Definition of Evolution

After reading many responses, I began to wonder how it can be so difficult to define evolution in a way that satisifies both parties.Let me offer my general evolution definition. Hopefully, the simplicity will appeal to all."The change in a population across generations"This definition doesn't specify at which level the change is taking place.
To address the connotation that evolution has in these discussions, I'll modify the simple version a bit."Change in a population's genetic traits across generations"This definition is applicable to both flavors: micro- and macroevolution (if you do believe a distinction is needed).Microevolution: Genetic changes occurring within a species that do not result in the formation of a new species.Macroevolution: Genetic changes occurring in a population that allow for the creation of a new species.The definitions simply say what it is, not how or why it occurs. While it is almost always implied that evolution refers to evolution of humans from less complex forms of life, this definition contains no explicit claims of saying all life evolved or at what time life started to evolve. Hopefully, simple definitions can be appreciated by both sides of the argument?
(By the way, I do accept that humans evolved to what we are now.)The question now should be:
"Can the accumulation of changes (over long periods of time) in genetic traits in a population or population(s) result in homo sapiens?"EDIT: Also, just in case it hasn't been said, evolution does not require that changes have to be positive. That's more with natural selectionEdited by Xaruan, : No reason given.

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No real objection at all, especially seeing as this is virtually identical to my "extremely liberal" definition of evolution "according to (my) terms" you quoted in Message 1:

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Evolution is the change in hereditary traits within populations of species over time, ...

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Now we can quibble that not all genetic traits are hereditary traits (the genetic change needs to be in the genes passed to the next generation, while some mutations occur during growth and only affect the development of the existing organism), and we can quibble over the minor distinction between "generations" and "time" ... but overall they are basically interchangeable.

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Right, they are pretty much identical. The only difference is my exclusion of the word species and use of the term "generations" rather than "time". I thought the exclusion of "species" would keep the definition a little more general but equally valid. My opinion still stays that the real question is to what extent evolution occurs.By the way, your original definition wasn't liberal at all. The definition doesn't say one side's argument is correct or not. (EDIT: That particular segment of your definition was nearly identical to mine.)I like how someone (in the last few posts) finally said that defining something shouldn't degenerate into arguing over what the theory implies.Once people all decide on a definition, this thread should be locked. Is there any reason why other arguments are going on?I also disagree with the renaming of the thread "Prerequisites for Defining Evolution". The definition iteself takes no more than one or two sentences. Does there need to be a thread on what we have to decide before deciding on a definition? With all due respect, I think a thread name "Prerequisites for Defining Evolution" makes little sense and will cause endless confusion with no forseeable conclusion.Edited by Xaruan, : No reason given.

Isn't this the thread about "Definition of Evolution" not the thread about "Proving the Theory of Evolution"? Seriously, threads have topic titles for a reason.

RAZD, that was a good post you linked to.ev·o·lu·tion
3. Biology.
a. Change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.
b. The historical development of a related group of organisms; phylogeny.That's a pretty good definiition. Normally, I would say the strict definition of evolution should avoid explicitly stating "resulting in the development of new species", but because I assume everyone accepts that natural slection occurs, the development of new species becomes the heart of the matter. If one takes to time to consider this definition, it still allows for some creationists to believe in the theory of evolution. I have known some creationists to believe that evolution (by this definition) can occur but started occurring only after God created the Earth. So this definition does not disallow creationism. (Like I said, the question is to what extent evolution occurs).If people want a definition of evolution that disallows the very literal interpretation of Genesis (6 days, humans were made as is) I'll try to provide one."Evolution involves the heritable changes in a population.Evolution implies how viruses and single-celled organisms were formed: components came to exist through an increase in molecular complexity. Atoms form molecules, which in turn form more complex molecules, such as RNA, DNA, amino acids, proteins, etc. Driving forces for the increase in complexity are explained through principles in physics and organic chemistry (such as steric hindrance and desire for a stable conformation/bond).Evolution uses the principle of natural selection--where traits aiding survival and/or reproduction are more likely to be passed on to future generations--to describe how some characteristics of a population continue while others die out.Heritable changes occur seemingly randomly and are not necessarily favorable, indicating not all changes will remain within a population. Drastic changes in populations are (typically) only visible over a significantly large time scale.Further implications include the increase in cell size and complexity (eukaryotes), the development of multicellular organisms (plants, fungi, animals), and the eventual emergence of humans. The necessary accumulation of heritable changes needed to account for the current number of species and their complexity could not have been reached in just the last 10,000 years."I think that's an adequately complex definition that will disallow compatibility with young-earth creationism
Feel free to quote and edit if you feel modifications are in order.orIf you prefer the more general definition, say so.Edited by Xaruan, : No reason given.Edited by Xaruan, : No reason given.

I think anyone who has learned about genetics can accept that mutations or changes in genetics occur and they can be passed on. There is no denying that. If we use the general definition of evolution that I proposed "Change in the genetic traits of a population across generations", then it follows that anyone (evolutionist or creationist) who knows basic high school biology cannot possibly deny that evolution occurs. However, even with this definition, creationists still believe evolution did not start before Adam and Eve and evolution does not explain the emergence of humans. That's what I am meaning when I say extent. If both sides believe evolution occurs (according to the general definition), the debate comes down to the following:
1. Does evolution occur to a degree that can cause the formation of a new species?
2. Did humans come into existence because of evolution from less complex life forms?
3. And is that possible within the time scale given by creationists?My use of extent includes time scale and intensity. Extant just means something is currently existing, so I'm not sure why you brought that up.Edited by Xaruan, : No reason given.

Revision #3.Evolution with common descent
"Changes in a population's genetic traits across generations, which has resulted in the present diversity of species having originated from a common ancestor"Certainly, a definition is not meant to describe all the aspects of evolution, which is why I kept my original definition short and to the point. And the distinction of micro vs macro is more for the creationists' benefit. I may be going out on a limb, but I'm assuming most evolutionists are of the opinion microevolution implies macroevolution and that to make the leap from one to the other is without difficulty. Edited by Xaruan, : No reason given.

Nothing wrong. I just stumbled upon this site, and saw this thread. Read the first few pages, read the last page, and I came to the conclusion that people were still arguing over how to define evolution (in this thread). So, I decided to put in my $0.02 by offering a pretty basic definition, not unlike yours.Edited by Xaruan, : No reason given.

You summed it up nicely.
I'm going to repost the same quotes, because no one should overlook them.

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Many people are confused about the difference between a definition and an explanation. That's why we often see incorrect "definitions" that describe how natural selection works. This is wrong. In order to be useful, a definition has to enable us to distinguish examples of evolution from non-evolution but the definition should be neutral with respect to how evolution occurs. It should not distinguish, for example, between Lamarckian evolution and Darwinian evolution even though we know that one of these explanations is incorrect.

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The amazing thing about the minimal definition of biological evolution is that it doesn't carry any baggage concerning the history of life or its future. As soon as we try to define evolution in terms of the historical record, we run into all kinds of problems because we confuse evolution as a process with evolution as a history of life.

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Edited by Xaruan, : No reason given.