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* There are not "more evolved" (mammals and birds) and "less evolved" (reptiles, amphibians, fish, invertebrates, non-animal organisms) species. All living things are descended from a common ancestor, and have the same three or so billion years of evolution between then and now. (While species aren't more or less evolved, they can be more or less complex. Lineages can evolve from high to low complexity - think of the unicellular yeasts which evolve from multicellular fungal ancestors.) If you really pressed an evolutionary biologist to pick "more evolved" organisms, they'd reason that natural selection is most effective with short generation times and large populations, and therefore choose bacteria.
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* There are not "more evolved" (mammals and birds) and "less evolved" (reptiles, amphibians, fish, invertebrates, non-animal organisms) species. All living things are descended from a common ancestor, and have the same three or so billion years of evolution between then and now. (While species aren't more or less evolved, they can be more or less complex. Lineages can evolve from high to low complexity - think of the unicellular yeasts which evolve evolved from multicellular fungal ancestors.) If you really pressed an evolutionary biologist to pick "more evolved" organisms, they'd reason that natural selection is most effective with short generation times and large populations, and therefore choose bacteria.
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Changed line(s) 95,96 (click to see context) from:
* There are not "more evolved" (mammals and birds) and "less evolved" (reptiles, amphibians, fish, invertebrates, non-animal organisms) species. All living things are descended from a common ancestor, and have the same three or so billion years of evolution between then and now. (While species aren't more or less evolved, they can be more or less complex. Lineages can evolve from high to low complexity - think of lizards losing legs to become snakes.) If you really pressed an evolutionary biologist to pick "more evolved" organisms, they'd reason that natural selection is most effective with short generation times and large populations, and therefore choose bacteria.
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* There are not "more evolved" (mammals and birds) and "less evolved" (reptiles, amphibians, fish, invertebrates, non-animal organisms) species. All living things are descended from a common ancestor, and have the same three or so billion years of evolution between then and now. (While species aren't more or less evolved, they can be more or less complex. Lineages can evolve from high to low complexity - think of lizards losing legs to become snakes.the unicellular yeasts which evolve from multicellular fungal ancestors.) If you really pressed an evolutionary biologist to pick "more evolved" organisms, they'd reason that natural selection is most effective with short generation times and large populations, and therefore choose bacteria.
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* The first incorrect assumption is a somewhat pedantic one: modern humans did not evolve from modern monkeys. We do however descend from an ancestral monkey, which was the common ancestor of both humans and modern monkeys. The Old World monkeys (think macaques, baboons and langurs) are more closely related to apes than they are to the New World monkeys (think spider monkeys, howler monkeys, and capuchins). So any clade that includes both the Old and New World monkeys must also include the apes, and because the former two are monkeys, apes are monkeys as well. The same applies to the question "If people evolved from apes, ...", except that we're still apes, and by extension, monkeys. One of our two closest relatives is the [[http://en.wikipedia.org/wiki/Bonobo bonobo]], which [[SexTropes may explain a lot]]. The other one is the [[https://en.wikipedia.org/wiki/Chimpanzee chimpanzee]], which [[ViolenceTropes may also explain a lot]]
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* The first incorrect assumption is a somewhat pedantic one: modern humans did not evolve from modern monkeys. We do however descend from an ancestral monkey, which was the common ancestor of both humans and modern monkeys. The Old World monkeys (think macaques, baboons and langurs) are more closely related to apes than they are to the New World monkeys (think spider monkeys, howler monkeys, and capuchins). So any clade that includes both the Old and New World monkeys must also include the apes, and because the former two are monkeys, apes are monkeys as well. The same applies to the question "If people evolved from apes, ...", except that we're still apes, and by extension, monkeys. One of our two closest relatives is the [[http://en.wikipedia.org/wiki/Bonobo bonobo]], which [[SexTropes may explain a lot]]. The other one is the [[https://en.wikipedia.org/wiki/Chimpanzee chimpanzee]], which [[ViolenceTropes may also explain a lot]]lot]].
