[quote=xAsunaWolfx]
@Brand- Agreed. Asking why there is still dirt doesn't make sense since the earth is really composed of it and without dirt... Well, there would be little to no life. While monkeys are.... Monkeys
[/quote]

tl;dr: Maths and statistics.

We'll over-simplify it to an extreme.

You have 100 subjects. Lets call them Original Monkeys. Original monkeys have a breeding rate of three per year, as the base value to follow.

Now, random mutations occur within the Original Monkey breed, as when two parents mate (or in the case of cells: asexual reproduction) there is a chance that small parts of the genetic code get written incorrectly. Like if you keep making a copy of a copy of a copy of a copy--eventually, somewhere down the line, one copy is going to be different to the original due to an error in re-sequencing the code from its base parts.

So! We have a few mutations begin to appear. Some of them are beneficial, some are not, and some of the Original Monkeys do not mutate--after all, some copies do end up perfect by random chance.

Now lets say after a few generations, there are two new subtypes of Original Monkey: Fast Monkey and Rabbit Monkey. Fast Monkey is faster, and thus escapes more predators. Despite breeding at the same rate, more of their children survive, and thus start to dominate the habitat that the Original Monkey used to be the most effective in. Rabbit Monkey uses a different advantage: Multiplying faster and more often. Rabbit Monkey has six children instead of just three, so even if Rabbit Monkey loses two children to every one child Original Monkey loses, Rabbit Monkey still multiplies much faster and thus dominates the environment better, thus spreading that gene more effectively than the Original Monkey does.

Original Monkey then either continues on, or gets outpaced by evolved predators/its descendents.

Several generations later, and with further mutations, and you'll have several new subtypes of monkeys based on Rabbit Monkey and Fast Monkey. Continue going on and on and on, and eventually, a fast monkey sub-type might breed wings, or a rabbit monkey subtype might learn to burrow and evolve the appropriate tools for it. This doesn't remove the old versions from the environment, this simply means that the reproduction process is imperfect, occasionally glitches, and creates new traits, some of which are beneficial and thus naturally allow more survivors to pass it on, and some of which are not, which damage survival chances and the odds of passing it on.

This is also why you see imperfect design flaws--some imperfect things still get through by random chance. For example: The human appendix. It's totally worthless now but if it ruptures [i]it will probably kill you if you don't get immediate medical attention[/i]. Why is it still there? Because one of our ancestors needed it for some purpose that we no longer use it for as a descendent.

[url=http://www.livescience.com/21513-vestigial-organs.html]Here, an example of five human body parts that are totally worthless nowadays[/url].

And that's the tl;dr to evolution as a process. Out of 100 original monkeys, 10 have random small mutations, 5 of them reproduce more successfully due to that mutation, which then spreads through as a dominant gene. There are still original monkeys, they just aren't as effective anymore. Like how each edition of Windows is supposed to improve upon the previous version--some of them are terrible and die quickly, like Vista or ME, while others are great and live on for ages, like XP. XP spawned Vista, but Vista was inferior, so XP outlived it. Vista spawned Windows 7, which was better than XP, but hasn't totally eliminated it, and so on.

Hope that makes sense.

[quote=Shy]
Wow this thread exploded 0.0
[/quote]

And remarkable, it isn't closed! Life's little marvels, eh'?