Do you believe in Evolution?

[Link]

I want to see what people think. Me? Personally, I don't.

[Blademaster]

Oh, goody, another debate for every extremist at TPM to jump on! I'll get the popcorn...

And just for the record, I do believe in evolution.

[.hacker]

I personally do not believe in Evolution.

[Arnen]

I believe in evolution and I don't want to say anything else because I don't want to offend any religious freaks like I did last time I talked about something like this =D

[DarkTemplarZero]

There's not much to believe really, all evidence points to evolution. That's why it's a theory: all evidence we currently have supports it. You don't see any idiotic religious fanatic attacking the Theory of Relativity and claiming that gravity is caused by the weight of God's mercy and time dilation exists because God can't keep up with you when you're moving really really fast, or Kinetic Gas Theory by saying that all gases result from God's holy fart. Intelligent design's just another religious belief that's in line to get shot down by reason: 500 years ago people believed the Earth was only 4000 years old, in 1600 people believed the sun revolved around the Earth, in 1900 Lord Kelvin believed that there was nothing left to discover in the field of physics, and today some quaintly backward people believe that God created mankind in his image even if all evidence points to the contrary.

[Link]

If all evidence points to evolution, then it isn't science.

[Jeff]

I'd just like to remind everyone that the Theory of Evolution is just that, a theory, not proven, just believed. Yes, Relativity is also a theory, but at the same time it's due to be replaced by either String Theory or something else of that nature. Science is always evolving, every theory has flaws, and there are always new theories to overcome those flaws. There might be some theory that everyone believes, but there's always room for other theories in science. From my point of view, Evolution and Intelligent Design, are just two ways of explaining the same thing, just like String Theory and competing theories are trying to explain the Universe.

[Negrek]

I do believe in evolution myself; to me, it seems very logical and covers the bases nicely.

If all evidence points to evolution, then it isn't science.

...what? I'm sorry, I don't understand what you're trying to say.

From my point of view, Evolution and Intelligent Design, are just two ways of explaining the same thing, just like String Theory and competing theories are trying to explain the Universe.

That's true in a sense, but I wouldn't compare Intelligent Design to, say, an alternate String Theory or something, because it has no scientific basis. You're correct in saying that scientific theories are not perfect and are constantly being revised--heck, Darwin didn't even know anything about inheritance when he first proposed evolution. However, I think that the core concept of evolution, the whole survival of the fittest thing, is unlikely to change as time goes on. You never know, though.

[Heald]

Evolution is probably real, so that's why I believe in it.

Think about it - unless you're an idiot and actually believe the fairy tale that is Genesis (or any other 'creation story' where humans were created in their current form), when life first began to roam the Earth, the world was very much uncivilised - while it is somewhat plausible to believe that mankind began existence 'as is' i.e. how we are now, it is not plausible to believe that the technology that we rely on to survive, such as vaccines, weaponry and heating, existed with us. Look at humanity in its current form - we're weak, cowardly, selfish beings with nought but pink hairless monkey suits and a very vulnerable immune system. Back when the world was uncivilised and roaming with large, hairy, feral beasts with big teeth and disease was far more widespread, humanity as it exists today simply would have not survived.

This isn't evidence for evolution itself per se, but since carbon dating for the planet itself goes millions of years back, whereas human civilisation can barely be backdated 10 000 years, it would be foolish to deny that this is the truth.

Also, evolution does not contradict the existence of God - it merely contradicts Genesis. Both Genesis and Evolution were devised by a man, or men, so saying that one carries weight over the other due to its author is outrageous.

[Everoy]

Let me start out by saying this: I think that science is how things work and religion is why.

I personally believe that evolution is real. And, I also believe that it was triggered by a divine being. I am not religious in any sense of the word; I have no religious affiliation and the last time I went to any sort of church I was three. There is evidence for evolution; there is no evidence disputing it.

[DarkTemplarZero]

"If all evidence points to evolution, then it isn't science."
Care to explain that statement? I didn't really understand it.

