History UsefulNotes / Evolution

!!Evolution doesn't explain how life came about
* This is true but that isn't evolution's job. Evolution tells us how life changes once it's already here not how it formed in the first place. The latter is known as abiogenesis.

* This is true but that isn't evolution's job. Evolution tells us how life changes once it's already here not how it formed in the first place. The study of the latter is known as abiogenesis.

Evolution gives us organisms that can survive in their environments not organisms that are the best at surviving in their environments.

Evolution has two main components. The first is descent with modification. An offspring is ''like'' its parent(s) but not '''exactly''' like its parent(s). The reason for this is the random changes that occur in the propagation of genes between generations. Parent DNA is copied faithfully, but not exactly to the child. Sometimes part of the code gets pasted in backward, sometimes a chunk moves from page 1003 to page 1209, sometimes a bit is left out or another bit tacked on. There are a number of ways for information to be added, subtracted, or simply changed in a gene sequence.

Whereas an error in a computer program will cause it to crash and stop running, organisms can be more flexible. Sometimes a mutation can be crippling or fatal, other times it is a superficial change, and on some occasions the change is beneficial. The vast majority are completely neutral, either occurring in non-coding UsefulNotes/{{DNA}} or not changing the performance of the gene in which it occurs. You yourself are the heritor of some 120 (average number for humans) changes and aren't particularly crippled or enhanced by them. A specific mutation will typically only occur once and then spread through the population. Some mutations spread by virtue of being beneficial while others spread completely by chance in a process known as genetic drift. It is through genetic drift and mathematical models that scientists can trace evolutionary paths and genetic mutations back through history, in a process similar to the study of how language mutates over time.

Whereas an error in a computer program will cause it to crash and stop running, organisms can be more flexible. Sometimes a mutation can be crippling or fatal, other times it is a superficial change, and on some occasions the change is beneficial. The vast majority are completely neutral, either occurring in non-coding DNA or not changing the performance of the gene in which it occurs. You yourself are the heritor of some 120 (average number for humans) changes and aren't particularly crippled or enhanced by them. A specific mutation will typically only occur once and then spread through the population. Some mutations spread by virtue of being beneficial while others spread completely by chance in a process known as genetic drift. It is through genetic drift and mathematical models that scientists can trace evolutionary paths and genetic mutations back through history, in a process similar to the study of how language mutates over time.

Some myths have become attached to evolution and natural selection over the years:

* And no, humans are not specifically the target of evolution. Were you to rewind history a few million years and play it forward again, there is no guarantee that a species would emerge that was a) bipedal, b) intelligent or c) derived from the ape, all of which are significant commponents of ''Homo sapiens''. Were humanity to disappear today, it's questionable as to whether another species would achieve ''intelligence'', much less the other two.

* Evolution picks winners: In fact, evolution selects ''against'' organisms which are ill-suited to their environments rather than for organisms suited to them in that the genes which propagate themselves are the contestants. In a sense, "winning" evolution would be having children who have children who have children ad infinitum. There are no winners, just organisms that haven't lost ''yet''.
** Particularly tragic is the myth of Superior Species, particularly in the form of Social Darwinism: 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 lower back problems.
* Evolution is leading somewhere, or knows where it's going: evolution is a combination of random change and environmental pressure. What happens is that poorly adapted individuals die or reproduce less, not that something will magically appear that is perfectly suited to the environment. Happening as it does over hundreds of generations, modification and selection only guarantees you the minimum necessary to survive to this moment, not the best of all possible worlds. Take for example extremely isolated islands; in the absence of small mammals, birds adapted to fit the various niches that rodents would have occupied, but were then lethally out-competed when rodents showed up on European ships.
** Intelligence, and humans specifically, are the end goal: Were you to rewind history a few million years and play it forward again, there is no guarantee that a species of ape would have abandoned its brachiating ways for bipedal intelligence. Were humanity to disappear today, would another species achieve sapient intelligence? Perhaps. Raccoons, with their nifty little handpaws, and other hominids are good candidates, but intelligence is an expensive endeavor, and not one guaranteed to succeed.
* Evolution is just chance: One of the arguments thrown at evolution is that "none of this could have just happened by chance" (see above re: religion). No evolutionary biologist argues that this is the case. Chance is flipping a million coins and having them all land on heads. Evolution by descent with modification and natural selection is flipping a million coins, keeping the heads, flipping the rest, keeping the heads, flipping the rest...

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 grow higher than others to 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. 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.

** Intelligence, and humans specifically, are the end goal: Were you to rewind history a few million years and play it forward again, there is no guarantee that a species of ape would have abandoned its brachiating ways for bipedal intelligence. Were humanity to disappear today, would another species achieve sapient intelligence? Perhaps. Raccoons, with their nifty little handpaws, and our hominidae cousins are good candidates, but intelligence is an expensive endeavor, and not one guaranteed to succeed.

** Evolution doesn't necessarily mean change, either. Sharks are pretty much the same as they always were--and sharks evolved before dinosaurs; before flowers; before life on land; and even before fish with skeletons. Sharks are older than bones! And they haven't changed much, and are doing just fine.