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* The first incorrect assumption is a somewhat pedantic one: modern humans did not evolve from modern monkeys, or at least from ancestors that would be fully classed as monkeys; in fact, both humans and monkeys evolved from some common antecedent that predated the emergence of the first monkeys. It would be more correct to ask "If people evolved from ''apes''...", except that we're still apes. One of our closest relative is the [[http://en.wikipedia.org/wiki/Bonobo bonobo]], which [[SexTropes may explain a lot]].
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* The first incorrect assumption is a somewhat pedantic one: modern humans did not evolve from modern monkeys, or at least monkeys. We do however descend from ancestors that would be fully classed as monkeys; in fact, an ancestral monkey, which was the common ancestor of both humans and monkeys evolved from some common antecedent that predated the emergence of the first modern monkeys. It would be The Old World monkeys (think macaques, baboons and langurs) are more correct closely related to ask apes than they are to the New World monkeys (think spider monkeys, howler monkeys, and capuchins). So any clade that includes both the Old and New World monkeys must also include the apes, and because the former two are monkeys, apes are monkeys as well. The same applies to the question "If people evolved from ''apes''...apes, ...", except that we're still apes. apes, and by extension, monkeys. One of our two closest relative relatives is the [[http://en.wikipedia.org/wiki/Bonobo bonobo]], which [[SexTropes may explain a lot]]. The other one is the [[https://en.wikipedia.org/wiki/Chimpanzee chimpanzee]], which [[ViolenceTropes may also explain a lot]]
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** Animals (everything from jellyfish to scorpions to elephants) might have only been around for 550 million years or so.
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** Animals (everything from jellyfish to scorpions to elephants) might have only been around for 550 650 million years or so.
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** "Modern" humans only really popped up around 200,000 years ago.
** Cro-Magnons (the first ''Homo sapiens'') originated around 50,000 years ago.
** Cro-Magnons (the first ''Homo sapiens'') originated around 50,000 years ago.
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** "Modern" Anatomically modern humans (''Homo sapiens sapiens'') only really popped up around 200,000 300,000 years ago.
**Cro-Magnons (the The first behaviorally modern ''Homo sapiens'') sapiens'' originated around 50,000 years ago.
ago, these humans were characterized by more advanced tools and artwork.
**
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In the same fashion, you have the clade Dinosauria, which includes birds and non-avian dinosaurs. Go back to an earlier ancestor and you have the Archosauria, which clade includes dinosaurs (including birds), pterosaurs and pseudosuchians (crocodiles and friends). Go back further and your clade becomes Diapsida, including Archosauria, Lepidosauria (lizards and snakes) and maybe Testudines (turtles, which were once though to be non-diapsid reptiles). At that point your clade includes all living reptiles and, under the Linnaean system, would have been considered Kingdom Animalia, Phylum Cordata, Class Reptilia. However, your clade ''also'' includes the birds, which under Linnaeus were sorted into the separate Class of Aves.
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In the same fashion, you have the clade Dinosauria, which includes birds and non-avian dinosaurs. Go back to an earlier ancestor and you have the Archosauria, which clade includes dinosaurs (including birds), pterosaurs and pseudosuchians (crocodiles and friends). Go back further and your clade becomes Diapsida, including Archosauria, Lepidosauria (lizards and snakes) and maybe Testudines (turtles, which were once though thought to be non-diapsid reptiles). reptiles, but more recent genetic evidence points that they are most closely related to the aforementioned Archosaurs, with which they form the larger clade Archelosauria). At that point your clade includes all living reptiles and, under the Linnaean system, would have been considered Kingdom Animalia, Phylum Cordata, Chordata, Class Reptilia. However, your clade ''also'' includes the birds, which under Linnaeus were sorted into the separate Class of Aves.
