illinialex24
Smash Hero
Hey guys, I have found that too many debates have revolved around evolution so I have decided to make 1 big thread discussing evolution.
What is Evolution?
It is essentially a change in characteristics from one generation to the other. This happens on two fundamental levels: in the genome and the epigenome. Essentially, evolution is a theory to explain how such a large amount of biodiversity came to be and why animals change over time. Please remember that in science, a theory is different than in basic speech.
Please note the plausible. A plausible theory after years of testing means that no or very little evidence contradicts it, and the contradicted parts are changed.
The "Discovery" of Evolution
Evolution was considered since ancient Greece, when it was theorized by a man named Anaximander. Later on, many other philosophers had a profound influence on the theory of evolution. One of them was Charles Darwin's grandfather. Another was Charles Lyell, who contradicted the then current belief that the geology of the world was explained by Noah's flood. However, he theorized that is was slow-moving forces that shaped the earth, and said the earth could be as old as 50 million years old. This had a profound influence on Charles Darwin, who came up with a method to explain evolution in 1838. While formulating it in 1858, he realized that a colleague of his was going to present a similar idea (Alfred Russel Wallace) and so they presented their idea at Linnean Society of London separately but at the same time.
Darwin's explanation for how evolution occurred, by natural selection, soon became a very accepted belief on how evolution occured.
Anaximander
Erasmus Darwin
Charles Lyell
Charles Darwin and Alfred Russel Wallace
What is Natural Selection?
Natural selection is an explanation for evolution. It states that each generation is not identical, and that members of the new generation differ slightly and these slight variations can either cause the organism in question to be more or less successful. A trait that makes it more successful will cause it to either live more often or have more children (sexual selection), so in the long run this trait will become widespread in the population. Unfavorable traits, on the other hand, will increase the chance of death or have a member of the population have less children, so eventually it will be weeded out of the population. However, traditional natural selection did not explain everything for how species evolved. A man named Mendel caused a major change in evolutionary theory.
Basic Natural Selection
Who was Mendel?
Mendel was monk who spent his time breeding pea plants. He noticed that while breeding two pure pea breeding families (like one with only white colored flowers or only purple flowers), that if they were breed together, that the next generation would have only purple flowers. However, if he breed these, exactly 1/4th of the the next generation would have white flowers, while 3/4 would have purple. He theorized that each characteristic is controlled by a gene and that there are different alleles for each gene. The alleles would either be dominant or recessive, and so in the pure breeding populations, the flowers would either have two dominant purple alleles or two recessive white alleles. However, when they mixed, each new flower would have one recessive and one dominant allele, meaning they would express the dominant allele. If he then breed those, 1/4 of the next population would have two recessive, 1/2 would have 1 recessive and 1 dominant, and 1/4 would have two dominant alleles (essentially a binomial distribution with p=1/2, if you don't know what this means, its a math term).
This was a crucial step because it showed that just because a trait isn't expressed doesn't mean it exists and so it was a major step in evolutionary theory later on. However, there were issues with Mendel's theories.
Mendel
What were the Issues with Mendel's Theory?
There were many issues with Mendel's theory, mainly because his theory was a much oversimplified version. First of all, not all genes had two alleles in the population. Some had many many alleles and others had few (blood type is an example of one that has more than 2, it has 3 alleles in the population). Also, not every gene dealt with 1 characteristic, some genes deal with many characteristics while sometimes many genes deal with 1 characteristic (like Sickle cell, a disease which can cause blood cells to become hard and destroy blood vessels and cause extreme pain. The gene, whether diseased or normal, causes a wide variety of effects. However, you have many genes that all deal with skin color. This is many genes for 1 trait).
Finally, there were issues with his view of dominant and recessive alleles. Some alleles, like those for flower color of snapdragons, can have incomplete dominance. This is because when the two alleles in the population mix (red and white), the result isn't a complete expression of either allele, instead it is a mix (the resulting flower color is pink). However, when these snapdragons breed, you get the traditional allele spread, with 1/4 of the resulting flowers red, 1/2 pink, and 1/4 white.