Evolution has two main components. The first is a selection process--stated succinctly, that which survives to reproduce becomes more widespread. This is often referred to as ''natural'' selection, but in principle, we see selection processes every day. Whether you use Firefox or Chrome or Internet Explorer is a complex process of artificial selection, for example, and there are many reasons why different browsers control their respective market shares. Like organisms, companies, charities, even whole political systems spawn, grow, and die. What makes the evolution of organisms "natural" is that it has to do with conditions of adaptability, fertility, and more--what determines an organism's ability to propagate itself are factors derived from nature. And in the most trivial case, an organism that can't reproduce in some way (whether it's true sexual or asexual reproduction or simply the mechanism of a virus forcing a host cell to make copies) dies off and, well, vanishes.

The other major player in evolution is genetic drift, or the random errors that occur in the propagation of genes between generations. While in a program, a small error in code more likely than not causes it to stop running, in organisms, random mutations can be just as crippling or purely cosmetic or, more likely, somewhere in-between (most errors are actually completely neutral to the individual's chance of survival). Mutations contribute diversity in populations that, given enough pressure, can then be selected for or against by natural processes--it too is a key factor in further speciation and evolution of new organisms. Note: A specific mutation will only occur once and then spread through the population by being reproductively successful.

Notably, a number of conservative Christians have had issues reconciling evolutionary biology with TheBible's creation account in Genesis. Some have decided to take Genesis as metaphorical and/or believe that God drove the evolutionary process. Others say that the two views are irreconcilable and [[ScienceIsWrong side with the Biblical account]] (while they don't deny the selection process or genetic drift on a small scale, they believe it only goes as far as forming different breeds within a species, not entirely different species). The latter view is considered pseudoscience by the majority of people. Be careful when broaching the subject, though, as both sides tend to consider their views SeriousBusiness.

* 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.

Notably, a number of conservative Christians have had issues reconciling evolutionary biology with TheBible's creation account in Genesis. Some have decided to take Genesis as metaphorical and/or believe that God drove the evolutionary process. Others say that the two views are irreconcilable and [[ScienceIsWrong side with the Biblical account]] (while they don't deny the selection process or genetic drift on a small scale, they believe it only goes as far as forming different breeds within a species, not entirely different species). The latter view is considered pseudoscience by the majority of people. Be careful when broaching the subject, though, as both evolutionists and creationists tend to consider their views SeriousBusiness.

Notably, a number of conservative Christians have had issues reconciling evolutionary biology with TheBible's creation account in Genesis. Some have decided to take Genesis as metaphorical and/or believe that God drove the evolutionary process. Others say that the two views are irreconcilable and [[ScienceIsWrong side with the Biblical account]] (while they don't deny the selection process or genetic drift on a small scale, they believe it only goes as far as forming different breeds within a species, not entirely different species). The latter group is generally viewed by everyone else as not having OutgrownSuchSillySuperstitions. Be careful when broaching the subject, though, as both evolutionists and creationists tend to consider their views SeriousBusiness.

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 grow higher than others to 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 and outrun predators that might hunt them. 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.

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 grow higher than others to 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 and outrun predators that might hunt them. 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. Anything fit enough to survive will do so.

* Complex animals (read- the early ancestors of fish) have only been around for 550 million years or so
* 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.

Notably, a number of conservative Christians have had issues reconciling evolutionary biology with TheBible's creation account in Genesis. Some have decided to take Genesis as metaphorical and/or accept that God drove the evolutionary process. Others (while not denying the selection process or genetic drift on a small scale) say that the two views are irreconcilable and [[ScienceIsWrong side with the Biblical account]]; this group is generally viewed by everyone else as not having OutgrownSuchSillySuperstitions. Be careful when broaching the subject, though, as both evolutionists and creationists tend to consider their views SeriousBusiness.

Evolution has two main components. The first is a selection process--stated succinctly, that which survives to reproduce becomes more widespread. This is often referred to as ''natrual'' selection, but in principle, we see selection processes every day. Whether you use Firefox or Chrome or Internet Explorer is a complex process of artificial selection, for example, and there are many reasons why different browsers control their respective market shares. Like organisms, companies, charities, even whole political systems spawn, grow, and die. What makes the evolution of organisms "natural" is that it has to do with conditions of adaptability, fertility, and more--what determines an organism's ability to propagate itself are factors derived from nature. And in the most trivial case, an organism that can't reproduce in some way (whether it's true sexual or asexual reproduction or simply the mechanism of a virus forcing a host cell to make copies) dies off and, well, vanishes.

* While photosynthesis is absolutely ancient, flowering plants didn't appear til around 130 million years ago.

The other major player in evolution is genetic drift, or the random errors that occur in the propagation of genes between generations. While in a program, a small error in code more likely than not causes it to stop running, in organisms, random mutations can be just as crippling or purely cosmetic or, more likely, somewhere in-between (most errors are actually completely neutral to the individual's chance of survival). Mutations contribute diversity in populations that, given enough pressure, can then be selected for or against by natural processes--it too is a key factor in further speciation and evolution of new organisms. Note: A specific mutation will only occur once and then spread through the population by being reproductively successful.

The other major player in evolution is genetic drift, or the random errors that occur in the propagation of genes between generations. While in a program, a small error in code more likely than not causes it to stop running, in organisms, random mutations can be just as crippling or purely cosmetic or, more likely, somewhere in-between. Mutations contribute diversity in populations that, given enough pressure, can then be selected for or against by natural processes--it too is a key factor in further speciation and evolution of new organisms.

The world "evolution" in its most basic terms simply means "change over time". In biological terms, it is the inheritance of genetic traits within populations of organisms through successive generations. Evolution is one of the strongest-supported scientific theories, and is in fact the cornerstone of modern biology.

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