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* A related misconception is about common ancestry. Bears, dogs, and cats (all members of the order Carnivora) are related, and bears and dogs are more closely related to each other than either is to cats (bears and dogs are both members of the suborder caniformia, while cats are members of feliformia). Thus you go back a certain amount of time and you find the common ancestor to both the bear and the dog. It is ''not'' a beardog. Rather, it shares characteristics common to both (hair, carnivorous diet), some that are unique to either (the ancestor walked flat on its feet [plantigrade, like us] whereas the dog family walks on its toes [digitigrade]), and some that are found in neither. The ancestor looked more like a badger (it wasn't one) than like either bears or dogs, but had a wider, more bearlike head; a snout longer than a bear's and shorter than a dog's; and it was about the size of a raccoon. You would have to go back even further to find the common ancestor of dogs, cats, and bears, and you'll find that it's not a fusion of the three modern forms. Instead it is a less well-defined, creature, with broader characteristics and without the specific adaptations any of them have today. What it ''did'' have was traits suited to its time and place that had the potential to turn into what those creatures became.
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* A related misconception is about common ancestry. Bears, dogs, and cats (all members of the order Carnivora) are related, and bears and dogs are more closely related to each other than either is to cats (bears and dogs are both members of the suborder caniformia, while cats are members of feliformia). Thus you go back a certain amount of time and you find the common ancestor to both the bear and the dog. It is ''not'' a beardog. Rather, it shares characteristics common to both (hair, carnivorous diet), some that are unique to either (the ancestor walked flat on its feet [plantigrade, like us] whereas the dog family walks on its toes [digitigrade]), and some that are found in neither. The ancestor looked more like a badger (it wasn't one) one, but considering that badgers are more closely related to bears than dogs, it would have been an ancestor to them as well.) than like either bears or dogs, but had a wider, more bearlike head; a snout longer than a bear's and shorter than a dog's; and it was about the size of a raccoon. You would have to go back even further to find the common ancestor of dogs, cats, and bears, and you'll find that it's not a fusion of the three modern forms. Instead it is a less well-defined, creature, with broader characteristics and without the specific adaptations any of them have today. What it ''did'' have was traits suited to its time and place that had the potential to turn into what those creatures became.
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''Selection pressure'' is a concept for how aggressive the selection process is, which determines ''how fast'' evolution occurs. It doesn't matter what type of selection this is, whether it's artificial selection or natural selection.
Let's take modern agriculture. If every year after a harvest only the strongest, tallest, tastiest, highest yield plants have their seeds taken and used for next year's crop, certain characteristics would rapidly change. If we don't do any selecting and just let the plants compete among themselves, these same traits might very well still evolve, but it would be much slower, since we're moving from culling "everything but the best" to "a wheat plant 1% taller might have 0.2% more offspring". For a more natural instance of high selection pressure, you can have highly detrimental mutations that are a death sentence. The bigger the difference in passing the trait on, the greater the selection pressure. Many mutations are going to be slight changes.
Let's take modern agriculture. If every year after a harvest only the strongest, tallest, tastiest, highest yield plants have their seeds taken and used for next year's crop, certain characteristics would rapidly change. If we don't do any selecting and just let the plants compete among themselves, these same traits might very well still evolve, but it would be much slower, since we're moving from culling "everything but the best" to "a wheat plant 1% taller might have 0.2% more offspring". For a more natural instance of high selection pressure, you can have highly detrimental mutations that are a death sentence. The bigger the difference in passing the trait on, the greater the selection pressure. Many mutations are going to be slight changes.
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!!!Myth: Evolution cannot explain complex organs like the eye.
This particular example actually stopped being used in certain circles because it's been ''so thoroughly rebutted'', but it's worth some discussion anyway. One of the claims against this is that something like the eye cannot spontaneously pop into being because it's so complex. This is actually correct, in that it's so unlikely we might as well just say the chance of it is zero. However, the theory of evolution does not make such a claim, and it is a misrepresentation to say it does.