"I'd just like to remind everyone that the Theory of Evolution is just that, a theory, not proven, just believed. Yes, Relativity is also a theory, but at the same time it's due to be replaced by either String Theory or something else of that nature. Science is always evolving, every theory has flaws, and there are always new theories to overcome those flaws. There might be some theory that everyone believes, but there's always room for other theories in science. From my point of view, Evolution and Intelligent Design, are just two ways of explaining the same thing, just like String Theory and competing theories are trying to explain the Universe."
First of all, String Theory has little or nothing to do with Einstein's Theory of Relativity: General Relativity's purpose is to accurately predict the effects of gravity, String Theory attempts to explain what gravity actually is. And don't get me started on the phantom science of String Theory, while it is mathematically beautiful in the 40 or so years it has been around there has been not a single experiment to show whether or not it actually applies to our universe, and so it can't really be called a theory. Stuff like Loop Quantum Gravity seems to be the more likely explanation of what gravity actually is anyway.

And the fact remains that while evolution is a theory, all evidence says that it is true, there are countless observations of evolution (not in action, but through fossil records and such), while all theologists have to say is that randomness cannot yield such an ordered result, which is laughably false as anybody who does computer science and studies simulated annealing (wiki it. Awesome stuff) can tell you.

"A theory is a logically self-consistent model or framework for describing the behavior of a related set of natural or social phenomena. It originates from and/or is supported by experimental evidence (see scientific method). In this sense, a theory is a systematic and formalized expression of all previous observations that is predictive, logical and testable." -- Wikipedia

[Poryhedron]

Let me start out by saying this: I think that science is how things work and religion is why.

I personally believe that evolution is real. And, I also believe that it was triggered by a divine being.

I forget the exact details now, but I once read something that explained, with surprisingly convincing detail, that if God created all of the different species on Earth by deliberately manipulating DNA he could do so without contradicting a single word of Genesis, except for the part about it all taking only six days.

Evolution exists. This can no longer be denied by people who bother to educate themselves; it is too easily observable in micro-organisms as they evolve a resistance to our antibiotics. Dandelions have evolved a defense against lawn mowers by gradually becoming shorter, to the point where the whirling blades pass over them. These days, people supporting intelligent design can no longer claim evolution is a myth; instead, they have to try to explain how it can be present in microbes and dandelions and yet not be capable of turning amoebae into humans over the course of millions of years.

Oh, and by the way...one of the bulwarks of intelligent design is the enormous complexity of the human eye. Scientists have now demonstrated how such a deeply intricate system can, in fact, be produced by evolution starting with a patch of light-sensitive cells.

[darktyranitar]

I believe in evolution.

But I disagree with the whole human-evolve-from-ape evolution theory.

[Poryhedron]

I believe in evolution.

But I disagree with the whole human-evolve-from-ape evolution theory.

Humans didn't really evolve from apes...at least, not modern apes. Humans and apes just have a common ancestor.

In fact... it's been determined that humans are more closely related to chimpanzees than we are to apes.

[darktyranitar]

In fact... it's been determined that humans are more closely related to chimpanzees than we are to apes.

I'm still not buying that.

[DarkTemplarZero]

Mmmm hmmm, so where did human beings come from then, if not a common ancestor who diverged into chimps and humans, who's DNA's are over 98% identical?

[Roy Karrde]

I believe that we have more important things in this world than to worry about a answer to a question that will never be answered, and if it is, it will not be in our life time. Some people are so up tight to use any excuse to attack religion and further their own bigotry. Other people are so defensive about their religion that they cannot get their head out of the sand and look around.

Both need to look around and focus on some of the bigger things than worry about if we evolved from Chimps or if God breathed life into us.

In the end there are too many questions, and there are holes both sides can poke into each other's theories. But I would rather have people focus on the middle east nuts who use their backwards religion to kill people. And worry about the smaller questions later.

[DarkTemplarZero]

Whether or not evolution is the truth already has been answered: given all the evidence we have, the answer is a resounding yes. Science has always been like a Sherlock Holmes novel: once you eliminate the impossible, whatever remains, no matter how unlikely, must be the truth. All evidence we have points to evolution and nothing except a few quixotic skeptics to the contrary. Evolution may have a few holes, like lacking a precise mathematical model, etc. but there is no positive evidence for anything else.

To Roy: But I would rather have people focus on the [American government] nuts who use their backwards religion to kill people.
Don't diss Islam, it's basically the same religion as Christianity and Judaism, give or take a name or two. Quite frankly, all monotheistic religions are the same, give or take some names and places.
Second of all, the mysteries of life, reality, and the universe are no small question:
"The important thing is not to stop questioning. Curiosity has its own reason for existing. One cannot help but be in awe when one contemplates the mysteries of eternity, of life, of the marvelous structure of reality. It is enough if one tries to comprehend only a little of this mystery every day." -- Einstein

[mr_pikachu]

It should be fun to see the responses to this post. Or irritating. We'll see.

