Evolution by natural selection is an incredibly simple process, basically what survives breeds, what doesn't doesn't.<quoted text>The Evidence surrounds you ! Darwin's theory of Evolution is a prime example ! According to the theory, Life evolves to adapt to the changes in its environment so it can survive ! That sounds like a Supreme Designer to me, to imbed into the genetic code of all living creatures a fail safe system for survival, that is NO Accident that was planned !!!!! Darwin was even more astounded and confused by Human Beings, Because we have evolved well past our basic needs of survival ! Our minds are such that we can embrace the Universe ! We are going way past survival into another realm that has nothing to do with survival or Evolution ! WHY ?
So it's the trials of life that eliminates the least well adapted leaving the better adapted. No designer is required for something so simple.
Despite our large brain, a hundred thousand years ago there were very few people alive. It's only because someone invented farming that the human population has exploded. As we lack the teeth and claws to fight of predators our ancestors needed to make their own weapons and that requires hands and the brains to use them. So yes we did need to evolve a big brain.