Also, sometimes, there is co-dominance, where both alleles are fully expressed. This happens in blood type. There is a fully recessive allele, type 0, and two co-dominant alleles, type A and B. If you have type O blood, it means you have two recessive O alleles. However, you can have A blood, B blood, or AB blood. This is because they are both co-dominant and so both traits are fully expressed. Mendel's basic work and the new discoveries in genetics caused a new version of evolution.
What was the new Version of Evolution?
It was modern synthesis, pretty much combining genetic theory and natural selection and keeping most of both theories. It stated that new variations are created when new alleles to genes are created by mutations to those genes and that these genes can either be favorable or detrimental to the survival of the organism. However, it made 1 key distinction not made in previous evolutionary theory. It is the survival of the gene, not the organism, that is crucial. For example, why bees are willing to kill themselves to protect invaders is because the other bees are genetically similar and so having it is better to save those genetically similar to yourself than yourself, as long as more are saved.
So why does this Affect Evolution?
This really changed evolution because it showed why many altruistic traits are spread throughout a population. It shows why you are willing to exert energy to save your brother and other genetically similar to yourself as opposed to strangers or other species. It shows why tadpoles waste lots of energy in creating and storing chemicals to warn other tadpoles of danger when they die, because saving solely themselves is less important than saving many others who would have died. It kept the fact that evolution was based off a population and not an individual (saying a population evolves, not the individual in question), however, that was recently changed because of a new discovery.
What Changed?
Recent science has shown that the individual can as well evolve. This is not based on what genes you have, but how they are expressed. For example, you may have a certain actively harming condition, but if the gene for it is "turned off", the gene won't be read so you should be fine. However, what we choose to do can change what genes are turned on and off.
This based off of how DNA is wrapped. DNA is wrapped in proteins called histones and made into a bundle called a chromosome so it can fit inside of a cell. However, if the DNA is wrapped too tightly around the proteins, it cannot be read. This is caused by acetylation and methylation. Acetlyation is a very temporary change where acetyl groups are added to the histones. This causes the gene to be read easier but it cannot be passed to the next generation. However, methylation, which causes the DNA to be wrapped tighter, it a very permanent change and reduces the expression of the gene. This can be passed along and allows an individual to actually change their characteristics with their choices.
So why all the Controversy?
Evolution is very controversial because of a few reasons. One of the major reasons is this quote in the Bible:
Also, there is another but small controversy against evolution because people are morally opposed to us being evolved from apes, believing we are morally and intelligently superior to apes and therefore better.
So what are the so-called "Proofs of Evolution"
There are 7 major proofs of evolution: The fossil record, comparative anatomy, comparative embryology, biogeography, biochemistry, artificial selection, and bacterial evolution.
Fossil Record
The fossil record is a very complete and accurate list of fossils showing the dates in which certain species lived and it shows animals slowly changing and eventually becoming something unrecognizable over time. In short, it shows evolution in action. It is much more accurate than those who argue against it and also has very accurate dating techniques. For dating, we use radiological dating whenever possible, which is a very accurate (its completely accurate, every study against it had a major fundamental flaw, IE, why carbon 14 levels don't go down in living animals is because they KEEP ingesting carbon 14) method to test how old something is. We compare the expected levels of some radioactive compounds to the actual levels and see how long it would have taken for it to decay that long. This then allows us to use certain species that are only seen in certain time periods and very common during those periods as marker fossils. These marker fossils are then used for dating other species where it is much more difficult to date them by radioactive decay.
Comparative Anatomy
If species were not evolving, we expect each and every species to have a unique way to move and fly and walk. They should have unique bone structures and the like, as well as unique results. However, we see two results: Homologous structures and analogous structures. Homologous structures are very similar structures (like the Whale, the bat, and the human forearm, all which have very similar anatomical similarities) being used for different reasons. This shows common descent and argues against the fact that all animals were spontaneously created and permanently fixed. It also shows that major evolutionary changes occur. Analogous structures are different structures being used differently. This shows that they are not related but evolved in a similar environment and it supports evolution because if both species were spontaneously created and had the same function, they should be very similar.
