new breed of crappy disney movies?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
The answer is simply because, at least up until the recent past, there was no evolutionary advantage in it (not to mention that dogs would have a long long long way to go before their vocal cords or brains would be suited for complex language, and even now there's really no pressure to drive them in that direction, let alone several million years to make it happen). From our perspective, we humans seem unique. But the reality is that in terms of what _evolution_ cares about, we are neither anywhere near the most succesful animals (that would be insects, many times over) nor the most successful form of life (that would be bacteria). And in many ways, we are _unexceptonal_ compared to the rest of life. Only our nervous systems are truly impressively unique. But then, lots and lots of different features in the animal kingdom are impressively unique. We are particularly impressed with our large brains only in part because that's one of the things that large brains happen to do: be impressed with themselves. But in the long run, it may not be all that important.
Basically, you have to realize that what WE think might be cool is not necessarily any relevance to what selective pressures affect real creatures. And it is those selective pressures that actually shape what traits and capacities creatures have, not our wild fancies.
But... there is an exception. And that is the fact that our fancies CAN shape evolution in particular ways, and in fact have already done so. Take "Air Bud" for instance. You take for granted a lot of things about dogs being the way they are: but in fact dogs were bred to be the way they are! Via a process known as artificial selection, in the past few thousand years, we've bred dogs from wolves, and bred into them all sorts of traits that actually are quite remarkable. In addition to all the sorts of abilities and physical traits we've selected for, dogs can actually read and properly respond to human emotion. That's not quite talking, but that is what makes dogs like air bud capable of making crappy movies: the fact that they can appeal so well to human emotion. By doing the selecting in dog evolution (taking over from natural forces and pressures) humans have bred into dogs the traits necessary to be companions, be trainable, and so on.
Interestingly, as an experiment some scientists have been trying to domesticate foxes in the same way. And in only 45 years, they've already bred tame, human-lving foxes with more emotive and appealing faces as well as the ability to... read and respond to human emotion. And that's just in 45 years!
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->C- if the point of evolving is to pass on our genes and reproduce why did we evolve into higher level life forms? there's billions and billions of bacteria, but only a couple billion humans, why didn't we just evovle into some kind of super bacturium? like in NS? that'd be more effective if just getting numbers is what our genes want us to do.<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
Because there are many many different ways of making a good living. One of those ways, for instance, is eating other bacteria. Another might be banding together in colonies of bacteria. Yet another might be in some members of these colonies specializing. You can follow the logic from there. Basically, new trades of survival are constantly open, and living things are constantly rushing in to fill them. But that doesn't necessarily close off the usefulness of the old trades, which is why, as you note, bacteria haven't gone anywhere. It's just that over time, some genes have found success in coding for more and more complex survival machines to protect themselves and ensure their reproduction.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->D- looking at fossils to tell us about "missing links" doesn't seem like sound logic... what if an old man way back when just had really cronic back disorders, and when he turned into a fossil and we found it we say "look how he's all hunched over and looks funny, must be a half ape" I mean for reals.<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
While it's true that a single fossil might be decrepit, it's both very unlikely (in nature, weak or broken forms would have been weeded out very quickly and would have been much more rare) and not really a problem. First of all, there are all sort of studies and comparisons that can be done to tell if particular features are really from old age or disease or are instead the basic normal skeletal layout. Second of all, we normally find more than a single individual anyway. There are lots of "Lucy"'s now, for instance. The recent homo floresiensis find, a new and interesting one that appears to be a new species of tiny hominid, is being evaluated right now for these sorts of issues, as we speak, to figure out if he is really a new species or instead some sort of stunted example of a different species. Here's a brief discussion of the sorts of things that we can look at:
<a href='http://pharyngula.org/index/weblog/comments/homo_floresiensiss_brainigor_didnt_screw_up/' target='_blank'>http://pharyngula.org/index/weblog/comment...didnt_screw_up/</a>
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->E- how can you even consider carbon dating to be accurate? right now were just guessing that it is.<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
No: we can establish that it is. There are lots and lots of ways to do it.
