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Author
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Topic: The Definition for the Theory of Evolution
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 1 of 216 (409101)
07-07-2007 11:18 AM
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Your opinion, Your Favorite
In the Basic Fundamentals of THE Debate (now open to anyone) we seem to have reached an impasse on what the definition for the theory of evolution is. The two basic opinions are:
(1) RAZD
Evolution is the (hereditary) change in species over time. This is viewed as being essentially the same as "descent with modification" and "the change in frequency of alleles in populations" and is supported by (among others) the Forum Definition and Berkley University definition. (2) Murkywaters
Message 87The theory of evolution, on the other hand, can be stated as “All the living forms in the world have arisen over billions of years from a single common ancestor which itself came from an inorganic form.” This can be equated with the commonly used terms “macroevolution” (used by evolutionist) or simply “theory of evolution” (used by creationists). For which there is apparently no specific cite for a basis that I can find.
The questions are: (A) which is the better definition from a the standpoint of the science of evolution, (B) what are the failings of each definition, and (C) what is your personally preferred (concise) definition. Thanks.
Biological Evolution Forum please. Edited by RAZD, : brevity and clarity, subtitle
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 8 of 216 (409142)
07-07-2007 4:54 PM
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Reply to: Message 3 by Modulous
07-07-2007 3:31 PM
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Re: my opinion, my Favorite
The first is a general overview of evolution, and the latter is a specific overview (ie, natural history). Neither is a definition of the theory of evolution.
The theory of evolution is a collection of mechanisms that describe how hereditary change in species over time happens. In other words you want a set of mechanisms to say how evolution occurs referenced in the definition.
quote:
Message 17 (near the end)
- change in species over time,
- mutation as an observed fact,
- natural selection as an observed fact, and
- some other minor mechanisms such as genetic drift and horizontal gene transfer by viruses and the like.
That it does NOT involve
- sudden large scale change or
- sudden appearance of whole new features or abilities.
Would that help? (those were my stipulations for microevolution). Thanks.
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| This message is a reply to: | | | Message 3 by Modulous, posted 07-07-2007 3:31 PM | | Modulous has replied |
| Replies to this message: | | | Message 12 by Modulous, posted 07-07-2007 6:22 PM | | RAZD has replied |
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 9 of 216 (409144)
07-07-2007 5:05 PM
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Reply to: Message 7 by subbie
07-07-2007 4:43 PM
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Re: my opinion, my Favorite
How about something like: The theory of evolution is Life changes over time, due to hereditary mutations, natural selection, population dynamics, genetic drift and horizontal gene transfer by viruses and the like. Thanks.
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| This message is a reply to: | | | Message 7 by subbie, posted 07-07-2007 4:43 PM | | subbie has replied |
| Replies to this message: | | | Message 10 by subbie, posted 07-07-2007 5:27 PM | | RAZD has not replied |
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 17 of 216 (409181)
07-07-2007 9:04 PM
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Reply to: Message 12 by Modulous
07-07-2007 6:22 PM
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Re: my opinion, my Favorite
I would say it includes natural selection, hereditary variation, neutral drift and epigenetics to name a few but I would be more keen to draw a line between the phenomenon and the theory that explains the phenomenon. Would epigenetics cover the ground of evo-devo too? This seems to be an emerging aspect critical to how some (not all) features develop. It also seems a bit "technese" for a common definition (although that was not in the original specs). I was also thinking of including something regarding the effect of changes in the environment, and this would cover that. Thanks.
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| This message is a reply to: | | | Message 12 by Modulous, posted 07-07-2007 6:22 PM | | Modulous has not replied |
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 18 of 216 (409187)
07-07-2007 9:20 PM
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Reply to: Message 16 by Wepwawet
07-07-2007 8:48 PM
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Re: Please turn to The Book of Darwin: Chapter 1, Verse 1
The Theory of Evolution is the collective scientific understanding of developmental biology that begins with Darwin's Theory of Descent with Modification through Natural Selection ... ... adds the modern synthesis (with genetics), and is flavored as necessary by new theoretical mechanisms and phenomena... That would be some grand unified synthesis theory. Interesting approach. The only caveat that I have is that it doesn't necessarily exclude aspects that some people have preconceived as being necessary, like extremely long periods of time or a single common ancestor back at the start of life. Enjoy.
