Defining evolution
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03-03-2013, 03:08 AM
RE: Defining evolution
(02-03-2013 09:46 AM)Ghost Wrote:  Evolution is a process in which adaptive inherited replicator mutations are selected for and maladaptive inherited replicator mutations are selected against at the level of the phenotype within the context of a given population's replicator pool in a given environment. The constant selection of mutations causes an array of changes within that population over time (see "punctuated equilibrium"); changes that influence the evolution of other populations within that given environmental context, as well as other replicator types, and vice versa. When populations become separated by space-time, the accumulation of these changes can lead to a divergence between the separated groups, called drift, that, along with punctuated equilibrium, can result in cladogenesis. Maladaptive mutations either lead to reductions in their representation in the replicator pool, or to outright extinctions; meaning that maladaptions are self-eliminating.

In the bolded part are you referring the genetic drift? My understanding of genetic drift is that it can happen in an unseperated population. For instance, although not likely, it is still logically possible that after the next 100(or some other number) generations of humans, everyone born who is a member of that 100th generation will be a ginger. They will be a ginger not because being ginger is more fit, but rather because of happenstance.

I think I can use your definition. I would prefer it dumbed down a bit so that people without more than a rudimentary education in evolution would understand it(thats one reason why I like my definiton). If you want to give a shot at dumbing it down a bit, I would appreciate it. If you don't I will go with it as is. I think a lot of atheists on this forum would reject my definition simply because I, a theist, wrote it and therefore it must be wrong. I think they would be more accepting of your defintion.
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03-03-2013, 08:57 AM
RE: Defining evolution
I'll give a very, very general definition?
Biological evolution refers to the change in allele frequency in a population over a period of time.

I prefer Phaedrus' definition. It's clear and easy to understand. Ghost's definition is very clear and specific, which I like as well, but might be daunting for some.

Also, another source of variation other than mutations: Processes in meiosis I such as crossing over (prophase I) and independent assortment (metaphase I).

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03-03-2013, 09:19 AM (This post was last modified: 03-03-2013 09:22 AM by Ghost.)
RE: Defining evolution
Hey, Wood.

I used the term drift (rather than the more narrow genetic drift) because you were interested in a broader definition of evolution.

In genetics, yes, absolutely, it would refer to genetic drift. In memetics, it would refer to memetic drift. For example, early American whites became separated from England and drift accounts for many changes in their culture; most predominantly their accent (although it goes much deeper than that).

One could call it replicator drift as well.

Quote: My understanding of genetic drift is that it can happen in an unseperated population. For instance, although not likely, it is still logically possible that after the next 100(or some other number) generations of humans, everyone born who is a member of that 100th generation will be a ginger. They will be a ginger not because being ginger is more fit, but rather because of happenstance.

Everyone? That's a near perfect statistical impossibility; statistically similar to each one of those children being born with a winning lottery ticket as well. That's the most important note.

That's not genetic drift. That's allele frequency.

The allele for red hair is recessive. That means that in order for it to be expressed, the child must get that gene from both of his parents (double recessive).

For the purpose of modelling, imagine that a dominant gene is represented by a capital letter (A) and a recessive gene by a lower case letter (a). There are three possible situations in simple dominance:
-AA: Two dominant genes in homozygous allele pairs. The dominant gene will be expressed.
-Aa: A dominant and a recessive gene in a heterozygous allele pair. The dominant gene will be expressed.
-aa: Two recessive genes in a homozygous allele pair. The recessive gene will be expressed.

Because recessive genes are only expressed when they are double recessive, the recessive allele can persist for generations before it finally hooks up with another recessive allele. So that "happenstance" you refer to is not happenstance. It's perfectly explainable by genetic theory.

What we're actually talking about here is allele frequency.

Every population has a gene pool. The gene pool is the sum total of all genes in that population. Let's stick with hair for now (to be clear, only ONE of the many genes in that gene pool). So say the gene pool for the Bea people contains alleles for black hair, brown hair, blonde hair and red hair. We now have to determine the allele frequency of that gene pool. Lets say 50% of the alleles for hair are black, 25% brown, 20% blonde and 5% red. This percentage value is referred to as REPRESENTATION. What is an allele's representation in the gene pool? Representation tells us a lot about what we can expect in terms of those traits popping up in that population. Dominance tells us even more.

