I want to start this topic in order to discuss what specifically is meant by the term, evolution.
Does evolution have a narrow definition or a broad definition?
Is there a consensus among most scientists as to what this term means? Why is there even a debate over what evolution is and is not?
The Dictionary defines evolution as:
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.
Personally, I don't understand much of science myself, although I am becoming better able to appreciate arguments and debates on a surface level while not understanding the complexities of them.
The definition you provided is pretty much the standard one. Wording may vary, emphasis may vary, and the definition leaves out a lot of details. And therein lies the rub: the devil is in the details. The deeper you go, the more detail is revealed, and that is where discussion, argument and disagreement arise - among scientists, at any rate.
Why is there even a debate over what evolution is and is not?
There isn't. Not among biologists (and ALL of the life sciences disciplines). Only those who, for whatever reason, dislike the non-scientific implications - or at least what they see as the implications - argue over what it is and is not. Most of the threads on this board are geared to correcting - sometimes with a hammer - misconceptions by non-biologists. And in-house over the details.
The problem is that evolution is such a large concept that it can't be defined in a pithy, one-sentence toss-off without doing it a grave disservice. The definition you provide focuses on natural selection, but that ignores all other selective factors such as sexual selection and all non-selective factors such as neutral drift.
The pithy definition I've heard is that evolution is the shifting of allele frequencies in a population over time. This definition, however, doesn't say anything about where new alleles come from, if at all, how they arrive if they do, and what happens to current ones that exist. Now in some sense, evolution doesn't care. Just as we don't want to restrict ourselves to natural selection, we don't want to necessarily restrict ourselves to mutation...especially since that depends upon a definition of "mutation." Is infection "mutation"? There's a good reason to say yes, but I can understand why one might want to make a distinction between genetic material coming in from external organisms and genetic material being altered inside the individual organism.
Note, this is not unique to evolution. Gravitational theory is not nearly sufficiently summed up by F = Gm1m2/r2. That doesn't explain where gravity comes from (which we still don't know), if it can be manipulated, etc. There's a reason that people write volumes upon volumes on the subjects of gravity and of evolution. They can't be reduced without losing something in the process.
Rrhain Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.
quote: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.
This definition is a little problematic, because evolution and natural selection are not completely linked concepts. Natural selection typically refers to the difference in survival capacity between phenotypes (or, outward characteristics). Sexual selection, one possible alternative method of evolution, refers to the difference in reproductive success between phenotypes. Additionally, mutation and other random and quasi-random factors can cause evolutionary changes. Intermixing of once-separated populations can also alter the genomes of the net generation.
So, evolution is, as the simplest and most commonly used definition states, "descent with modification." Natural selection is one (probably the most common) mechanism by which evolution can occur.
evolution: the biological changes in living things.
Technically, no. Specific living things don't evolve. The smallest unit that could evolve is a population.
but wait..doesn't non living things evolve? doesn't the stars have an evolution?
Stellar evolution is directional. Biological evolution is not.
evolution: the changes in the universe of all things in it, by way of adaption, based on the conditions that it exists.
i must admit, i cannot further define evolution. it is beyond my ability.
The word "evolution" is thrown around way too much, me thinks. People go and see the movie 'Underworld: Evolution' and they think they should get a phd on biological evolution.
Even writers of the Star Trek series have it totally wrong. In one of the episodes of Star Trek: Enterprise, the ship encounters a planet where two sentient species have survived the "evolutionary process". One of them is technologically advance enough to travel to other star systems while the other still in their stone age. But wait, there's a catch. "Evolution" has decided that the technologically advance species must go in order for there to be room for the stone age species to grow. So, this whole race is dying. Doctor Flox, being a genius that he is, finds a cure for this genetic disease. But he convinces Captain Archer not to give the cure to the dying race because "Evolution" has made a choice and "who are we to question it?" So, the Enterprise leaves orbit with the cure leaving behind 2 billion dying people.
What kind of moron wrote that story? The bastard must have thought evolution is some kind of deity.
i must admit, i cannot further define evolution. it is beyond my ability.
You've yet to start defining it! You're opening brainstorm
evolution: the biological changes in living things
is so loose that it would include changes in blood sugar levels, antibody response to infection, getting goosebumps when you're cold and getting pregnant! Do you really mean that you consider these examples to be evolution? It's as bad as Behe's definition of science which takes in Astrology.
Given that this is obviously so much marsh gas, the causes of your "biological changes" are irrelevant, since you're using tem to list the causes of something that isn't evolution.
If you read around a bit on the intrnet, you may gather enough information to refine your definition, however, bear in mind that
so i feel it is true
doesn't really cut the mustard.
I think what Phat had in mind is what science defines as evolution.
Leave out the stars - that sort of evolution has an entirely different meaning and, as such, has an entirely different definition. You're trying to define the word not the concept.
i thought the question was, what is the TRUE definition of evolution.
do stars evolve? has the earth evolved? man has evolved? the ocean currents have evolved? the universe has evolved?
if it evolves..isn't it evolution?
evolution then would encompass more than the biological sense in a "true" definition.
a digression based on this observation:
the same elements that make up the earth and universe are present in the make up of biological things, and the same forces (strong force etc) are holding together these elements in biological things, as it holds things together in non biological things.
the term "alive" is applied only to the biological things, because of the complexity of the environments that the elements exist in.
ie: if you take biological ,material and examine its base composition, what is found? carbon..i dunno the rest. carbon based i do know.
now, the arrangement of the carbons and other elements work together in a complex fashion, therefore, it is "alive"
under this observation, the laws that apply to non living things, apply to living things. but must be scrutinized by individual environments (conditions).
so to say evolution of biological things is the most common understanding of the word evolution not a lie, but that a true definition of evolution would be attributed to things that "evolve"
Edited by tesla, : the=then
Edited by tesla, : No reason given.
keep your mind from this way of enquiry, for never will you show that not-being is ~parmenides
environmental changes. choice in mateing. choice in habits. mutations. disease/microbes (or whatever i mean by that lol i think you know.)
all living things are subject to these things, and over time all things adapt and change by these things.
You shouldn't make absolute statements like this. When you say that it is all living thing, then you only need one example of a living thing that is not subject to those things to refutue your statement. You should say most, and then not base your arguments on absolutes.
Plants can have no choice in their mate nor their habitat and so can some animals like sponges or coral.
would it be wrong then to say that since stars change in timely manners based on environmental changes, that it could be considered evolution?
In the vaguest sense, evolution is just change over time. Seeing as it is pointless to have a whole thread devoted to that, it seems that Phat is talking about defining biological evolution.