Comparative Embryology
Comparative embryology is a proof for evolution because as embryos develop, they develop in very different ways. For example, all animals that did not diverge from fish do not develop gills as an embryo. However, species that evolution predicts evolved from fish, like humans, have gills (called pharyngeal slits) some time during their development. This includes all mammals. Obviously, if we did not evolve from fish, this and the rest of our predicted closely related species would not develop this way.
Biogeography
Biogeography states that animals that are closer together but live in different environments are much more similar than those that live in similar environments but far apart. It supports evolution because if evolution didn't occur, those in the similar environments should be more similar, but if they had to evolve from each other, then those diverged from another species close to them should be more similar.
Biochemistry
It essentially supports the view of evolution because animals with a predicted closer relationship have more similar proteins or DNA, signifying that they likely evolved. This is because if each animal was independently created, each should have its own independent and unique proteins, instead, we see variations of each protein in many closely related species. The same is true for DNA.
Artificial Selection
Artificial selection is the ability of humans to change an animals characteristics by selecting for certain traits. This is seen in domestication, where we choose certain traits and create a species very different from the original. Kind of like how we took wild canines, domesticated them and created both Chihuahua's and Great Dane's. We have recorded history of these animals changing so if it can happen artificially, as long as a selecting mechanism occurs to an animal in the wild, it should occur in the wild.
Bacterial Evolution
This is the natural selection of bacteria as we speak to become resistant to antibiotics. We have recorded the evolution of bacteria from being almost completely susceptible to antibiotics to many strains being resistant to them. This is evolution as we speak and shows natural selection in action.
What About Intelligent Design?
Intelligent Design is an idea saying that God controlled evolution to create humans and all current animals and is based off the idea of irreducible complexity. Irreducible complexity says that some evolutionary gaps are so enormous and would have had to occur all at once so they have such a low probability of occurring that god must have influenced it. However, the argument is based on a very faulty belief in evolution. They believe evolution must cause an improvement in a certain object, and it must be the same function. For example, the use two main examples, one is a bacterial flagellum and another is a mouse trap. They argue that since the bacterial flagellum requires 8 parts and each of the 8 parts is crucial to its function, it could not have occurred spontaneously. However, who says it doesn't have a function missing 1 part. And we have found a very similar structure, almost identical missing 1 part that is used to inject toxins into cells by bacteria. This would have required only a small evolutionary change to become a flagellum.
The same is true for a mouse trap, take away the spring and you have a tie holder. Evolution doesn't direct itself, it works randomly so saying something is irreducibly complex is an invalid argument. Intelligent Design could be true, but since it plays no role in science. This is because if it does exist, we can predict how the higher power will control evolution and it will just appear random to us. Legislation has agreed that Intelligent Design is just a modern day version of creationism and is not to be taught in science classes.
So how does Evolution Occur?
Evolution is based on the creation of new genes through mutations. This is crucial to long term survival of a species because it allows the species to keep having new traits to help the species. However, there also other affects that really help a species. One of these is variation, new variations of genes can have an entirely new effect than before. This is why many species have sexual reproduction, so you can have the greatest variation, both at the chromosome level and the gene level (crossing over of genes on the chromosome, very common in humans, means that you don't just inherit chromosomes, which would have little variations, but a mix of genes on each chromosome).
There is also other forms of when a few members of the population either leave or survive a major extinction and their genes are different enough from the previous population to cause rapid evolution. This is called founder's effect or bottleneck effect. We see this commonly with the birds on the Galapagos Islands, a few birds would leave for a new island, become different enough to be their own species, and repeat, until we had many variations of birds.
Macro versus Micro Evolution
Some people argue that microevolution, the small differences between generations, exists, but macroevolution, the accumulation of these changes, does not. However, this is a very bad argument because we have both fossil evidence of this happening and common sense says that many small changes that are not all accumulated will eventually cause a large change in a species.
I hope you enjoyed that long explanation of the history, proofs, and mechanisms of evolution. I am not going to get into more complex stuff, like allopatric speciation and sympatric speciation. This is just a basic guide that should be useful for religious debates and ethical debates.
What is Evolution?
It is essentially a change in characteristics from one generation to the other. This happens on two fundamental levels: in the genome and the epigenome. Essentially, evolution is a theory to explain how such a large amount of biodiversity came to be and why animals change over time. Please remember that in science, a theory is different than in basic speech.
