Evolution - Or rather Natural Selection - Explained
Selection
First of all you need to understand the effects of selection under any circumstances. Actually it's really easy to prove this even to the most trenchant of opponents of Evolution. First of all ask yourself these simple questions:
People started breeding animals for a variety of reasons. They quickly realized that if they kept a male animal that was big and strong and good at whatever behavior was desired and bred from him they'd get more of the type of animal they wanted in the next generation. They'd then further enhance this in the generation afterwards and so on.
These different cattle are pretty good evidence of how selection works in farming. All come from the same species.
Artificial Selection is the guiding principle of good animal husbandry. It's pretty much an established science with well understood methods.
This principle is also used in botany and agriculture to produce different strains of plant.
It's difficult to argue that if people select breeding individuals with a mind to promoting different characteristics you get massive variation within a species. The evidence is overwhelming.
Seeing as all these breeds started as the wolf it's pretty remarkable how far we've come in a few thousand years.
So how does selection take place in nature?
Selection takes place in nature via pressures in the environment. Say for example all the food in a particular environment is all difficult to catch because it runs away. The best individuals at chasing down that prey will feed first. In times of hardship they may be the only ones who survive to breed. The characteristics that made them good at catching food will be passed on in favour of those possessed by others in their species. If this hardship persists and there is a limited amount of food, each generation will become increasingly more adept at catching prey or it will simply not breed because its more successful cousins will edge it out. In short, its genes will become extinct. If all the members of a particular species cannot catch prey and starve to death they will all die: the species becomes extinct.
Should the species come through this sufficiently lengthy time of hardship, it will be markedly different to the time before. The particular individuals with the best adaptations to the challenges they faced have survived. They may be faster, cleverer, better at jumping or whatever it took to make it through.
If you then go to another population that had it easy in the same time period you are less likely to see this happen. All individuals will survive to breed based on pure chance events as they faced little environmental pressure and they are unlikely to have changed overmuch. This explains those special types of creatures, the living fossils! So unchanged has been their environment, and so well adapted to it are they that they remain unchanged for millions, sometimes hundreds of millions of years.
If the time period is sufficient the two populations may not even be able to interbreed, or produce sterile offspring should they attempt to hybridise, as in the case with donkeys and horses which produce sterile mules. They may be so markedly different that you can describe them as different species.
This is simply due to the shuffling of genes and can be achieved without any mention of mutations.
This is the basic principle of Natural Selection, or Survival of the Fittest. It uses precisely the same mechanisms as animal breeding by people, it's just harsh conditions in the environment that cause the selection to take place.
Timescales
One thing that people find hard to imagine is the timescales involved. For the vast majority of the history of life on Earth there was little more complex than bacteria and simple single cells. However, once animals with nervous systems and multicellular bodies came about things really took off. The ways these creatures could vary and adapt due to the much larger number of combinations of genes governing their structures was immense. Also, the sheer immensity of the timescales involved here allowed another factor other than gene shuffling to come into play.
Mutation
Mutations happen more often than you think but not so often as all that. Mutations are caused by something altering a gene. Most mutations have no or little significant effect, but sometimes the effects are dramatic.
Often the mutations are positively harmful and are quickly selected out - the unfortunate organism either being nonviable or being vulnerable to predation or suffering a disease, therefore dying before it can breed.
Occasionally these confer an advantage which gives rise to a whole host of possibilities for beneficial gene shuffling to rapidly create a new species. The simple fact these mutations worked and can be traced by gene analysis is evident in the successful dominance of the individuals now better equipped to survive in times of hardship. This is simple luck on behalf of the organisms benefitting from the mutation, but again, those best equipped to survive will always succeed to the detriment of those unfortunate organisms out-competed.
Over the sort of timescales we are discussing these once in a generation events soon gather pace and become very influential. A mutation that allows for better colour vision in a population relying on this trait to survive will very rapidly come to the fore. Over time, gene shuffling will further enhance this trait.
Organ development
The above diagram shows the evolution of the eye. Each is a snapshot in a sequence of miniscule incremental steps and not indicative of some instantaneous jump. At each stage of the process there would have to be an advantage for the individual further along the evolutionary trail over its predecessors. This is why a very large number of animals are blind or eyeless and plants have got along just fine without eyes at all. No advantage, why waste resources groing the organ? Organisms relying on such light sensitivity in a more accurate way would have a clear advantage over their less visually endowed forbears and so the eye develops. Examples for all stages of this eye development can be found throughout nature.