Personally, I think that both theories are correct, in a sense. I'm inclined to believe that a solution exists which satisfies the biblical explanation (even if it happens to be metaphorical, which it may be) and scientific evidence. But that's just my personal view, and I'm hardly about to criticize someone for having a different take on things.

I would like to mention something about the nature of science itself, though. Science works with theories, which are often based on earlier theories. But theories are naturally flawed. The first seven meaning for "theory" on dictionary.com are as follows:

1. a coherent group of general propositions used as principles of explanation for a class of phenomena: Einstein's theory of relativity.
2. a proposed explanation whose status is still conjectural, in contrast to well-established propositions that are regarded as reporting matters of actual fact.
3. Mathematics. a body of principles, theorems, or the like, belonging to one subject: number theory.
4. the branch of a science or art that deals with its principles or methods, as distinguished from its practice: music theory.
5. a particular conception or view of something to be done or of the method of doing it; a system of rules or principles.
6. contemplation or speculation.
7. guess or conjecture.

Theories are an explanation for what we have observed. Therefore, they are limited by two factors. First, the scope of our logical reasoning restricts the explanations that we can think of when we create a theory. Second, the events that we have observed are all that we are trying to explain.

When our logical capabilities expand, more possibilities come to light. When we observe further events that contradict previous theories, we must adapt and change our previous arguments to suit the new evidence.

Therefore, theories must naturally undergo constant scrutiny in light of continuing advances in logic and in evidence. We cannot assume that something is true just because "science says it is." Theories are theories, and nothing more.


EDIT: Bolded the definitions that actually apply to what I was saying.

EDIT2: Deleted a few of the bold tags upon further consideration.

[Little_Pikachu]

I believe in evolution a whole lot more than I believe that one day god just decided to make everything in the perfectly formed way it is today. Where did all these bones of ancient humans come from? Or were they just made along side the perfected humans and made to fight to the death for God's amusement?

[DarkTemplarZero]

Mr Pikachu: A scientific theory is different from the conventional meaning of "theory" in that it can't be a guess or speculation. Conjecture, yes, from the evidence given. While I don't disagree with you that theories aren't always correct, just look at Caloric Theory, but they must be proven or disproven scientifically through observation and reasoning, not through skepticism by religious nutcases who have no evidence to back up what they're saying.

LP: Such is the plight of philosophy; lots of argument that gets nowhere. For example, I could argue that the universe was created exactly one second ago by an all powerful being named Tony Montana and made the illusion that the universe was 13.7 billion years old, and, by Schrodinger's Uncertainty Principle, I can't prove it and you can't disprove it because we can't observe anything to support either argument.

[mr_pikachu]

Well, I admit that the latter two definitions I gave are a bit too extreme from a scientific standpoint. I'll go back and edit the bold tags out of that part, because you do make a valid point there.

Nonetheless, theories still have the two limitations that I mentioned previously: logical prowess and available evidence. When new ideas are considered, or when contradictory evidence comes to light, theories are changed. It's the nature of science that nothing can truly be "proven," but that we can only conclude the best explanation for the limited things we have seen. One look at how many theories there have been about the structure of atoms demonstrates that.

[DarkTemplarZero]

Don't invoke Gödel's Incompleteness Theorem here, it's irrelevant. What keeps evolution from being a scientific law (it's universally accepted among biologists, just like Newton's Laws of Motion are universally accepted among physicists for example) is three things: religious extremists, the fact that we haven't been able to observe it anywhere else in the universe because we haven't discovered life anywhere else in the universe (scientific laws must hold everywhere), and the fact that it lacks a nice mathematical model like F=ma or F=G*M1*M2/R^2.

Gödel's Incompleteness Theorem? Hah nice point. Unfortunately, most scientists and mathematicians don't want to waste their lives trying to prove axioms. We can sit here and battle on and on about whether 0=0 is true or whether Newton's Third Law of Motion is true or whether every living creature is descended from a common ancestor and not get anywhere and science would become philosophy, but thankfully the question is irrelevant. The question is what can you derive from the axiom, not how you can prove it is true.

