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Author | Topic: How do you define the word Evolution? | |||||||||||||||||||||||||||
CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
As I've seen from the previous posts there are different definitions of evolution.
I think Kerkut made a good attempt at a definition in "Implications of Evolution", 1960 where he distinguished between the special theory and the general theory.
There is a theory which states that many living animals can be observed over the course of time to undergo changes so that new species are formed. This can be called the ‘Special Theory of Evolution’ and can be demonstrated in certain cases by experiments. On the other hand there is the theory that all the living forms in the world have arisen from a single source which itself came from an inorganic form. This theory can be called the ‘General Theory of Evolution’ and the evidence that supports it is not sufficiently strong to allow us to consider it as anything more than a working hypothesis. Coyne gave a definition in "Why Evolution is True", 2009, which is very similar to Kerkut's definition of the ‘General Theory of Evolution’.
Life on earth evolved gradually beginning with one primitive speciesperhaps a self-replicating moleculethat lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species; and the mechanism for most (but not all) of evolutionary change is natural selection. John Endler in "Natural Selection in the Wild" 1986 says,
Population geneticists use a different definition of evolution: a change in allele frequencies among generations. This meaning is quite different to the original [and] is roughly equivalent to microevolution. Unfortunately [this] often results in an overemphasis on changes in allele frequencies and an underemphasis (or no consideration of) the origin of the different alleles. The terms micro- and macroevolution were coined by evolutionist Russian Entomologist Yuri Filipchenko in 1927 in his German language work, "Variabilitt und Variation". Kirk Dunstan discussed micro- and macro- and proposes definitions;
- Microevolution: genetic variation that requires no statistically significant increase in functional information. [edit] http://p2c.com/...roevolution-vs-macroevolution-two-mistakes- Macroevolution: genetic change that requires a statistically significant increase in functional information. He says "Both statistical significance and functional information are already defined in the literature. We also have a method to measure evolutionary change in terms of functional information, so we are ready to move on, ..." According to this definition there is a qualitative difference between the two and so macroevolution does not simply arise from microevolution continued over a long time. So if we are talking about Darwin's Theory of Evolution or its modern derivatives I think Coyne's definition is satisfactory and equivalent to Kerkut's ‘General Theory of Evolution’. The definition "a change in allele frequency in a population over time" refers to the specific subset of evolutionary theory used in population genetics, a form of microevolution, and should not be used for "the Theory of Evolution", or "[neo-]Darwinian Evolution". Edited by CRR, : reference added
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
Dunstan's definition is very different because it is referring specifically to micro-vs macroevolution, i.e. it is not intended as a definition of evolution in general.
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
Kirk Durstan
Ph.D. Biophysics, 2010, University of GuelphM.A. Philosophy, 1997, University of Manitoba B.Sc. Mechanical Engineering, 1979, University of Manitoba B.Sc. Physics, 1976, University of Manitoba Has also completed eleven graduate-level courses toward a Masters degree in Theology. Academic Publications Science Durston, K.K., Chiu, D.K.Y., Wong, A.K.C., Li, G.C.L. (2012), ‘Statistical discovery of site inter-dependencies in sub-molecular hierarchical protein structuring’, EURASIP Journal on Bioinformatics and Systems Biology 2012, 2012:8Durston, K.K.; Chiu, D.K.Y. (2011), Chapter 5. Functional Sequence Complexity in Biopolymers. In The First Gene: The Birth of Programming, Messaging and Formal Control, Abel, D. L., Ed. LongView Press—Academic, Biol. Res. Div.: New York, N.Y., pp 117-133. Durston, K.K., Chiu, D.K.Y., Abel, D.L., Trevors, J.T. (2007), ‘Measuring the functional sequence complexity of proteins’, Theoretical Biology and Medical Modelling, 4:47, 1-14. Durston, K.K., Chiu, D.K.Y. (2005), ‘A functional entropy model for biological sequences’, Dynamics of Continuous, Discrete and Impulsive Systems: Series B Supplement, University of Waterloo. Edited by CRR, : Publications added (science only) Edited by CRR, : No reason given.
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
So, not even one of the definitions of evolution addresses the formation of the Universe, the formation of stars; the formation of earth, the age of the earth; or anything like that. Of course not. This is after all in the Biological Evolution forum. It also doesn't address the evolution of the motor car. But if you really want to extend it to all those things then Evolution=change over time, and then even a melting ice cube is evolving! p.s. Sarcasm. In case you missed it.
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
You're pretty obsessed about a one letter typo. Get over it.
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
Actually, that's how all those professional creationists define evolution. According to them, a melting ice cube is part of evolutionary theory. OK, so you did miss the sarcasm, even though I flagged it.
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
So what's your definition of evolution?
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
...shouldn't there be a complete trail of the different changes visible today in the fossil record? Which is what Darwin said would exist. Yes Darwin did say there should be and wondered why we didn't find them. He suggested that the extreme imperfection of the fossil record was the reason. The fossil record has been explored extensively since then and the transitional fossils are still not there. Instead the fossil record shows sudden appearance and disappearance with stasis in between. This is what Gould referred to as "the trade secret of paleontology" and the reason he and Eldridge developed the theory of Punctuated Equilibrium. Darwin argued in "Origin of Species" that even in a stable environment there should still be evolution since there was always competition within the species for food and reproduction. However there has never been extensive periods of stable environment and even if the abiotic environment was stable the biotic environment would be changing as predator and prey adapted to counter each other. So the "no change because they're already so well adapted" argument fails. The continued lack of transitional forms in the fossil record is a slap in the face for [neo-]Darwinian evolution.