Wikpedia said:
Please note the plausible. A plausible theory after years of testing means that no or very little evidence contradicts it, and the contradicted parts are changed.
The "Discovery" of Evolution
Evolution was considered since ancient Greece, when it was theorized by a man named Anaximander. Later on, many other philosophers had a profound influence on the theory of evolution. One of them was Charles Darwin's grandfather. Another was Charles Lyell, who contradicted the then current belief that the geology of the world was explained by Noah's flood. However, he theorized that is was slow-moving forces that shaped the earth, and said the earth could be as old as 50 million years old. This had a profound influence on Charles Darwin, who came up with a method to explain evolution in 1838. While formulating it in 1858, he realized that a colleague of his was going to present a similar idea (Alfred Russel Wallace) and so they presented their idea at Linnean Society of London separately but at the same time.
Darwin's explanation for how evolution occurred, by natural selection, soon became a very accepted belief on how evolution occured.
Anaximander
Erasmus Darwin
Charles Lyell
Charles Darwin and Alfred Russel Wallace
What is Natural Selection?
Natural selection is an explanation for evolution. It states that each generation is not identical, and that members of the new generation differ slightly and these slight variations can either cause the organism in question to be more or less successful. A trait that makes it more successful will cause it to either live more often or have more children (sexual selection), so in the long run this trait will become widespread in the population. Unfavorable traits, on the other hand, will increase the chance of death or have a member of the population have less children, so eventually it will be weeded out of the population. However, traditional natural selection did not explain everything for how species evolved. A man named Mendel caused a major change in evolutionary theory.
Basic Natural Selection
Who was Mendel?
Mendel was monk who spent his time breeding pea plants. He noticed that while breeding two pure pea breeding families (like one with only white colored flowers or only purple flowers), that if they were breed together, that the next generation would have only purple flowers. However, if he breed these, exactly 1/4th of the the next generation would have white flowers, while 3/4 would have purple. He theorized that each characteristic is controlled by a gene and that there are different alleles for each gene. The alleles would either be dominant or recessive, and so in the pure breeding populations, the flowers would either have two dominant purple alleles or two recessive white alleles. However, when they mixed, each new flower would have one recessive and one dominant allele, meaning they would express the dominant allele. If he then breed those, 1/4 of the next population would have two recessive, 1/2 would have 1 recessive and 1 dominant, and 1/4 would have two dominant alleles (essentially a binomial distribution with p=1/2, if you don't know what this means, its a math term).
This was a crucial step because it showed that just because a trait isn't expressed doesn't mean it exists and so it was a major step in evolutionary theory later on. However, there were issues with Mendel's theories.
Mendel
What were the Issues with Mendel's Theory?
There were many issues with Mendel's theory, mainly because his theory was a much oversimplified version. First of all, not all genes had two alleles in the population. Some had many many alleles and others had few (blood type is an example of one that has more than 2, it has 3 alleles in the population). Also, not every gene dealt with 1 characteristic, some genes deal with many characteristics while sometimes many genes deal with 1 characteristic (like Sickle cell, a disease which can cause blood cells to become hard and destroy blood vessels and cause extreme pain. The gene, whether diseased or normal, causes a wide variety of effects. However, you have many genes that all deal with skin color. This is many genes for 1 trait).
Finally, there were issues with his view of dominant and recessive alleles. Some alleles, like those for flower color of snapdragons, can have incomplete dominance. This is because when the two alleles in the population mix (red and white), the result isn't a complete expression of either allele, instead it is a mix (the resulting flower color is pink). However, when these snapdragons breed, you get the traditional allele spread, with 1/4 of the resulting flowers red, 1/2 pink, and 1/4 white.
Also, sometimes, there is co-dominance, where both alleles are fully expressed. This happens in blood type. There is a fully recessive allele, type 0, and two co-dominant alleles, type A and B. If you have type O blood, it means you have two recessive O alleles. However, you can have A blood, B blood, or AB blood. This is because they are both co-dominant and so both traits are fully expressed. Mendel's basic work and the new discoveries in genetics caused a new version of evolution.