And you cannot compare evolution to the models of the atom: none of the theories of the atom were actually scientific theories, they were "models". Even when they were published the discoverers stated that their models had some flaws and failed to explain certain phenomena. Hell, Bohr's original paper stated that, while his model predicted the behavior of the hydrogen atom to the T, it was useless for helium and larger atoms because of electron repulsion, nobody has yet claimed to have an all-encompassing theory of how an atom works. There has never been a shred of scientific evidence that contradicts evolution. Once again, we can sit here and argue Gödel's Incompleteness Theorem and whether F really equals ma, but that is irrelevant and there has never been any evidence that says otherwise, so for our purposes it's an axiom.

[youdontknowme]

I don't believe in macro-evolution, but I do believe in micro (ie. adaptation)
Nobody can prove or disprove evolution, like the existence of God; it's taken by faith.

[Negrek]

I don't believe in macro-evolution, but I do believe in micro (ie. adaptation)
Nobody can prove or disprove evolution, like the existence of God; it's taken by faith.

Yes you can. How else did some microbes become resistant to antibiotics? There was that whole thing with the moths and the sooty trees and them changing colors to remain camouflaged. And, in controlled laboratory settings, you can generate evolution though selective breeding of fast-reproducing organisms, such as bacteria or flies. Stuff evolves.

I've heard people say how they believe in micro-evolution but not macro-evolution before, but I've never understood what they consider to be the difference or what the argument is there. Care to enlighten me?

Indeed, science is a faith like religion, but one of a different nature--you can go on believing that the earth is flat all you like, but we have very conclusive evidence to prove otherwise. The existence of a God(s), by the very nature of the proposal, cannot be proven, and therefore requires a different kind of faith entirely.

[mr_pikachu]

1. If I'm not mistaken, micro-evolution is the adaptation of certain animals to various situations - you could compare it to Pokemon evolution, really. Macro-evolution is the gradual change of a species over an exceedingly long period of time into a different species.

2. "The earth is not flat" is generally taken as a scientific axiom now because it is readily observable. This is different from a theory. Human evolution is more difficult than an axiom, as we cannot go a few dozens years back in time to observe the changes.

[youdontknowme]

Yes you can. How else did some microbes become resistant to antibiotics? There was that whole thing with the moths and the sooty trees and them changing colors to remain camouflaged. And, in controlled laboratory settings, you can generate evolution though selective breeding of fast-reproducing organisms, such as bacteria or flies. Stuff evolves.

Like I said, I believe in micro, not macro.
I think some people are getting confused with what I'm saying...
When I said macro, I meant primates to humans. Micro being adaptations ie. what Negrek said about the moths.

When I said that evolution cannot be proven or disproved, I was referring to macro (at least, in my terms). Again, there's no undeniable evidence that proves the existence of such evolution.
If some day evolution can be proven like simple arithmetic (2+2=4), then I'll be damned.

[DarkTemplarZero]

So you say you believe that you believe in minor changes but not major ones? Don't you think that small adaptations bit by bit over millions of years can result in a radically different species? Think about what you're saying for a bit. Primates that were able to see over the tall grass in Africa prospered because they could find food more easily, so primates that could stand on their hind legs more readily were more likely to survive, so after some time a group of primates only stood on their hind legs, etc.


^ Evolution.


Baleen Whale skeleton. Notice it has hind legs (marked by C) ? Vestigial remnants of its terrestrial ancestors.

2+2=4 is not an axiom, it is derived from the assumption that a=a for all values of a, which you can debate philosophically but it's absurd. Evolution is more axiomatic than anything, it's just what's always been observed and there is no conceivable scientifically provable alternate theory, therefore, by Sherlock Holmes' principle, it must be the truth. Since you seem to be so against evolution, youdontknowme, tell me what you think? What logical and scientifically provable alternate theory to evolution do you have?

[Blademaster]

What logical and scientifically provable alternate theory to evolution do you have?

Magic.

What? Not logical enough?

(casts a spell that makes everyone believe magic is logical)

See?

[Mew Master]

Eh, I'm going to throw my two cents in here because as a Scientist, I actually see change evolution in action, and I just got done taking my Zoology Final.

First off, I'm a Paleontologist, so I spend a fair ammount of time looking at different species of dinosaurs and birds looking for a connection.

Second off, and the most important. Evolution is not a belief. It is a Scientific theory that can be argued either to be incredibly false, or very accurate. Just as you can argue that science and faith bang off each other like oil and water, there are some who think the two can co-exsist. I think they can, but then again, what do I know? I'm agnostic.

Well, let's look at the main points of evolution.

1. Evolution is a change in a population over an expanse of time.

Whether you want to accpet this or not, there is evidence for changes within a population. Evolution is scrutinized because we can't see the differences within out own generation. For specific changes to be taken place we need at least three successive generations to see a change. However, we can see a few trends.

