Quote from destroyer:
I'll tell you why you don't know how. What you're describing here is not the theory of evolution, it doesn't even remotely resemble the theory of evolution. You have to understand what the theory is really about, then you'll know. Let me try to explain it, I'll go out of my way to put it in as simple terms as possible, so even a third-grader would understand.
Let's do a simple example that you can recreate on your own computer. Say we start with a number, 198472836, and you want to turn this into 999999999. What you do is, you start by reproducing the number 198472836 with small, completely random variations, several times. Now if you state (computationally) that you want to keep all reproductions that includes more 9's than the parent number and let them reproduce once more, you'll start to see a change. After one reproduction your number might for instance be 198479896. This will now be reproduced instead of the initial number. After reproducing this one several times, one of it's successors might be 199499896. So the others gets discarded and this one is reproduced. After repeating this process several times, eventually you will end up with the number 999999999.
All you had to do is:
1. Reproduce the initial number with small random variations, and
2. Keep and reproduce only those reproductions who are best fit to serve a certain purpose (being all 9's in this instance).
So far so good, right? We know it works as these basic principles are being used extensively in a wide spectre of scientific areas for optimization purposes, and in artificial intelligence. If you still doubt it, you can write a simple program that does this process for yourself, and see that it works. Just a few lines of code.
Now let's take a look at nature. We know for a fact, that when something in nature is reproduced, small, random changes (errors) occur in the reproduced genetic material. This happens without exception. We also know that in various places in nature, various traits gives a larger chance of survival. The parallels we can draw from the numbers example to this should be quite clear: The environment in which a population lives determines what will and what will not be kept and reproduced, just as we computationally decided to keep and reproduce numbers with as many 9's as possible in the numbers example.
Let's do a nature example. Say we have a large population of bunnies that are equally mixed white-, grey- and black furred, on an isolated island. At some point in history, eagles arrive at this island and they start hunting the bunnies. They have very good contrast vision, so they can easily spot the black and white bunnies, but they're having a hard time spotting the grey ones. So after a couple of generations, the white and black bunnies are reduced in numbers, while the grey ones have hardly been affected. The grey bunnies will reproduce more than their black and white counterparts. Another generation goes by, and the black and white bunnies are reduced even further. Eventually the bunnies will be almost all grey, with a few exceptions here and there.
Again, the terms are:
1. Reproduce the initial population with small random variations, and
2. Keep and reproduce only those reproductions who are best fit to serve a certain purpose (having a color that's not easily spotted by the eagles in this example).
This happens in only a few generations. You can imagine for yourself what kind of changes can take place over thousands of generations, or even millions of generations. You see, it's not the bird that decides what it should be. It's the combination of random reproduction and selection of the fittest that decides.
So, whether you believe that God created us and all the animals 6000 years ago or not, you understand that if we stay here on earth for say another five hundred million years, evolution will take place and the animals of this future world will be fairly unrecognizable to us. Evolution is an inescapable fact.
