- #1
DaveC426913
Gold Member
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I have read some amount of literature on evolution and natural selection over the years and, while I certainly learn a lot, it never seems to quite help me grok the breadth of change over deep time.
So I have some rather naive thoughts that I'll phrase in the form of incredulity. They are simplified, for the sake of brevity; I understand that it's a nuanced topic.
I don't for a second doubt that it's the case, I just have to ... trust in the science.
1] Dogs are bred for different things. (Not the best starter topic, since this involves artificial selection) Terriers are bred for digging. If we assume that this is an instinctive trait (not learned from a parent), then there is something in the wiring of the brain that tells all these dogs to dig. Their DNA, the only thing a breed has in-common with its kin, must encode the genes to build the neural pathways that cause it to want to dig. That, and ten thousand other subtle behaviors must be encoded in the genes, which cause proteins to make pathways, which survive the embryonic process to birth, which cause it to ... what? dig? That subtlety of encoding is virtually inconceivable to me.
2] Complex mammals dream; cats do; dogs do. I suppose rodents do too. I'm not sure about non-mammals. That means that the process for dreaming must have come from their common ancestor - that shrew that lived alongside the Tyrannosaur 80 million years ago. If more distant animals - such as any of the mammals' classificationary cousins - also dream, that means dreaming was well-established even before mammals split off. Unless we are going for convergent evolution here...
3] Cows have tufted tails, the better to swat flies away with, and over-large eyelashes that help keep flies out of their eyes (pick any other subtle traits). They evolved these things as an evolutionary advantage (granted, this is oversimplified). Does this mean that of the one gajillion cowoids that went before it, a statistically significant number of them died or were unable to breed effectively because they had short eyelashes and broom-like tails? I should find a better example but, in essence, does it not hold true that a critter has some subtle trait because .9999 gajillion of its ancestors dies whereas of those that di not have that trait a whole gajillion died? I am aware that many traits evolved alongside other traits, without any apparent advantage. Still, the net outcome is that advantageous traits - even ridiculously subtle ones - were selected for.
4] I imagine an idealized critter, with only two traits, say, a blob that has a skin-texture and a leg-length.
The smooth-skinned has a slight advantage over pebbly-skin, but long legs has an advantage over short legs. (Let's say they live on the surface of fast-running water or some such). Smooth skin prevails over pebbly-skin, but in doing-so, wipes out a bunch of long-legged, pebbly-skinned varieties. Ultimately, the two traits evolve independent of each other. Skin gets smoother, legs get longer, even though many of both kinds of being wiped out.
I guess I can see it at the scale of just a few traits, but the number of individual traits of any complex critter is virtually uncountable. This critter has wider tubes for its lymph nodes, that critter has striations in its liver, another critter has eyes nearer the top of its head, yet another has smaller blood corpuscles. It is virtually unfathomable that these traits can evolve essentially independent of each other in a population, when the traits are essentially competing with each other to "help" the critters survive.
Some day I want to write a program like this. An idealized critter, with a hundred traits, all with some sort of (unknown!) advantage or disadvantage, or both - (traits that, in the real world, might to allow it to - or prevent it from - breeding just one more time than its neighbor). I want to run it against an idealized "challenging landscape". The challenges are just idealized properties as well; just randomly-invoked events - one knocks these traits up and those ones down, another knocks this set up and that set down. Of course, the sets of traits affected will strongly overlap - in a sense the traits themselves are competing. I want to watch and see if, after 10,000 generations, the critters remaining will have selected traits that equate to advantages. Someday...
So I have some rather naive thoughts that I'll phrase in the form of incredulity. They are simplified, for the sake of brevity; I understand that it's a nuanced topic.
I don't for a second doubt that it's the case, I just have to ... trust in the science.
1] Dogs are bred for different things. (Not the best starter topic, since this involves artificial selection) Terriers are bred for digging. If we assume that this is an instinctive trait (not learned from a parent), then there is something in the wiring of the brain that tells all these dogs to dig. Their DNA, the only thing a breed has in-common with its kin, must encode the genes to build the neural pathways that cause it to want to dig. That, and ten thousand other subtle behaviors must be encoded in the genes, which cause proteins to make pathways, which survive the embryonic process to birth, which cause it to ... what? dig? That subtlety of encoding is virtually inconceivable to me.
2] Complex mammals dream; cats do; dogs do. I suppose rodents do too. I'm not sure about non-mammals. That means that the process for dreaming must have come from their common ancestor - that shrew that lived alongside the Tyrannosaur 80 million years ago. If more distant animals - such as any of the mammals' classificationary cousins - also dream, that means dreaming was well-established even before mammals split off. Unless we are going for convergent evolution here...
3] Cows have tufted tails, the better to swat flies away with, and over-large eyelashes that help keep flies out of their eyes (pick any other subtle traits). They evolved these things as an evolutionary advantage (granted, this is oversimplified). Does this mean that of the one gajillion cowoids that went before it, a statistically significant number of them died or were unable to breed effectively because they had short eyelashes and broom-like tails? I should find a better example but, in essence, does it not hold true that a critter has some subtle trait because .9999 gajillion of its ancestors dies whereas of those that di not have that trait a whole gajillion died? I am aware that many traits evolved alongside other traits, without any apparent advantage. Still, the net outcome is that advantageous traits - even ridiculously subtle ones - were selected for.
4] I imagine an idealized critter, with only two traits, say, a blob that has a skin-texture and a leg-length.
The smooth-skinned has a slight advantage over pebbly-skin, but long legs has an advantage over short legs. (Let's say they live on the surface of fast-running water or some such). Smooth skin prevails over pebbly-skin, but in doing-so, wipes out a bunch of long-legged, pebbly-skinned varieties. Ultimately, the two traits evolve independent of each other. Skin gets smoother, legs get longer, even though many of both kinds of being wiped out.
I guess I can see it at the scale of just a few traits, but the number of individual traits of any complex critter is virtually uncountable. This critter has wider tubes for its lymph nodes, that critter has striations in its liver, another critter has eyes nearer the top of its head, yet another has smaller blood corpuscles. It is virtually unfathomable that these traits can evolve essentially independent of each other in a population, when the traits are essentially competing with each other to "help" the critters survive.
Some day I want to write a program like this. An idealized critter, with a hundred traits, all with some sort of (unknown!) advantage or disadvantage, or both - (traits that, in the real world, might to allow it to - or prevent it from - breeding just one more time than its neighbor). I want to run it against an idealized "challenging landscape". The challenges are just idealized properties as well; just randomly-invoked events - one knocks these traits up and those ones down, another knocks this set up and that set down. Of course, the sets of traits affected will strongly overlap - in a sense the traits themselves are competing. I want to watch and see if, after 10,000 generations, the critters remaining will have selected traits that equate to advantages. Someday...