Human beings have increased in height from the late 1800's the average height increased by 4-6 inches at best. We also have begun to live longer, as a result of both medicine and our own resistances to natural viruses and ailments. However, the bad part of this is that there is also an increased rate of death by corinary and cancer-related ailments. That can be partially explained by behavior and habit, but behavior is part of the driving force behind evolution.

The other fact brought up is that viruses, bacteria, and insects are becoming resistant to everything we throw at them. This happens when an exsesive use of an anti-biotic and insecticie kills all but a few of the population. That population, that survived the original onslought, is able to reproduce with more of those who are resistant. And the cycle continues with many more resistant organisms surviving and multiplying.

This also ties into adaptive radiation, where one species eventually changes and evolves into several different species with a common ancestor. This is why Mammals, Reptiles, Birds, and Fish are tied to the first few multi-celled organisms.

2. Change is bound to happen in a population.

We may be only 99% different from the rest of the world's species however there is that 1% difference that accounts for variation.

A population is each genetically different. When they mate, the genetic variations increase drastically (X^2). Which allows for different genetic combinations. Those combinations that survive pass on those genes to the next generation and so on...

3. Organisms in a population are not the same

See previous point.

4. Variation is repeatable across Generations.

As I stated earlier, variation across time is seen through bacteria (because they can reproduce quickly and have shorter life-spans), or through statistics (human height, as mentioned earlier). And these variations continue on as the organisms live, grow, and reproduce.

5. More offspring = More survive and reproduce

Different species have different ways of surviving. Cats have litters of kittens between 3-7. Humans have young that number anywhere from 1-7, but more often it's just one. This has to do with the survivability of the species. Cats have some natural predators that threaten their young, so they have large batches to ensure that they survive. Humans on the other hand have no natural predators (other than ourselves, you can argue either way), and thus have far fewer young with a longer gestation period (two months in a cat vs 9 months in a human). Other species, however, are fully able to stand the second they're out of the womb (antelope)

I'll end with a few final notes.

When you look at the different taxinomic classifications of animals, you can see change across them that mimics change over time.

From "Protozoa" -> Porifera -> Cnideria -> Platyhelminthes -> Nematodes -> Mollusca -> Annelids -> Arthorpoda -> Echinodermata -> Chordata. The addaptive radiology branches out into the living organisms of the animal kingdom.

Now, I am a supporter of Evolution. I am also respectful of other people's beliefs and I don't try to force my ideals on someone else. Just so long as they don't force theirs on me.

Okay... there's my..... *counts fingers* Um.... 34 cents worth. ^^U

[Jay Umbreon]

im a believer =]
though it would be nice to believe that lots of virgins are waiting in heaven for me ^_^ ...but still...
nah, im with darwin.
religion gives people hope for a life after death
it gives people meaning where there's uncertainty
again, hope when there's fear
but the cold truth, is most probably evolution
born, die, that's it.

[Negrek]

(*simultaneously testing BBCode thingy*)

1. Individuals don't evolve (thus, pokémon "evolution" is technically a misuse of the term). As it was defined to me, microevolution refers to the evolution of a specific population, whereas macroevolution the species as a whole. What I'm getting at is I don't see how people can believe in one and not the other.

2. The evolution this topic is discussing is not specifically human evolution, but the process in general. And it is even moreso readily observable than the curvature than the earth, unless you have a spaceship handy or some really fine instruments--you can engineer evolution experiments and observe their results in your house if you feel so inclined.

Edit: Okay, so the center and bold tags worked, but the color tag did not...? *goes away to fiddle*

Edit-edit: It disappeared as a result of my edit. Woe!

[mr_pikachu]

I'll just comment on the micro/macro-evolution part...

Think of it this way. Micro-evolution is like a caterpillar that becomes a butterfly. Macro-evolution is like apes changing into humans over thousands of years.

[Negrek]

(plz to be limegreen text this time)

Micro-evolution is like a caterpillar that becomes a butterfly. Macro-evolution is like apes changing into humans over thousands of years.

No. Individuals cannot evolve. Metamorphosis =/= biological evolution in any way, shape, or form. The transformation of a caterpillar to a butterfly is not evolution, much less micro-evolution. Micro evolution is a change in the frequency of alleles in a population--if a population is not in Hardy-Weinberg equilibrium (a practically impossible state), then it is undergoing micro-evolution. The Wikipedia article on the matter gives a quick run-down; I'm too lazy to look for a more illustrious source.