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| This message is a reply to: | | | Message 16 by Wepwawet, posted 07-07-2007 8:48 PM | | Wepwawet has not replied |
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 76 of 216 (409571)
07-10-2007 9:36 AM
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TOPIC please.
What I am looking for is a collection of definitions and brief discussion on the merits. Not extended dialogs. So far there is not much to advance as a general statement of the definition other than what is covered early in this thread. So far I have:
Life changes over time due to hereditary variations, genetic mutations, population dynamics, neutral drift, natural selection, environmental changes, epigenetics and similar mechanisms for introducing and selecting changes within populations. Is there anything else to add or detract from that?
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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What is your definition of the theory of evolution?
So what is your definition? What needs to be included and what is explained by the theory? Thanks
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| This message is a reply to: | | | Message 78 by Wounded King, posted 07-10-2007 12:02 PM | | Wounded King has not replied |
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Re: More drift from the topic ...
Evolution is a change in allele frequencies. If you think you can give me an example of evolution without allele frequencies changing, let us know. Ah, but what is that theory of evolution eh? Are there any scientific sources of definition for the theory that you know (like the Berkeley and the U of Mich definitions)? Whether Ray is mistaken or not is irrelevant in the end: it doesn't mean we need to stop talking about what the real definition of the theory of evolution involves. Enjoy.
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| This message is a reply to: | | | Message 94 by Dr Adequate, posted 07-13-2007 5:26 PM | | Dr Adequate has not replied |
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 108 of 216 (410390)
07-14-2007 6:05 PM
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Reply to: Message 103 by Modulous
07-14-2007 12:41 PM
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A different approach?
As Laplace may have famously said 'Sire, I have not needed that hypothesis.' The principle of parsimony, or Occam's razor.
There are many valid definitions on what the theory actually is. True, but then what are the common elements, and what can be discarded as unnecessary for defining how evolution operates -- and why?
- hereditary mutations,
- change in frequency of alleles in populations,
- natural selection,
- population dynamics,
- genetic drift (or neutral drift),
- environmental changes,
- epigenetics (the study of how genes produce their effect on the phenotype of the organism),
- evo-devo (a branch of biology investigating the links between evolution and the development of different organisms),
- punctuated equilibrium,
- horizontal gene transfer by viruses and bacteria,
- many generations,
- billions of years,
- common ancestry (general),
- from a single common ancestor,
- increased complexity,
- from an inorganic form,
- produces new “Kinds” (forms),
- produces greater information content,
- absence of god,
- etc.
(feel free to add any ... both evolutionist and creationist) I think we can all agree for instance that "from an inorganic form" is unnecessary as that is covered by abiogenesis and it only deals with one point in time, while evolution would apply to the whole continuous spectrum of life. I think we can also say that items like "increased complexity" and "greater information" need to have a method to measure them in order for the relative differences to be compared. I also do not see why increases are necessary either -- in some cases a simpler solution is better. Genetic definitions are problematic for applying to fossil evidence, so there it is easier to talk about hereditary traits -- the physical similarities and the subtle changes to the parts of the fossils over time. It seems to me that speciation is a critical element of the theory -- a newly made barrier that divides a population into two or more daughter populations -- and while the two (or more) daughter populations do have different frequencies of alleles from each other and from their parent population, changing frequencies doesn't imply that speciation is necessary. Without speciation there would only be one species on earth - cyanobacteria. Enjoy.
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| This message is a reply to: | | | Message 103 by Modulous, posted 07-14-2007 12:41 PM | | Modulous has not replied |
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 110 of 216 (410393)
07-14-2007 7:21 PM
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Reply to: Message 11 by Modulous
07-07-2007 6:14 PM
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Synthetic theory examples
I suppose you could define the synthetic theory like this site does:
quote:
Synthesis of Mendelian genetics and Darwinian selection into a modern theory of evolutionary change.