What was the new Version of Evolution?
It was modern synthesis, pretty much combining genetic theory and natural selection and keeping most of both theories. It stated that new variations are created when new alleles to genes are created by mutations to those genes and that these genes can either be favorable or detrimental to the survival of the organism. However, it made 1 key distinction not made in previous evolutionary theory. It is the survival of the gene, not the organism, that is crucial. For example, why bees are willing to kill themselves to protect invaders is because the other bees are genetically similar and so having it is better to save those genetically similar to yourself than yourself, as long as more are saved.
So why does this Affect Evolution?
This really changed evolution because it showed why many altruistic traits are spread throughout a population. It shows why you are willing to exert energy to save your brother and other genetically similar to yourself as opposed to strangers or other species. It shows why tadpoles waste lots of energy in creating and storing chemicals to warn other tadpoles of danger when they die, because saving solely themselves is less important than saving many others who would have died. It kept the fact that evolution was based off a population and not an individual (saying a population evolves, not the individual in question), however, that was recently changed because of a new discovery.
What Changed?
Recent science has shown that the individual can as well evolve. This is not based on what genes you have, but how they are expressed. For example, you may have a certain actively harming condition, but if the gene for it is "turned off", the gene won't be read so you should be fine. However, what we choose to do can change what genes are turned on and off.
This based off of how DNA is wrapped. DNA is wrapped in proteins called histones and made into a bundle called a chromosome so it can fit inside of a cell. However, if the DNA is wrapped too tightly around the proteins, it cannot be read. This is caused by acetylation and methylation. Acetlyation is a very temporary change where acetyl groups are added to the histones. This causes the gene to be read easier but it cannot be passed to the next generation. However, methylation, which causes the DNA to be wrapped tighter, it a very permanent change and reduces the expression of the gene. This can be passed along and allows an individual to actually change their characteristics with their choices.
So why all the Controversy?
Evolution is very controversial because of a few reasons. One of the major reasons is this quote in the Bible:
If you take Genesis literally, it states that God created animals according to their current kinds and he made man in his own image at the start of the earth. However, evolution contradicts this and says that animals were "created" (by that I mean they diverged evolutionary paths and evolved into creatures recognizable as some today) at much different times. And that humans evolved very late, definitely not within the first few days of the creation of the earth.Genesis said:
Also, there is another but small controversy against evolution because people are morally opposed to us being evolved from apes, believing we are morally and intelligently superior to apes and therefore better.
So what are the so-called "Proofs of Evolution"
There are 7 major proofs of evolution: The fossil record, comparative anatomy, comparative embryology, biogeography, biochemistry, artificial selection, and bacterial evolution.
Fossil Record
The fossil record is a very complete and accurate list of fossils showing the dates in which certain species lived and it shows animals slowly changing and eventually becoming something unrecognizable over time. In short, it shows evolution in action. It is much more accurate than those who argue against it and also has very accurate dating techniques. For dating, we use radiological dating whenever possible, which is a very accurate (its completely accurate, every study against it had a major fundamental flaw, IE, why carbon 14 levels don't go down in living animals is because they KEEP ingesting carbon 14) method to test how old something is. We compare the expected levels of some radioactive compounds to the actual levels and see how long it would have taken for it to decay that long. This then allows us to use certain species that are only seen in certain time periods and very common during those periods as marker fossils. These marker fossils are then used for dating other species where it is much more difficult to date them by radioactive decay.
Comparative Anatomy
If species were not evolving, we expect each and every species to have a unique way to move and fly and walk. They should have unique bone structures and the like, as well as unique results. However, we see two results: Homologous structures and analogous structures. Homologous structures are very similar structures (like the Whale, the bat, and the human forearm, all which have very similar anatomical similarities) being used for different reasons. This shows common descent and argues against the fact that all animals were spontaneously created and permanently fixed. It also shows that major evolutionary changes occur. Analogous structures are different structures being used differently. This shows that they are not related but evolved in a similar environment and it supports evolution because if both species were spontaneously created and had the same function, they should be very similar.