Representation applies to all pools and for all replicator types. For example, we can look at Canada and ask, what is the representation of the English meme complex?

Anyhoo, as long as the ginger allele has a representation in the gene pool, it can pop up again provided it connects with another ginger allele.

The other possibility is that the ginger allele is a mutation that occurs in a population's gene pool and then increases in representation. That might seem like happenstance, but again, it's explained nicely by genetic theory.

Now let's say that the Bea people were separated from the Eh people when their island split in two. Say that the allele for black hair was a random mutation that occurred in the Bea people after that split. It's a dominant allele so it was very easy for it to spread within that gene pool. That's an example of drift.

Now imagine that a land bridge appears between the two islands. The gene pools of the Bea and Eh people are no longer separated by space-time. They can now fuck each other to their heart's content. And now that there is a space-time connection between their gene pools, genes can flow back and forth. This is called gene flow.

Flow applies to all pools and for all replicator types. For example, we can look at the cultural phenomenon of posting viral videos. Let's say that it originated in the US. For a very long time, the US was separated from Europe by space-time (The Atlantic ocean). The only way across was by boat (not perfect separation, but enough that the diameter of the hose between the two greatly restricted meme flow). The Internet is a technology that, as Jeremy Riffkin points out, annihilates space-time. It allows the US and every other culture on earth to transmit memes to one another simply and rapidly regardless of their geographic distance (airplanes, satelites and the trans-Atlantic fiber-optic cable also annihilate space-time). Memes can now readily flow between the US and Europe. So that phenomenon, posting viral videos, has flowed into Europe. Now when I watch fail videos on YouTube, I see tons of Czech and Russian videos.

Finally, a note on fitness. What you are talking about is not fitness. Fitness has to do with contextual advantage. If a trait gives it's host an advantage, then that trait is adaptive. Adaptive traits make their hosts fit. The fittEST have the best chance of survival and reproduction; survival of the fittest. If someone is born a ginger, they aren't born that way BECAUSE they are fit, or BECAUSE it makes them fit. The trait itself, after birth, is either adaptive or maladaptive (or exaptive). Fitness DOES however have an effect on allele frequency. If dark moths get eaten less than white moths because they blend in better with sooty 19th century English industrial buildings, then the allele for being dark will increase its representation in the gene pool, while the allele for being white decreases; because the white ones are getting eaten before they can reproduce. But this doesn't mean that white moths cannot survive or that the white allele will disappear from the gene pool all together. So, again, the 100th generation ginger has nothing to do with happenstance and they aren't born that way BECAUSE of fitness. They're born that way because the ginger allele persists in the gene pool. Whether or not being a ginger is adaptive is determined later.

Quote:I think I can use your definition. I would prefer it dumbed down a bit so that people without more than a rudimentary education in evolution would understand it(thats one reason why I like my definiton). If you want to give a shot at dumbing it down a bit, I would appreciate it. If you don't I will go with it as is. I think a lot of atheists on this forum would reject my definition simply because I, a theist, wrote it and therefore it must be wrong. I think they would be more accepting of your defintion.

I honestly think that you should use "Descent with modification over time via selection," as your definition.

Descent = A traceable line of inheritance.
Modification = A mutation of the inherited replicator, either random or deliberate.
Over time = It is a continual process that can be traced on a timeline.
Via selection = The mechanism that determines which modifications are more often inherited.

The dumbing down I'm about to attempt is really going to turn what I originally wrote into an explanation rather than a definition.

Here goes...