But that doesn't really define anything, it's saying how the theory is derived but not what it is. It also lists:
quote:
Evolution: Any change in gene frequency from one generation to the next. 4 Forces of Evolution:
Mutation, Gene Flow, Genetic Drift, Natural Selection.
And you would need to put all these together. Your other link has similar problems:
Or this one:
quote:
[The Synthetic Theory is] essentially a combination of Charles Darwin's concept of natural selection, Gregor Mendel's basic understanding of genetic inheritance, along with evolutionary theories developed since the early 20th century by population geneticists and more recently by molecular biologists
And when I look at the next page from that one I get:
quote:
The biological sciences now generally define evolution as being the sum total of the genetically inherited changes in the individuals who are the members of a population's gene pool. It is clear that the effects of evolution are felt by individuals, but it is the population as a whole that actually evolves. Evolution is simply a change in frequencies of alleles in the gene pool of a population. For instance, let us assume that there is a trait that is determined by the inheritance of a gene with two alleles--B and b. If the parent generation has 92% B and 8% b and their offspring collectively have 90% B and 10% b, evolution has occurred between the generations. The entire population's gene pool has evolved in the direction of a higher frequency of the b allele--it was not just those individuals who inherited the b allele who evolved.
This is the common frequency of alleles definition, heavy on genetics, light on natural selection, and mute on speciation (or even the question of what a species is). Enjoy.
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| This message is a reply to: | | | Message 11 by Modulous, posted 07-07-2007 6:14 PM | | Modulous has replied |
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Re: A different approach?
We can reword it then as increased interdependence and gain the understanding that increased complexity naturally follows when systems of atoms {simplistic WRT organic life} whose bonds {attributable to the electromagnetic force alone} become molecules which in turn follow these same bonding rules to become organic {carbon bearing} and up the chain of interdependence to become amino acids,proteins etc... I would still need a way to measure it to compare individuals and species, and I would also argue that in some cases a return to a less interdependent molecule\whatever cannot be ruled out, especially if it takes less resources and energy to facilitate survival. If evolution can go either way, then this is not a necessary element. Another thing I found on a following page from one of Modulous' links was: http://anthro.palomar.edu/synthetic/synth_2.htm
quote:
Hardy, Weinberg, and the population geneticists who followed them came to understand that evolution will not occur in a population if seven conditions are met:
1. mutation is not occurring
2. natural selection is not occurring
3. the population is infinitely large
4. all members of the population breed
5. all mating is totally random
6. everyone produces the same number of offspring
7. there is no migration in or out of the population
Maybe this can help us define what is necessary in the definition. Enjoy.
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Re: Synthetic theory examples
This is the common frequency of alleles definition, heavy on genetics, light on natural selection, and mute on speciation (or even the question of what a species is). Speciation is one of the things that the theory of evolution explains, it's not part of the explanation. How does 'change in frequency of alleles in populations' explain speciation without introducing additional elements? Enjoy.
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 117 of 216 (410483)
07-15-2007 11:23 AM
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Reply to: Message 113 by Modulous
07-15-2007 5:43 AM
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Re: Synthetic theory examples
The listed description is not a definition of 'The theory of evolution' it is a definition of 'evolution'. The two are different like gravity and relativity are different. You mentioned earlier you think speciation is important - but species is an entirely arbitrary term, so I don't think speciation is important. After all - different biologists investigate the world using different definitions of 'species'. That is one of the problems with evolution -- the word is used to mean different things. What evolution is does need to be part of the theory for how evolution occurs, and how it occurs needs more than just what it is. It's not so much that speciation needs to be included, but that the theory can explain speciation - especially where it involves separation of parent populations into different daughter populations.
Still - the site does go into it here. Yes, and it also says
quote:
When the populations are in dissimilar environments, environmental stresses are often not the same. As a result, nature selects for different traits existing within the gene pools of the populations.