Other organs developed in similar ways.
So... Dodos Then
So why, sometimes, does evolution appear to go backwards?
Prime example, the dodo. Dodos had very little need to fly to escape predators, but it's highly likely their ancestors arrived by flying. All the necessary skeletal adaptations for flying were still there, but the flight muscles were atrophied. Why would an animal choose to give up such a massively useful thing as flying?
What's fairly obvious is that flying takes a huge amount of energy and developing and maintaining flight muscles is expensive in terms of food eaten to provide energy. Birds which didn't fly unnecessarily would begin to have an advantage in terms of saving energy in times of hardship. Birds with less developed flight muscles would be at an even bigger advantage as they weren't wasting energy and food resources even attempting to grow flight muscles in the first place. Over time, birds who couldn't be bothered to fly and who didn't even try to be good flyers genetically would come out on top over and above those birds genetically and behaviorally disposed to flying about. So gradually a species with no ground predators might as well not fly and become flightless and this is the mechanism by which it comes about. Many species of birds have taken this route in the past. Present species of note include ostriches, emus and kiwis.
Other examples of retrograde evolution where organs that have become redundant include naked mole rats (eyes and hair), humans (fur, the appendix, residual tail bones, gripping toes etc) and eyeless cave fish. In all cases relics of the redundant organs remain as the genetic instructions for their formation have not quite disappeared.
It's not about what is fancy and complex and impressive. It's about what is good for survival.
In Conclusion
Evolution is actually a very simple and easily demonstrated process. A hundred and more years of people applying Occam's razor and trying to shred it have had little impact other than to tweak and enhance it.
The various mechanisms involved are complex and take time. The principles behind it are not.
I have yet to find a single hole in it that does not vanish on investigation of painstakingly gathered evidence.
Hope this helps.
(These videos were created by a Theistic-Evolutionist. Someone who believes in god and evolution.)
Thank you for listing, and have a good day - MHO rocks.
Selection
First of all you need to understand the effects of selection under any circumstances. Actually it's really easy to prove this even to the most trenchant of opponents of Evolution. First of all ask yourself these simple questions:
- Have you ever seen different breeds of dogs?
- Do you accept that people choose dogs whose characteristics they want to pass on to the next generation to bring this about?
- Do you accept that way back before people started breeding dogs that all dogs looked pretty much the same and there were no Bulldogs, Dobermans, Labradors etc.?
People started breeding animals for a variety of reasons. They quickly realized that if they kept a male animal that was big and strong and good at whatever behavior was desired and bred from him they'd get more of the type of animal they wanted in the next generation. They'd then further enhance this in the generation afterwards and so on.
These different cattle are pretty good evidence of how selection works in farming. All come from the same species.
Artificial Selection is the guiding principle of good animal husbandry. It's pretty much an established science with well understood methods.
This principle is also used in botany and agriculture to produce different strains of plant.
It's difficult to argue that if people select breeding individuals with a mind to promoting different characteristics you get massive variation within a species. The evidence is overwhelming.
Seeing as all these breeds started as the wolf it's pretty remarkable how far we've come in a few thousand years.
So how does selection take place in nature?
Selection takes place in nature via pressures in the environment. Say for example all the food in a particular environment is all difficult to catch because it runs away. The best individuals at chasing down that prey will feed first. In times of hardship they may be the only ones who survive to breed. The characteristics that made them good at catching food will be passed on in favour of those possessed by others in their species. If this hardship persists and there is a limited amount of food, each generation will become increasingly more adept at catching prey or it will simply not breed because its more successful cousins will edge it out. In short, its genes will become extinct. If all the members of a particular species cannot catch prey and starve to death they will all die: the species becomes extinct.
Should the species come through this sufficiently lengthy time of hardship, it will be markedly different to the time before. The particular individuals with the best adaptations to the challenges they faced have survived. They may be faster, cleverer, better at jumping or whatever it took to make it through.
If you then go to another population that had it easy in the same time period you are less likely to see this happen. All individuals will survive to breed based on pure chance events as they faced little environmental pressure and they are unlikely to have changed overmuch. This explains those special types of creatures, the living fossils! So unchanged has been their environment, and so well adapted to it are they that they remain unchanged for millions, sometimes hundreds of millions of years.