To get something complicated like an eye, we need two things. One of which is that it results in a survival advantage which increases the chance of the trait being passed on. Being able to detect predators, prey, and information about the environment from range is obviously pretty beneficial in many cases [[note]]If you consider it from the perspective of someone blind, being able to detect food, danger, and gain information at light speed from range without needing to interact directly with something would seem like some sort of super power[[/note]]. Secondly, there needs to be a series of steps by which a complicated organ can evolve, ''with each step being more useful''.
So, if this is the case, we should be able to find evidence of all sorts of eyes, from simple "light/dark" sensors, to eyes that can roughly tell where the light is coming from, and so on, all the way up to advanced eyes. And this is indeed what we find. The following article [[https://en.wikipedia.org/wiki/Evolution_of_the_eye has more details]].
If you want an obvious counter argument to the claim "what good is half an eye", consider someone with a vision defect like long sightedness. Even without corrective lenses, okay they might not be reading much fine print or engaging in any aerial dogfights any time soon, or driving cars through town safely, but very few people would argue that such vision is so useless one might as well be blind.
One other point to mention here is that evolution can repurpose things, known as exaptation. An organ or feature might originally have another function and gradually take on a new role; as above every single step needs to be a survival advantage. A tiny wing might indeed be useless for flight [[note]]It's also possible to envision different levels of flight, from gliding, to limited flight, to full on flight[[/note]], but if the original purpose is for temperature regulation then it could provide a survival advantage, giving a full wing a chance to evolve. The new function can completely supplant the old function and be the driving factor for further evolution, with the original purpose no longer a consideration; the main factor for wing evolution nowadays would be expected to be its flight characteristics, even if they did originally evolve for thermoregulation.
This particular example actually stopped being used in certain circles because it's been ''so thoroughly rebutted'', but it's worth some discussion anyway. One of the claims against this is that something like the eye cannot spontaneously pop into being because it's so complex. This is actually correct, in that it's so unlikely we might as well just say the chance of it is zero. However, the theory of evolution does not make such a claim, and it is a misrepresentation to say it does.
To get something complicated like an eye, we need two things. One of which is that it results in a survival advantage which increases the chance of the trait being passed on. Being able to detect predators, prey, and information about the environment from range is obviously pretty beneficial in many cases [[note]]If you consider it from the perspective of someone blind, being able to detect food, danger, and gain information at light speed from range without needing to interact directly with something would seem like some sort of super power[[/note]]. Secondly, there needs to be a series of steps by which a complicated organ can evolve, ''with each step being more useful''.
So, if this is the case, we should be able to find evidence of all sorts of eyes, from simple "light/dark" sensors, to eyes that can roughly tell where the light is coming from, and so on, all the way up to advanced eyes. And this is indeed what we find. The following article [[https://en.wikipedia.org/wiki/Evolution_of_the_eye has more details]].
If you want an obvious counter argument to the claim "what good is half an eye", consider someone with a vision defect like long sightedness. Even without corrective lenses, okay they might not be reading much fine print or engaging in any aerial dogfights any time soon, or driving cars through town safely, but very few people would argue that such vision is so useless one might as well be blind.
One other point to mention here is that evolution can repurpose things, known as exaptation. An organ or feature might originally have another function and gradually take on a new role; as above every single step needs to be a survival advantage. A tiny wing might indeed be useless for flight [[note]]It's also possible to envision different levels of flight, from gliding, to limited flight, to full on flight[[/note]], but if the original purpose is for temperature regulation then it could provide a survival advantage, giving a full wing a chance to evolve. The new function can completely supplant the old function and be the driving factor for further evolution, with the original purpose no longer a consideration; the main factor for wing evolution nowadays would be expected to be its flight characteristics, even if they did originally evolve for thermoregulation.