Traits are inherited. Evolution is a process in which the most advantageous (adaptive) traits get selected for, and the most disadvantageous (maladaptive) are selected against. The more adaptive a trait is, the more it's inherited and the reverse is true for maladaptive traits. A trait is a phenotype; the combination of a replicator and the environment it was expressed in. Selection occurs not at the level of the replicator, but at the level of the phenotype. Every population has one or more replicator pools, the sum total of replicators in that population. Every population exists in a given environment. Selection occurs in the context of a replicator pool and in the context of a given environment. Replicators mutate, meaning that what constitutes an adaptive or maladaptive trait constantly changes because the phenotype is constantly changing. This means that over time, different traits are selected for. That leads to an array of changes within that population over time. These changes influence the evolution of other populations within that same environment (because the populations are in competition with one another) and they influence the evolution of other replicator types (because replicators are in competition not just with themselves, but with other replicators). The changes in other populations and other replicator types in turn influence the evolution of the original replicator pool. When a given population is split in two and separated by space-time (geography and communication being two examples) then changes begin to accumulate within both populations, which means that they start to become different from one another. This collection of changes is called drift. Drift, along with periods of sudden and rapid environmental change, can result in caldogenesis; the creation of clades. A clade consists of an ancestor and all of its descendants. Essentially, one becomes two or more. While mutations that are adaptive lead to an increase in their representation within the replicator pool, over time, the representation of mutations that are maladaptive either decreases, or reaches zero. When representation reaches zero, that mutation has become extinct.

Quote:I think a lot of atheists on this forum would reject my definition simply because I, a theist, wrote it and therefore it must be wrong.

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04-03-2013, 03:37 AM
RE: Defining evolution
(03-03-2013 08:57 AM)robotworld Wrote:  I'll give a very, very general definition?
Biological evolution refers to the change in allele frequency in a population over a period of time.

I prefer Phaedrus' definition. It's clear and easy to understand. Ghost's definition is very clear and specific, which I like as well, but might be daunting for some.

Also, another source of variation other than mutations: Processes in meiosis I such as crossing over (prophase I) and independent assortment (metaphase I).
Phaedrus gave a fine definition of biological evolution. When I told him I didn't want a definition that was exclusive to biology and he just repeated his biological definition...Phaedrus became annoying.
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04-03-2013, 10:12 AM
RE: Defining evolution
Here is a hint for any debate you come across in life, if you feel the need to provide your own definition for an established idea/concept/hypothesis/theory, you are probably doing it wrong.

“Science is simply common sense at its best, that is, rigidly accurate in observation, and merciless to fallacy in logic.”
—Thomas Henry Huxley
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04-03-2013, 10:31 AM
RE: Defining evolution
(04-03-2013 03:37 AM)Heywood Jahblome Wrote:  
(03-03-2013 08:57 AM)robotworld Wrote:  I'll give a very, very general definition?
Biological evolution refers to the change in allele frequency in a population over a period of time.

I prefer Phaedrus' definition. It's clear and easy to understand. Ghost's definition is very clear and specific, which I like as well, but might be daunting for some.

Also, another source of variation other than mutations: Processes in meiosis I such as crossing over (prophase I) and independent assortment (metaphase I).
Phaedrus gave a fine definition of biological evolution. When I told him I didn't want a definition that was exclusive to biology and he just repeated his biological definition...Phaedrus became annoying.
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04-03-2013, 01:46 PM (This post was last modified: 04-03-2013 01:51 PM by Heywood Jahblome.)
RE: Defining evolution
(04-03-2013 10:12 AM)TheBeardedDude Wrote:  Here is a hint for any debate you come across in life, if you feel the need to provide your own definition for an established idea/concept/hypothesis/theory, you are probably doing it wrong.
I want to use one of your guy's definition or modify my definition with your you guys input. Your criticism doesn't apply here. Also, there is nothing wrong with using your own definition if it is substantially correct. My definition included all the elements of an evolutionary process. There been some minor nitpicking of terms but it is substantially correct.

The biggest flaw in my original definition that you guys have exposed is the last sentence where I claimed evolution leads to an increase in diversity, complexity, and knowledge. I agree that evolution doesn't always lead to those things, but it can. It also can lead a decrease in those things so my original sentence was one sided. This is a perfect example of why I presented the definition to this forum. To expose the flaws in it.

Now if I asked an educated atheist on the street what is the explaination for the diversity and complexity of life, their response would surely be biological evolution(and they be right...in some sense at least). I don't think it is out of line to include a sentence that says something about the impact evolutionary processes have on reality.
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04-03-2013, 01:58 PM
RE: Defining evolution
Evolution has a certain definition because it describes what we observe in reality.
Are you observing something else ?
Are you observing another reality ?
Are you trying to create and define a non-biological structure that can mimic what we observe in evolution ?