If the time period is sufficient the two populations may not even be able to interbreed, or produce sterile offspring should they attempt to hybridise, as in the case with donkeys and horses which produce sterile mules. They may be so markedly different that you can describe them as different species.
This is simply due to the shuffling of genes and can be achieved without any mention of mutations.
This is the basic principle of Natural Selection, or Survival of the Fittest. It uses precisely the same mechanisms as animal breeding by people, it's just harsh conditions in the environment that cause the selection to take place.
Timescales
One thing that people find hard to imagine is the timescales involved. For the vast majority of the history of life on Earth there was little more complex than bacteria and simple single cells. However, once animals with nervous systems and multicellular bodies came about things really took off. The ways these creatures could vary and adapt due to the much larger number of combinations of genes governing their structures was immense. Also, the sheer immensity of the timescales involved here allowed another factor other than gene shuffling to come into play.
Mutation
Mutations happen more often than you think but not so often as all that. Mutations are caused by something altering a gene. Most mutations have no or little significant effect, but sometimes the effects are dramatic.
Often the mutations are positively harmful and are quickly selected out - the unfortunate organism either being nonviable or being vulnerable to predation or suffering a disease, therefore dying before it can breed.
Occasionally these confer an advantage which gives rise to a whole host of possibilities for beneficial gene shuffling to rapidly create a new species. The simple fact these mutations worked and can be traced by gene analysis is evident in the successful dominance of the individuals now better equipped to survive in times of hardship. This is simple luck on behalf of the organisms benefitting from the mutation, but again, those best equipped to survive will always succeed to the detriment of those unfortunate organisms out-competed.
Over the sort of timescales we are discussing these once in a generation events soon gather pace and become very influential. A mutation that allows for better colour vision in a population relying on this trait to survive will very rapidly come to the fore. Over time, gene shuffling will further enhance this trait.
Organ development
The above diagram shows the evolution of the eye. Each is a snapshot in a sequence of miniscule incremental steps and not indicative of some instantaneous jump. At each stage of the process there would have to be an advantage for the individual further along the evolutionary trail over its predecessors. This is why a very large number of animals are blind or eyeless and plants have got along just fine without eyes at all. No advantage, why waste resources groing the organ? Organisms relying on such light sensitivity in a more accurate way would have a clear advantage over their less visually endowed forbears and so the eye develops. Examples for all stages of this eye development can be found throughout nature.
Other organs developed in similar ways.
So... Dodos Then
So why, sometimes, does evolution appear to go backwards?
Prime example, the dodo. Dodos had very little need to fly to escape predators, but it's highly likely their ancestors arrived by flying. All the necessary skeletal adaptations for flying were still there, but the flight muscles were atrophied. Why would an animal choose to give up such a massively useful thing as flying?
What's fairly obvious is that flying takes a huge amount of energy and developing and maintaining flight muscles is expensive in terms of food eaten to provide energy. Birds which didn't fly unnecessarily would begin to have an advantage in terms of saving energy in times of hardship. Birds with less developed flight muscles would be at an even bigger advantage as they weren't wasting energy and food resources even attempting to grow flight muscles in the first place. Over time, birds who couldn't be bothered to fly and who didn't even try to be good flyers genetically would come out on top over and above those birds genetically and behaviorally disposed to flying about. So gradually a species with no ground predators might as well not fly and become flightless and this is the mechanism by which it comes about. Many species of birds have taken this route in the past. Present species of note include ostriches, emus and kiwis.
Other examples of retrograde evolution where organs that have become redundant include naked mole rats (eyes and hair), humans (fur, the appendix, residual tail bones, gripping toes etc) and eyeless cave fish. In all cases relics of the redundant organs remain as the genetic instructions for their formation have not quite disappeared.
It's not about what is fancy and complex and impressive. It's about what is good for survival.
In Conclusion
Evolution is actually a very simple and easily demonstrated process. A hundred and more years of people applying Occam's razor and trying to shred it have had little impact other than to tweak and enhance it.
The various mechanisms involved are complex and take time. The principles behind it are not.
I have yet to find a single hole in it that does not vanish on investigation of painstakingly gathered evidence.
Hope this helps.
(These videos were created by a Theistic-Evolutionist. Someone who believes in god and evolution.)
Thank you for listing, and have a good day - MHO rocks.
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