theory of eevolution: living things evolve through natural selection
natural selection in a nutshell (sorry, i havent really studied this, but read a bit about it, might make a few mistakes, or be very vague):
lets say there's a type of fish without eyes
that type of fish has a predator, *bigger fish*
one day, through tiny genetic mutations caused by reproduction (it always happen, tiny little bit, but always happen), a slightly mutant blind fish is born with cells capable of sensing light
that mutant fish has a better chance of surviving, as it can detect the predator, hence its offsprings are more likely to survive, etc etc, eventually, the mutant fish's population will increase, the original fish will die out/bred out, and there, evolution happened, mutant fish somewhat have eyes now!
in other words, nature select the fittest.
applying that to our current argument, the reason why we're so complicated, with all the intricate mechanism, is through tiny iteration of tiny mutations from the first single-cell organism. we're only one in a <insert very large number> of possibilities, but the reason why we have survived instead of all the others is because we are the *fittest*, the best product, and naturally we were *selected* to be THE race...
=D i feel special