We have computer models that attempt to mimic the weather.
Creating a computer model that mimics evolution would be very useful in teaching evolution.

I'm all for it.

But what I think you are really trying to get at is that the process of evolution can be "created" in a non-biological sense. And if it can be created by us, then surely a god can have his hand in the biological evolution.

This all comes down to the idea that you can't accept that human beings and all life for that matter weren't the product of some creation, in much the same way that a non-biological self evolving computer program must have had a programmer to create it in the first place.

A wooden chair has a carpenter therefore a tree must have a creator.
It doesn't work that way.

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04-03-2013, 02:33 PM
RE: Defining evolution
(04-03-2013 01:58 PM)Rahn127 Wrote:  Evolution has a certain definition because it describes what we observe in reality.
Are you observing something else ?
Are you observing another reality ?
Are you trying to create and define a non-biological structure that can mimic what we observe in evolution ?

We have computer models that attempt to mimic the weather.
Creating a computer model that mimics evolution would be very useful in teaching evolution.

I'm all for it.

But what I think you are really trying to get at is that the process of evolution can be "created" in a non-biological sense. And if it can be created by us, then surely a god can have his hand in the biological evolution.

This all comes down to the idea that you can't accept that human beings and all life for that matter weren't the product of some creation, in much the same way that a non-biological self evolving computer program must have had a programmer to create it in the first place.

A wooden chair has a carpenter therefore a tree must have a creator.
It doesn't work that way.

Maybe I will make that argument.....maybe not. You haven't heard my argument so your not in a position to claim you know what it is going to be about. This thread is about coming up with a definition of evolution that can be used in arguments. I would think many of you atheists would appreciate an argument made by a thiest that used YOUR terms and definitions.
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04-03-2013, 02:56 PM
RE: Defining evolution
(04-03-2013 01:46 PM)Heywood Jahblome Wrote:  
(04-03-2013 10:12 AM)TheBeardedDude Wrote:  Here is a hint for any debate you come across in life, if you feel the need to provide your own definition for an established idea/concept/hypothesis/theory, you are probably doing it wrong.
I want to use one of your guy's definition or modify my definition with your you guys input. Your criticism doesn't apply here. Also, there is nothing wrong with using your own definition if it is substantially correct. My definition included all the elements of an evolutionary process. There been some minor nitpicking of terms but it is substantially correct.

The biggest flaw in my original definition that you guys have exposed is the last sentence where I claimed evolution leads to an increase in diversity, complexity, and knowledge. I agree that evolution doesn't always lead to those things, but it can. It also can lead a decrease in those things so my original sentence was one sided. This is a perfect example of why I presented the definition to this forum. To expose the flaws in it.

Now if I asked an educated atheist on the street what is the explaination for the diversity and complexity of life, their response would surely be biological evolution(and they be right...in some sense at least). I don't think it is out of line to include a sentence that says something about the impact evolutionary processes have on reality.
Were you simply trying to describe it in your own terms, that would be one thing, but you were attempting to assign your own definition. That ends up in exactly what this thread (I guess since I have not read any of it) is about, definition debating.

Either use the accepted definition for a word, or use a different word. If you use or assign your own definition, you are making the water intentionally murky so that it becomes either A) unclear what you are arguing for B) unclear what anyone responding is arguing for or against C) or makes the definition intentionally ambiguous and/or weak in some aspect of it so as to set up a straw-man.

Someone educated in science is likely to say that the reason we have such biological diversity today is because of evolution. That is not because evolution leads towards complexity (often organisms will reduce complexity in favor of a simpler solution through time). The diversity and complexity of our ecosystems is a function of evolution plus other internal and external factors, such as environment, climate, volcanism, the Earth's magnetic field, earthquakes, tectonic rearrangement of lithospheric plates, and even celestial factors like variability in solar input and output, impacts from bolides, magnetic storms, etc.

The complexity and diversity in the biological system are a function of evolution + time + distances+ and the other aforementioned factors. It is easier to regard the whole process as evolution, but that is not entirely accurate. Now, if one were to apply the term of evolution more loosely, it could be argued that biological diversity is a function of the Evolution of the Earth (that would include tectonics and climate) and Cosmological Evolution (the cycle of stars).

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