One easy way is to use tree rings. Tree rings form one each year, and some trees are so old that they have year by year records going back hundreds of years. Even better, we can match up these rings with the rings of even older trees that might have died longer ago (but, say, were in the same fire towards the end of their life that the more recent tree was in at the start of its life, allowing us to link the two records). And when we date the carbon found wedged in between the rings, or from events that match up with what we know from the tree rings, what do we find? That the carbon method gives us the dating that is correct for what the tree rings tell us it should be!
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->how do we know that the C-14 goes away at a constant rate?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
First of all, because if it didn't have a relatively constant rate, then we'd be able to measure it in things like lake silt samples that record such things over time. C-14 actually _hasn't_ gone away at an exactly constant rate, which is why the method is calibrated by all sorts of natural checks like the one I described above. And you should know that C-14 isn't really used for anything much older than 45,000 years or so. We have other, much more powerful radioactive dating methods for older ages.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->F- if were programmed to evolve why do things like "jimmy cricket" make us asks questions about cloning and stem cell research? why would people feel bad about killing homo's? or any handi-capped person for that matter. when a baby kangaroo is born it has to climb into the mothers pouch, if it falls trying to get in it'll die because the mother won't help it in. people say thats natural selection. so why don't we just kill all the weak people that are born if thats how were meant to be on a genetic level<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
I don't really understand what you mean. Natural selection doesn't "want" us to do anything in particular: it is just a process, not a mind or an intention. There is no "meant" to be that comes from natural selection. It can certianly incline species to act a certain way, or it can incline them to act a different way: all depending on what makes sense for the suvival of particular genes. But those inclinations can prove disasterous if the particular environment in which they work well in changes.
In humans and many social animals, for instance, altruism is actually favored: humans do better when they gang up and collaborate. Does this mean that natural selection "means" us to be altruistic? No. It's just that our collaborating ancestors did better than their more independant cousins, and we are the result. What WE should do is up to us. Unlike most animals on the planet, we have minds that can figure things out and wills that can rebel or question our urges and habits and reflexes.
Equating homosexuality with a handicap isn't going to win you many friends around here.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->G- if we were constantly evolving, how did anyone ever "make up" god and all that. why would someone say " I think I was made from dirt and my wife came from my rib" when your mom is a monkey?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
Recorded human history is a very very recent innovation. Most likely early human cultures simply knew about the history of their ancestors a few steps back and no further, and they didn't understand much about the natural world. Many groups of humans wouldn't have even known what an ape was.
So in the abscence of any known history or science, developing particular religious ideas about their origins is not surprising at all.
And no ones mom was "a monkey" in the sense you mean: nowhere did one species give birth to a radically different species. It was much more gradual than that, taking hundreds of thousands of generations before there was much observable change. All of human history isn't even as old as our own species is!
Though everyone's mom is a monkey (well, an ape, really) in the sense biologists mean.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->H- how did marrige come about? no other creatures in the world get married. theres a dog in my neighboorhood that must have mated with at least 10 **** around. and he doesn't care? why has marrige existed for the entire existence of known history?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
Well, for one thing, it hasn't, certainly not in the form you are accustomed to thinking of. In fact, for the majority of known human history and in the majority of known human cultures, humans have had harems (one man rules over many conquests and stable females) rather than monogamous marriages. This past is reflected, amusingly enough, in the tiny relative size of our testicles. <!--emo&:)--><img src='http://www.unknownworlds.com/forums/html/emoticons/smile-fix.gif' border='0' style='vertical-align:middle' alt='smile-fix.gif' /><!--endemo-->
Marriage as we know it is a cultural development. Evolution doesn't explain it, nor should it have to, at least not directly.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->I- if you compared every fossil to every supernatural event... the scale would tip towards supernatural. how do you explain the millions of incidents that indicate that there are greater forces at work then just nature?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
I don't know what you are talking about. First of all, what does this have to do with evolution per se? Second of all, what supernatural events, and third of all, what would be the point of comparing the number of one to the other? I mean, the number of fossils doesn't mean anything that's relevant to anything. Fossilization is a rare, freak occurance, and we expect it to be such.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->J- if Darwin was so sure about all this, why did he renounce his theries on his deathbed?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
You couldn't possibly be asking this question when we had a whole thread discussing that this was a slanderous lie, right? I mean, even creationists like AiG don't use this lline anymore because of how dishonest and nasty it is. Regardless, even if Darwin had renounced his own theory (he didn't), it wouldn't make any difference at all. Evolution rests on the evidence, not on the opinions of this or that person.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->K- Why aren't all creatures asexual? whats the benefits of having to have a man and a women to make a baby?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
Some creatures are asexual. Almost all bacteria are. Some rotifers are. Some female flies can actually form children in their bodies that have children in THEIR bodies at the same time! Some creatures are sexual. Obviously there are advantages to be had for both ways, just as there are advantages to either flying or running on the ground. And that's misleading: there are so many different WAYS to be a sexual species, for sex to work, that it's mind boggling. Different strokes for different folks.