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
From your reference;
A recent example from the news is the discovery of the fossil species Tiktaalik roseae. Tiktaalik is a transitional form in the evolution of vertebrates on four legs. Ahlberg and Clack (2006) describe the importance of the discovery: It demonstrates the predictive capacity of palaeontology. The Nunavut field project had the express aim of finding an intermediate between Panderichthys and tetrapods, by searching in sediments from the most probable environment (rivers) and time (early Late Devonian). Second, Tiktaalik adds enormously to our understanding of the fish—tetrapod transition because of its position on the tree and the combination of characters it displays.Per Erik Ahlberg and Jennifer A. Clack (2006) "Palaeontology: A firm step from water to land," Nature 440:747-749 Tiktaalik has turned out to be an epic fail for evolution. After Tiktaalik was found fossil footprints were found that predated it in the Zachelmie Quarry. This shows that the data on which the prediction was based was wrong and hence the finding of Tiktaalik was simply fortuitous, and destroys the claim of predictive capacity. The above wording suggests, and I can remember it being promoted as, not as just an intermediate form but as an actual intermediate. Since footprints predated it, it couldn't have been an intermediate after all. There are problems with many of the claimed sequences of transitional fossils.The palaeontologist David Raup wrote: ‘The record of evolution is still surprisingly jerky and, ironically, we have even fewer examples of evolutionary transition than we had in Darwin’s time. By this I mean that the classic cases of darwinian change in the fossil record, such as the evolution of the horse in North America, have had to be modified or discarded as a result of more detailed information. What appeared to be a nice simple progression when relatively few data were available now appears to be much more complex and less gradualistic. So Darwin’s problem has not been alleviated.’ D.M. Raup, ‘Conflicts between Darwin and paleontology,’ Field Museum of Natural History Bulletin 50:22, 1979. Similarly whale evolution is looking very problematic since (a)Pakicetus was shown to be fully terrestial instead of the otter like creature originally postulated, and (b)finds early fossils of fully formed whales has closed the evolutionary window to about 1 million years which is impossibly short. But here's the rub, this thread is " How do you define the word Evolution? ". Where is your definition?
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
Just saying "You made that up" is not an Adequate answer.
If you have read "Origin of Species" you must have missed that bit. But here's the rub, this thread is " How do you define the word Evolution? ". Where is your definition?
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
I don't think anybody deserves a reply until they have answered the original question, "How do you define the word Evolution?"
[edit] RAZD has given a fairly lengthy definition and I am considering my reply. Edited by CRR, : as noted
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
After reading previous discussion and having a good think on the subject I think the best definition of evolution overall is a slight modification of Kerkut’s;
Evolution is the theory that all the living forms in the world have arisen from a single source which itself arose naturally from an inorganic form. The key elements of this are abiogenesis and ascent from a last universal common ancestor (LUCA). Coyne, in his definition adds, the mechanism for most (but not all) of evolutionary change is natural selection.. But note that this expands it by specifying a mechanism. Mutation, selection, genetic drift, punctuated equalibrium, etc., are all mechanisms of evolution but should not be confused with the definition of evolution itself. LUCA is considered to be a simple microbial life form with a minimal genome and the mechanisms of evolution have added the genetic information to produce complex life forms including man. Hence I say ascent rather than descent in my definition. The definition from population genetics; a change in allele frequency in a population over time; is unsatisfactory because it focusses on only a part of the whole scope of evolution. Now I know that some people will object to including abiogenesis in the definition but I think it is an essential part of the thinking of most evolutionary biologists and inseparable from evolution.
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
Reasonable comments, caffeine. Thank you. I don't think any definition will satisfy everyone. I was trying to give a concise definition, including only what was necessary, excluding the non-essential.
I think it can allow for multiple independent life forms having originated abiotically but only one, which could have been a chimera, became the ancestor for all living things today. I believe the prevailing opinion today. It also doesn't exclude change, in fact a great deal of change would have been necessary to produce all of today's life forms from LUCA. But it does leave room for a discussion about whether all change is evolution. I included abiogenesis specifically to exclude the position that life was created and evolved from there. Kerkut explicitly included it and I think Coyne also included it by his reference to a "self replicating molecule". It might not exclude everyone in the ID movement, I think at least some would accept an abiotic origin of the first life and most seem to accept evolution over millions of years.
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
I think the term abiogenesis was coined by Thomas Huxley after Pasteur disproved spontaneous generation and formulated the Law of Biogenesis. At that time there was no intention to separate abiogenesis from evolution.
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CRR Member (Idle past 2273 days) Posts: 579 From: Australia Joined: |
While evolution does rely a lot on luck and chance the theory proposes rather more than this. Natural selection filters what comes to it to produce non-random results. Your definition does not describe either what evolution does, and has done, or how it works.
In my definition I have tried to say what it does rather than how it works. Some people are ready to criticize without providing a definition of their own. Feel free to comment on my definition at Message 87; EvC Forum: How do you define the word Evolution?
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