Comparative Embryology
Comparative embryology is a proof for evolution because as embryos develop, they develop in very different ways. For example, all animals that did not diverge from fish do not develop gills as an embryo. However, species that evolution predicts evolved from fish, like humans, have gills (called pharyngeal slits) some time during their development. This includes all mammals. Obviously, if we did not evolve from fish, this and the rest of our predicted closely related species would not develop this way.
Biogeography
Biogeography states that animals that are closer together but live in different environments are much more similar than those that live in similar environments but far apart. It supports evolution because if evolution didn't occur, those in the similar environments should be more similar, but if they had to evolve from each other, then those diverged from another species close to them should be more similar.
Biochemistry
It essentially supports the view of evolution because animals with a predicted closer relationship have more similar proteins or DNA, signifying that they likely evolved. This is because if each animal was independently created, each should have its own independent and unique proteins, instead, we see variations of each protein in many closely related species. The same is true for DNA.
Artificial Selection
Artificial selection is the ability of humans to change an animals characteristics by selecting for certain traits. This is seen in domestication, where we choose certain traits and create a species very different from the original. Kind of like how we took wild canines, domesticated them and created both Chihuahua's and Great Dane's. We have recorded history of these animals changing so if it can happen artificially, as long as a selecting mechanism occurs to an animal in the wild, it should occur in the wild.
Bacterial Evolution
This is the natural selection of bacteria as we speak to become resistant to antibiotics. We have recorded the evolution of bacteria from being almost completely susceptible to antibiotics to many strains being resistant to them. This is evolution as we speak and shows natural selection in action.
What About Intelligent Design?
Intelligent Design is an idea saying that God controlled evolution to create humans and all current animals and is based off the idea of irreducible complexity. Irreducible complexity says that some evolutionary gaps are so enormous and would have had to occur all at once so they have such a low probability of occurring that god must have influenced it. However, the argument is based on a very faulty belief in evolution. They believe evolution must cause an improvement in a certain object, and it must be the same function. For example, the use two main examples, one is a bacterial flagellum and another is a mouse trap. They argue that since the bacterial flagellum requires 8 parts and each of the 8 parts is crucial to its function, it could not have occurred spontaneously. However, who says it doesn't have a function missing 1 part. And we have found a very similar structure, almost identical missing 1 part that is used to inject toxins into cells by bacteria. This would have required only a small evolutionary change to become a flagellum.
The same is true for a mouse trap, take away the spring and you have a tie holder. Evolution doesn't direct itself, it works randomly so saying something is irreducibly complex is an invalid argument. Intelligent Design could be true, but since it plays no role in science. This is because if it does exist, we can predict how the higher power will control evolution and it will just appear random to us. Legislation has agreed that Intelligent Design is just a modern day version of creationism and is not to be taught in science classes.
So how does Evolution Occur?
Evolution is based on the creation of new genes through mutations. This is crucial to long term survival of a species because it allows the species to keep having new traits to help the species. However, there also other affects that really help a species. One of these is variation, new variations of genes can have an entirely new effect than before. This is why many species have sexual reproduction, so you can have the greatest variation, both at the chromosome level and the gene level (crossing over of genes on the chromosome, very common in humans, means that you don't just inherit chromosomes, which would have little variations, but a mix of genes on each chromosome).
There is also other forms of when a few members of the population either leave or survive a major extinction and their genes are different enough from the previous population to cause rapid evolution. This is called founder's effect or bottleneck effect. We see this commonly with the birds on the Galapagos Islands, a few birds would leave for a new island, become different enough to be their own species, and repeat, until we had many variations of birds.
Macro versus Micro Evolution
Some people argue that microevolution, the small differences between generations, exists, but macroevolution, the accumulation of these changes, does not. However, this is a very bad argument because we have both fossil evidence of this happening and common sense says that many small changes that are not all accumulated will eventually cause a large change in a species.
I hope you enjoyed that long explanation of the history, proofs, and mechanisms of evolution. I am not going to get into more complex stuff, like allopatric speciation and sympatric speciation. This is just a basic guide that should be useful for religious debates and ethical debates.
Actually, I don't believe in Evolution, but I still read it. It's good to be informed about both sides of the story. Very good topic indeed. 
im teasing. 