The particular benefits of sex in general are hotly debated (there are a number of plausible reasons, but we aren't sure which are the most important), and still the subject of a lot of interesting research. But the case for evolution doesn't rest upon knowing the answer to the purpose of every single element of nature. Evolutionary theory is a tool that can helps us find the answers, however.
Going with evoltionary process, are we to expect that in a few million years starfish will evolve eyes on the ends of their arms?
Understand that the very earliest multicellular life wouldn't have had "skin cells" or "brain cells" or anything like that. It wouldn't have had many specialized cells at all. It likely would have been something similar to the very simple flatworms we are familiar with today. This is a common theme throughout evolution: you can't think of some feature developing in isolation and then suddenly linking up with another well-developed system out of the blue. Instead, the development of all these things is likely to have been concurrent. Eyes likely developed in the way I linked to, and in terms of their relation to the nervous system, they developed along WITH the nervous system, which at hte time of eyespots had nothing like a brain, and perhaps not even really any nerves in the way we understand them.
And remember, the evolution of the mammalian eye we have is not the same story as the development of the cephlapod eye (which is superior to ours). The link between the two (when last we shared a common ancestor) is way back in time: back when "eyes" were just eyespots. How these different structures develop is thus quite different.
Your question about links to the brain actually seems to be about embryonic development, which is a little different than discussing evolution per se. In mammals, eyes do indeed develop as extensions of the brain. But this doesn't mean that in evolutionary history, brains came first and eyes developed later. It just means that the tissue types currently are controled by roughly the same areas of development in the embryo. How embryonic development meshes with evolutionary history is actually a very very complicated subject that would involve discussing how genes work, how they get expressed over the course of embryonic development, how modifications can be made to various sequences, and so forth.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->Going with evoltionary process, are we to expect that in a few million years starfish will evolve eyes on the ends of their arms?<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
There is no way to say. Starfish, of course, already have "eyecups" at the end of each arm, which are useful for determining light and light direction in a simple way, though not really useful for "seeing" as we understand it. If the life of starfish suddenly comes to depend more and more on being able to better resolve images, then its certainly possible that these structures will gain more function, perhaps even via the way that mammalian eyes did. But then again, at present, starfish really don't seem to have any need to "see" since their food and and defensive mechanisms work without needing to see (given that they move so slowly, it's not clear what help this would be anyway), and evolving in this direction would require pressures favoring a lot more than just more complex eyes, but gradual changes to their entire nervous systems in the direction of being able to make use of more information.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->And remember, the evolution of the mammalian eye we have is not the same story as the development of the cephlapod eye (which is superior to ours). The link between the two (when last we shared a common ancestor) is way back in time: back when "eyes" were just eyespots. How these different structures develop is thus quite different.<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
Ok, I just want to make sure I'm tracking this correctly. What you are saying is that octopus (and like creatures) developed eyes differently from us - in fact in a "superior" way (they don't have blind spots.)
Now, if I were an evolutionist, such a thing would make sence to me - I mean, obviously having the rods and cones around the wrong way doens't make sence, neither does having the retanal nerve cells in the way blocking light.
But I'm not an evolutionist - so I ask "why" is it designed the way it is... perhaps octopus eyes aren't superior to our own (rather designed better for their environment).
2 possible explinations -
1. The extra blood flow helps with more accute vision (overall vision is weaker, but focusing is stronger).
2. The extra layers that "block" our vision actually act more as a filtering device that help stop scattered light, and also block out harmful carcenogenic rays.