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* Evolution can also produce extremely clunky solutions, since it only works on the principle of "this is better than what we already have". An analogy here is like climbing a mountain with waters rising around you. There might be a higher mountain on the other side of the valley, but you are trapped on the lower mountain and can only go upwards where you're more likely to survive. As an example, the optic nerve in many vertebrates (which includes humans) creates a blind spot because of the way the eye evolved, a flaw the cephalopod eye does not suffer from due to it evolving independently. Evolution needs a pathway where ''every single step'' increases survival chance; you can't take the hit and have a few million years of slightly worse eyes while you fix the optic nerve situation because you get better eyes in the longer term. The only "reset button", is where there's no longer a selection pressure being applied, and so a trait can randomly change or be lost because at this point it either has no effect on survivability and so makes no difference either way, or has actually become a hindrance. For instance, fish that become trapped in a dark area might evolve to lose their eyes over time because eyes still cost energy to run even if you can't see, and fish with less expensive or no eyes will be less likely to starve. If descendents of this fish ended up migrating to an area with light again, they could potentially re-evolve eyes, and possibly without a blind spot.
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* Evolution can also produce extremely clunky solutions, since it only works on the principle of "this is better than what we already have". An analogy here is like climbing a mountain with waters rising around you. There might be a higher mountain on the other side of the valley, but you are trapped on the lower mountain and can only go upwards where you're more likely to survive. As an example, the optic nerve in many vertebrates (which includes humans) creates a blind spot because of the way the eye evolved, a flaw the cephalopod eye does not suffer from due to it evolving independently. Evolution needs a pathway where ''every single step'' increases survival chance; the chance of passing on those traits; you can't take the hit and have a few million years of slightly worse eyes while you fix the optic nerve situation because you get better eyes in the longer term. The only "reset button", is where there's no longer a selection pressure being applied, and so a trait can randomly change or be lost because at this point it either has no effect on survivability and so makes no difference either way, or has actually become a hindrance. For instance, fish that become trapped in a dark area might evolve to lose their eyes over time because eyes still cost energy to run even if you can't see, and fish with less expensive or no eyes will be less likely to starve. If descendents of this fish ended up migrating to an area with light again, they could potentially re-evolve eyes, and possibly without a blind spot.
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* As mentioned above, evolution can also "reverse" if an environment changes and what was useful is no longer useful or becomes a hindrance. If the climate in an area cools, thicker fur can be an advantage. If it warms up again this might be a disadvantage and thinner fur evolves again. Or maybe a predator gets good at grabbing into fur and shorter fur makes it easier to escape. Regardless, at no stage is it a "regression", it is a continued adaption relative to the current environment.
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* This said, the sentiment behind this point does have some ''slight'' validity to it. Modern technology and medicine can reduce or eliminate selection pressures that used to influence human evolution, and selection pressure does determine the ''rate'' of evolution. If technology rendered every human equally likely to survive and pass on traits, evolution would indeed stop, but this is extremely unlikely to ever be realised. An example of human evolution is the gradual loss of wisdom teeth, this process is likely to slow down (assuming we don't genetically engineer our children to eliminate wisdom teeth), because the genes for "no wisdom teeth" have less of an influence on survivability when modern dentistry allows them to be removed with minimal complications, vs. starving to death on the African savannah because an impacted wisdom tooth caused a massive infection and losing half your teeth.
** Adding to this point, modern medicine might actually open up options to ''increase'' the rate of evolution in other areas. A baby's skull size and brain development is a trade off between allowing the mother to give birth while still being able to walk, and the risks of killing her in childbirth, and this likely posed an upper limit. Theoretically, modern medicine and procedures like a Caesarean section could remove a blocker on say evolving larger brains.
** Adding to this point, modern medicine might actually open up options to ''increase'' the rate of evolution in other areas. A baby's skull size and brain development is a trade off between allowing the mother to give birth while still being able to walk, and the risks of killing her in childbirth, and this likely posed an upper limit. Theoretically, modern medicine and procedures like a Caesarean section could remove a blocker on say evolving larger brains.