(hahahaha, success! ... however temporary)

[mr_pikachu]

*grumbles*

It was a metaphor to explain who each term affects. It wasn't meant to be an actual example...

Oh, forget it. I should know better than to post in these topics by now.

[Blademaster]

No. Individuals cannot evolve.

Actually, I'd thank that to be false, simply because there had to be some point in time where one species became another.

For instance, say humans evolved from monkeys. Evolution is really slow, right? So gradually, the monkeys in question became more and more human, until eventually one of them 'crossed the threshhold' and became more human than chimpanzee. If individuals couldn't evolve, evolution would never happen - it's not like one day every monkey suddenly decided 'I'm gonna turn into a human today, but only if everyone else does, too.' It just seems like individual evolution must happen, at least sometime at some level, because the only other option available is group evolution, and that - that more than one of a certain species evolved into a certain other species at a certain time - seems impossible, or at the very least, infinitely less likely than the alternative.

And I base all of what I just said...

On absolutely nothing. Thank you,

P.S. Come back, Bri! This was just getting fun!

[Negrek]

It was a metaphor to explain who each term affects. It wasn't meant to be an actual example...

*blink*

But it didn't correctly explain who the term affects, which was the point of the last post. But sorry for turning you off the debate. ^^;

[Negrek]

For instance, say humans evolved from monkeys. Evolution is really slow, right? So gradually, the monkeys in question became more and more human, until eventually one of them 'crossed the threshhold' and became more human than chimpanzee. If individuals couldn't evolve, evolution would never happen - it's not like one day every monkey suddenly decided 'I'm gonna turn into a human today, but only if everyone else does, too.' It just seems like individual evolution must happen, at least sometime at some level, because the only other option available is group evolution, and that - that more than one of a certain species evolved into a certain other species at a certain time - seems impossible, or at the very least, infinitely less likely than the alternative.

Perhaps I was a little confusing--yes, individuals are different and show characteristics that deviate from all others of their species. However, they don't evolve themselves, that is, change genetically throughout their lifetime (mostly, but I'm not going to go into specifics). At some time, yes, there was one tree-dweller born that was more "human" than any of his relatives, but this was a result of the genetic lot he (or she, but I'll go with masculine pronouns because I'm lazy) had been dealt. No predecessor ever gained the "human" trait during their lifetime--they did not metamorhpose into a slightly more human being during the course of their hunting and gathering. A person's DNA is fixed at birth, and for all intents and purposes this cannot be altered by the individual afterwards, so a single creature cannot be said to evolve.

[Blademaster]

So, then, a monkey that was 49.99999999999999999999999999999999999999999999999 99999999999999999999999999999% monkey gave birth to a monkey that was 50.00000000000000000000000000000000000000000000000 00000000000000000000000000001% human?
But..... WHEN did that happen? At some point, when that child was an infant, a newborn, an embryo, a zygote, or even an egg, it had to develop that extra 0.000000000000000000000000000000000000000000000000 00000000000000000000000000002% from somewhere. So...

?

[Negrek]

There are several ways that could have happened. First, there might be a perfectly "normal" cause for it--something that happens as a result of the mechanics of sexual reproduction (omg I get to turn this into a sex thread yay). When sex cells get made, they undergo a process called meiosis. When that happens, their DNA gets replicated so it can get put into the next generation of cells. However, before the DNA gets split up and reassigned to the next generation, it may undergo a process called crossing-over, where the replicated chromosomes exchange bits and pieces of DNA, resulting in some new combinations. There's one source of a change in genetic code. After that, the DNA all gets split up into new reproductive cells--however, only half the chromosomes make it into any one new cell; for each offspring, half the DNA comes from the mother, and the other half from the father. Thus, the kid is something totally different from either of its parents--an entirely new sequence of DNA, with uniquely combined traits as a result. Possibly, this might lead to some new adaption (perhaps, say, exceptionally long legs, if both parents had long legs).

Beyond that, there's mutation in the reproductive DNA. This can happen in many ways--radiation, as I'm sure you've heard, can do that. Alternatively, there might be a mistake in copying the DNA. And sometimes worse mistakes get made during the production of reproductive cells--wrong numbers of chromosomes getting put into a cell, stuff being improperly copied, and so on and so forth.

So that's where little differences in genetic code come from: mutations or recombination of parents' DNA, if the organism reproduces sexually.