Well, among many other things. Their eyes are also much more versatile physically, can see polarized light, and so on. But then, you're right: to speak of them as "superior" is probably a mistake, because these things are basically subjective given what sorts of needs one might have. Both sorts of eyes have adapted pretty well to take advantage of particular existing traits and operate in particular environment. But of course there is a sort of chicken/egg issue here.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->Now, if I were an evolutionist, such a thing would make sence to me - I mean, obviously having the rods and cones around the wrong way doens't make sence, neither does having the retanal nerve cells in the way blocking light.<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
Again, evolution itself doesn't "make sense" of things, it simply works with what's there. If rods and cones are a certain way, and can function that way, evolution, unlike a designer, can't simply "decide" to flip them entirely around even if it might make sense to do so.
<!--QuoteBegin--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><b>QUOTE</b> </td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->But I'm not an evolutionist - so I ask "why" is it designed the way it is... perhaps octopus eyes aren't superior to our own (rather designed better for their environment).
2 possible explinations -
1. The extra blood flow helps with more accute vision (overall vision is weaker, but focusing is stronger).
2. The extra layers that "block" our vision actually act more as a filtering device that help stop scattered light, and also block out harmful carcenogenic rays.<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
These are common creationist claims, but they still don't speak to the heart of the matter, and they're confused anyway. Inverted rods and cones don't necessarily make focusing stronger, and in fact by blocking out scattered light they actually make our vision more cloudy than it needs to be, not less (not to mention the need of the nerves to be transparent makes them much slower and less accurate). Blood flow certainly doesn't seem to be a problem for all the other sorts of eyes in the animal kingdom, inverted or not, and there's no reason a solution couldn't be worked out that didn't require an inversion. And there are many more obvious solutions for anti-carcinogenic functionality that wouldn't require an inversion, again, also found in other eyes in the animal kingdom (besides which, do you actually have any evidence that the inversion really aids the prevention of cancer at all in the first place? And why should cancer of the receptor cells be better or worse than of the nerve cells?)
Furthermore, if cephlapod eyes are better adapted to their way of life, then why do fish living in the exact same environments have inverted eyes like us (they are more closely related to us, btw)? What's _their_ excuse?
The reality is that evolution can indeed make do and adapt basic structures pretty well in any environment, but it can't radically re-write major structures all at once unless there is some reason that explains the entire change. That's why even mammals that operate in same the sort of murky environments that cephlapods do can't just get cephlapod eyes. Evolution is stuck with working with what they have (and indeed, often develop solutions that don't involve eyes at all but are adapted from other senses, such as electrosense in the platypus).
The basic argument is less that human eyes have to be inferior than other eyes because of their structure (because all sort of other adaptations could compensate, and HAVE compensated in many cases) but that their particular strange structure is explained by their evolutionary history, not by any thinking design. There are all sorts of different solutions to all sorts of different problems of any particular design, leading to better or worse adaptations.
If you really wanted to disprove evolution using eyes, you should point to a cephlapod with inverted eyes or a mammal with non-inverted eyes.
1st: Thanks to Apos for this wonderful explanation thread.
2nd: The idea of Sexual Selection and other forms of Non-Natural Selection
3rd: The important concept of punctuated equilibrium with keeping in mind the rare occurance of fossilization.
1-------------------------
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2---------------------sexual selection
Natural Selection can occur when ANYTHING alters the reproductive rate of some creatures. Sexual selection is when some creatures are more attractive to the opposite sex and their offspring retain those attractive traits regardless of survivability.
The best example is the peacock, although this has occurred with many birds. The male peacock has a huge colorful tail that he uses to attract females. This huge tail has severe drawbacks, he cannot fly as well as a sparrow, he cannot hide as well as grouse or a duck, but his great grandfather still had more offspring and his species was born and has survived.
Among creatures intelligent enough to care about the looks of their sexual partner (not just superficialy, a tiger female wants her kittens to be with a strong and agile father) are susceptible to this counter-productive force. The current human body shapes were chosen this way as well. At the risk of getting offensive, let it be known that humans have the largest penises of all primates! You surely must agree that there is no benefit ecologically to such a tender organ being larger than physically required to get the job done.