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* Evolution can also produce extremely clunky solutions, since it only works on the principle of "this is better than what we already have". An analogy here is like climbing a mountain with waters rising around you. There might be a higher mountain on the other side of the valley, but you are trapped on the lower mountain and can only go upwards where you're more likely to survive. As an example, the optic nerve in many vertebrates (which includes humans) creates a blind spot because of the way the eye evolved, a flaw the cephalopod eye does not suffer from due to it evolving independently. Evolution needs a pathway where ''every single step'' increases survival chance; you can't take the hit and have a few million years of slightly worse eyes while you fix the optic nerve situation because you get better eyes in the longer term. The only "reset button", is where there's no longer a selection pressure being applied, and so a trait can randomly change or be lost because at this point it either has no effect on survivability and so makes no difference either way, or has actually become a hindrance. For instance, fish that become trapped in a dark area might evolve to lose their eyes over time because eyes still cost energy to run even if you can't see, and fish with less expensive or no eyes will be less likely to starve. If descendents of this fish ended up migrating to an area with light again, they could potentially re-evolve eyes, and possibly without a blind spot.
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* The Earth itself is ~4.6 billion years old
* The first simple life (that is, prokaryotic and single cellular) appeared around 3.5 billion years ago. Multicellular life did not appear until around 1 billion years ago.
* Animals (everything from jellyfish to scorpions to elephants) have only been around for 550 million years or so (probably).
* Our genus, ''Homo'', is only about 2.5 million years old. That includes our earlier bipedal ancestors. "Modern" humans only really popped up around 200,000 years ago, and Cro-Magnons (the first ''Homo sapiens'') 50,000 years ago.
* While photosynthesis is absolutely ancient, flowering plants didn't appear until around 130 million years ago.
* The first simple life (that is, prokaryotic and single cellular) appeared around 3.5 billion years ago. Multicellular life did not appear until around 1 billion years ago.
* Animals (everything from jellyfish to scorpions to elephants) have only been around for 550 million years or so (probably).
* Our genus, ''Homo'', is only about 2.5 million years old. That includes our earlier bipedal ancestors. "Modern" humans only really popped up around 200,000 years ago, and Cro-Magnons (the first ''Homo sapiens'') 50,000 years ago.
* While photosynthesis is absolutely ancient, flowering plants didn't appear until around 130 million years ago.
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* The Earth itself is ~4.around 4.6 billion years old
old.
* The first simple life (that is, prokaryotic and single cellular) appeared around 3.5 billion yearsago. ago.
* Photosynthetic bacteria have been dated at 3.4 billion years old.
* Multicellular life did not appear until around 1 billion years ago.
* ** Animals (everything from jellyfish to scorpions to elephants) might have only been around for 550 million years or so (probably).
so.
** Flowering plants didn't appear until around 130 million years ago.
* Our genus, ''Homo'', is only about 2.5 million years old. That includes our earlier bipedalancestors. ancestors.
** "Modern" humans only really popped up around 200,000 yearsago, and ago.
** Cro-Magnons (the first ''Homo sapiens'') originated around 50,000 years ago.
* While photosynthesis is absolutely ancient, flowering plants didn't appear until around 130 million years ago.
* The first simple life (that is, prokaryotic and single cellular) appeared around 3.5 billion years
* Photosynthetic bacteria have been dated at 3.4 billion years old.
* Multicellular life did not appear until around 1 billion years ago.
** Flowering plants didn't appear until around 130 million years ago.
* Our genus, ''Homo'', is only about 2.5 million years old. That includes our earlier bipedal
** "Modern" humans only really popped up around 200,000 years
** Cro-Magnons (the first ''Homo sapiens'') originated around 50,000 years ago.
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** Evolution is a descriptive theory about how species operate and not a prescriptive theory about human ethics.
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** Evolution is a descriptive theory about how species operate and not a prescriptive theory about human ethics. ethics - that is, it's about how nature '''is''', not how society '''should''' be.
