Not bad
As the previous reviewer said, the "naught" joke got old pretty quickly. Don't we have scientific notation for things like that nowadays?
The flash was pretty good and was pretty funny, even if I don't quite agree with it. Not because I don't believe in evolution, but rather because the whole concept of a "species" doesn't really make a lot of sense. Biologically speaking, there isn't a good definition for a "species" (most people assume that there is, but there's actually a big controversy about it), so your whole thing about the first 100% chicken arising from two parents who aren't quite 100% chicken is dangerously misleading.
There is no point where one species becomes another, there are just labels of convenience and various degrees of separation. And if you don't believe me, ask yourself why it is that many animals that are labelled different species can interbreed (lions and tigers for example - google "liger" and you will come up with tons of pictures). In fact, this should be obvious by the way that evolution works - new "species" aren't created overnight, old species change form slightly over millenia until they end up being different. There's no exact line where something becomes a chicken - we can always make an artificial line based on percentage of difference from today's chicken DNA, but it won't really mean anything in the natural world aside from making it easier for humans to classify things. And as far as I know, no biologists have agreed on just where that line should be. After all, how do you define what is "100% chicken" when every chicken alive is different?
Everything on Earth is related, and distinctions like "species" might be usefull for human science (if they could just pin down what the definition of a "species" should be) but are meaningless in nature. To find the ultimate answer to the question of "chicken or egg" we'd need to go back in time down the long evolutionary ladder and find where the first collection of chemicals that we call "life" appeared. But then again, "life" might be as artificial a distinction as "species" is - for example, viruses, by far the simplest "life forms" around, are just small inactive groups of chemicals that basically only come alive when they can replicate. The difference between life and non-life isn't as great as most people think, so the question of "chicken or egg" may well have no answer at all.
Anyway, I'm sorry for going on this over-long rant everyone. Watch the animation, it's nice. :)