Thus the dissimilar environments become necessary for this kind (adaptive radiation) of speciation (also known as non-arbitrary speciation). And
quote:
Descendant generations experience continuous spontaneous mutations and new directions of natural selection as the environment changes.
So different environments are also required for this kind (successive) speciation (also known as arbitrary speciation as the divisions are relatively arbitrary). We also see environment\ecology as the driving difference between stasis and non-stasis evolution in punk-eek:
quote:
The punctuated, or rapid change periods, were presumably the result of major environmental changes in such things as predation pressure, food supply and climate. During these times, natural selection can favor varieties that were previously at a comparative disadvantage.
This of course is where phenotype (the appearance of an organism resulting from the interaction of the genotype and the environment) comes into the picture.
Any theory can be 'defined' in a number of different fashions. The theory of evolution can be defined as an amalgam of many theories of biological change - or it can be defined by listing the main theories or even by briefly explaining the ins and outs of each of the hypotheses. Yes, this would be similar to the "standard model" in physics, an amalgam of theories that are picked up as they prove useful and dropped as they are invalidated. I have trouble with calling this a theory, as such an amalgam cannot be falsified - it just morphs as the member theories move in and out - without, of course, every single supporting theory being invalidated. So maybe we should say there is a "standard model" of evolution, rather than an overall theory. Enjoy.
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| This message is a reply to: | | | Message 113 by Modulous, posted 07-15-2007 5:43 AM | | Modulous has not replied |
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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Message 118 of 216 (412579)
07-25-2007 1:07 PM
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More thoughts ...
First, to be a "general" theory of evolution it has to be applicable to studies that cover the range of evidence in the science of biological evolution, from the small changes within breeding populations (beak changes in Galapagos Finches) to the large changes over time seen in the fossil record (the development of new features). This latter portion makes a genetic definition difficult, as the features fossilized are due to (genetic and other) epigenetic factors. Hereditary traits can be observed and tracked without knowing the epigenetic basis. Second, evolution is not a "productive" process, rather it is a "feedback response" process, an endless "do while" loop under changing ecological conditions (where the only escape from the loop is individual death and species extinction). A simplistic "program" for the feedback process would be something like: (1) Take Population {A} with m existing inheritable
variations and n individual organisms where
n = SUM(m x # organisms with m)
(2) Let p = n
(3) Do while organism = 1 to n
(a) Does organism breed?
(b) If NO let p = p-1, go to Next variation
(c) Go to Next variation
(4) Let Population {A'} = the breeding remainder of
Population {A} with total p remaining organisms,
where
m' = remaining variations in Population {A}
and p = SUM((m' x # OLD organisms with m')
(5) Let {A''} = new offspring of Population {A'},
where
p' = SUM(m' x # NEW organisms with m') for
the offspring that inherit their traits
from the parent population, and
q = SUM(m* x # NEW organisms with m*) for
the offspring with new variations (due
to mutations)
(7) Form Population {B} from remaining organisms
of Population {A} plus offspring
{B} = {A'} + {A''}
(8) Set {A} = {B}
(9) Set n = p + p' + q
(10) Go to (2) Note "n" and "p" would represent the total organisms not the number of allele variations. The number of alleles would be represented by m, m' and m*. You could get more detailed about tracking allele frequencies and the number of times each organism breeds (and whether the offspring inherited which alleles), but this should give the basic idea of the feedback mechanism. The response part of the mechanism is whether the organisms survive to breed, and this depends on the relative changes in ecological factors (predator prey relations, nutrition & disease factors, environmental change factors, etcetera). Thoughts?
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RAZD
Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: 03-14-2004
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OFF TOPIC
As noted you are off topic here.
...if it is a universal constant or not; if it is rendered superfluous by the 'seed' factor. I suggest you start a thread on this so you can have your position well defined and allow people to refute it without affecting this thread with the inanity required. Thank you.
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| This message is a reply to: | | | Message 124 by IamJoseph, posted 07-30-2007 8:52 AM | | IamJoseph has replied |
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