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-->-- '''PZ Meyers'''
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-->-- '''PZ Meyers'''
Myers'''
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Major factors that drive speciation through selection are geographical or climatological in nature: when populations get separated by mountains or rivers, the split-off groups can diverge; when the local weather patterns turn more rainy or warmer, creatures built for cold, dry weather die off. Additionally, a creature may have a competitive advantage for limited resources. Plants that grow higher than others get a clear, unobstructed path to sunlight. Animals that are faster, bigger, or tougher can more easily kill their prey, or those that are fast and quick can outrun predators that might hunt them, or those that are smaller and weaker require less food and so do not starve. Organisms that are more attractive to the opposite sex can have more offspring. There are too many factors to list, of course; this is just a sample of what all affects an organism's ability to reproduce, to survive selection and the passage of time. In the end, no matter the cause, that which survives to reproduce becomes more prevalent, whatever that may be. It's a misconception to think only the "fittest" survive; this is not true. There's an element of chance (anyone can get hit by a falling rock). Plus, a great number of organisms survive to have children; it's whether they have ''more'' surviving children and grandchildren that determines the course of change.
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Major factors that drive speciation through selection are geographical or climatological in nature: when populations get separated by mountains or rivers, the split-off groups can diverge; when the local weather patterns turn more rainy rainier or warmer, creatures built for cold, dry weather die off. Additionally, a creature may have a competitive advantage for limited resources. Plants that grow higher than others get a clear, unobstructed path to sunlight. Animals that are faster, bigger, or tougher can more easily kill their prey, or those that are fast and quick can outrun predators that might hunt them, or those that are smaller and weaker require less food and so do not starve. Organisms that are more attractive to the opposite sex can have more offspring. There are too many factors to list, of course; this is just a sample of what all affects an organism's ability to reproduce, to survive selection and the passage of time. In the end, no matter the cause, that which survives to reproduce becomes more prevalent, whatever that may be. It's a misconception to think only the "fittest" survive; this is not true. There's an element of chance (anyone can get hit by a falling rock). Plus, a great number of organisms survive to have children; it's whether they have ''more'' surviving children and grandchildren that determines the course of change.
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An alternative terminology is "monophyletic" and "paraphyletic". A monophyletic group is (by definition) a clade. A group of organisms which is not monophyletic is paraphyletic. For example, "fish" is a paraphyletic group, because there exist organisms (e.g. all land vertebrates) which are descended from fish but are not fish. However "cat" is monophyletic (a clade) - all current cat species are descended from a single ancestral proto-cat, and all descendents of the proto-cat are in the group "cat". The classification of some groups is surprising - brown (grizzly) bears are paraphyletic (any clade including all brown bears also includes polar bears.)
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An alternative terminology is "monophyletic" "monophyletic", "paraphyletic", and "paraphyletic".polyphyletic. A monophyletic group is (by definition) a clade. A group of organisms which excludes one group descended from that group is not monophyletic is paraphyletic.paraphyletic. A polyphyletic group consists of unrelated organisms that just so happens to resemble each other. For example, "fish" is a paraphyletic group, because there exist organisms (e.g. all land vertebrates) which are descended from fish but are not fish. However "cat" is monophyletic (a clade) - all current cat species are descended from a single ancestral proto-cat, and all descendents descendants of the proto-cat are in the group "cat"."cat". The obsolete order "Insectivora" is polyphyletic, since golden moles and tenrecs are not closely related to shrews, moles, and hedgehogs, but were included in that group for a while before being moved to their own clade. The classification of some groups is surprising - brown (grizzly) bears are paraphyletic (any clade including all brown bears also includes polar bears.)
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This very same article later acknowledges 'some traits are just bad' when referencing a tendency to contract breast cancer. The only way this can be substantiated is by insisting scientific concepts can never have moral implications. Which means denying the existence of morality in general.
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* Particularly tragic is the myth of Superior Species, particularly in the form of SocialDarwinism. No creature is inherently "better" than another. A cheetah is particularly well adapted to running down fast prey, but it will never outfight a bear, which will never be as deft with its paws as a raccoon, who can't swim with the fishes, who don't know how to do math. We are each of us what we are, with nearly the same 3.5 billion years of evolutionary history behind us. And a tree won't have nukes, anger and lower back problems.
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