3--------------------- Punctuated equilibrium.
This is the idea that evolution occured in spurts. as Apos mentioned the Guppy that grew much larger in a short timespan, when there is an evolutionary benefit to be easily had it will grow quickly. ('easily had' here means that it would be not a large change, body size is simple, but a new arm, no matter how useful, is not a simple change)
The idea serves to explain why we dont have fossil records of intermediate species. even though all land creatures came from water creatures, there are virtually no intermediates to be found. (amphibians are a whole separate family tree)
Evolution can happen pretty fast, on the order of several hundred generations, then the species will find a comfortable niche and have no reason to continue changing until some new pressing force comes into play. Presumably some predator forces the little mice to get faster and more camoflaged, but before the predator comes around the mice would stay slow and brightly colored for several millenia.
The end result is a million years of one kind of animal that was perfectly suited to his environment, then something changes, and this species shifts relatively rapidly to another formation.
FOSSILS are created rarely, some animal has to be buried under rock or silt before bacteria have a chance to decompose the bones completely, then the silt has to lie undisturbed until present time or else the fossils will be smashed and pulverized. Because this is rare with land creatures, we dont get to see a fossil for every generation there ever was. we only have random selections of the last few billion years, and this gives us a very hard time finding any of the quickly shifting intermediate species.
(fossils of bottom dwelling sea creatures are extremely common, most/all limestone is full of or made from pulverized seashells!)
Well, I'm not trying to disprove anything - just trying to ask pertinant questions. I would think that finding cephlapods with inverted eyes would point more strongly towards evolution and point to common ancestry being that as it stands we have a case of convergent adaptation - 2 diffent designs evolving independantly that serve the same purpose (3 if you count insect eyes). When playing the game of chance, I would think such occurences would not weigh in favor of evolution.
As to why octopus have one type of eye while fish have the other - in simiar environments with similar (cold blooded) anatomies - the one thing that came to mind was that octopus have less oxygen on average than fish - and because of the nature of thier eyes, they consume less oxygen as well.
Anyway, the link with some useful information:
<a href='http://www.creationevolution.net/inverted_retina1.htm' target='_blank'>linky, linky</a>
I don't know all the facts but racial memory is common in most animals including us. For instance if you were to paint a newborns room in a earthy green instead of pink or blue it will be much more relaxed and spend less time keeping you awake because when our anscestors were hiding in trees for survival it was associated with comfort and saftey. Dark blues are supposed to be very effective for people in positions of power to wear because it is associated with dominance.
This was all explained to me by a teacher who didn't have time to finish with the dark blue explanation but it makes sense to me.
this is inevitable, although the degree and rate may differ, perhaps conceivably even be negligible under certain circumstances. however the falling away from the specific points that advantaged the ancestors, the accumulating mutations, can be seen as <i>degradations</i>
certainly they are the source of new potential species, and in that sense they are not degradations. but by and large many mutations will not be particularly advantageous in that particular time and place, and these mutants will be poorly adapted and built in the relevant points as compared to their ancestors. yet so long as they are able to avoid population failure, these mutant strains will persist. the extreme changes are weeded out or else thrive and speciate in their appropriate, different environments, so here we still have a species that doesn't deviate too much, is more or less the same as the first of the ancestors of the species, but <b>worse</b>.
objectively the mutants might not be really "worse" but the development of the traits that proved advantageous to the ancestors of their species might compare unfavorably.
therefore so long as there is one species, the more time passes by, the more the species degrades in quality, in specific adaptation to their situation, until that is they maladapt so greatly that they are weeded out or become a new species.
although this is long winded (i am tired), some of you may see where this is going. human civilization has removed a lot of the selection pressures that shaped our direct species ancestors. consequently, harmful mutations are allowed to accumulate, so long as they do not significantly impair the survivability of the human offspring. the quality of the species is degrading, and there is no need to excel: humans can be mediocre and still get away with being human.
i only recently came across this view presented this way, although of course the realization that human civilization is affecting our evolution is obvious. but thinking it through, it seems that degradation of the human species is inevitable, until species failure
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hey, it's long and convoluted, i'm tired, but i know that my relevant audience will understand