The intricate balance of neurotransmitters in a brain proves evolution wrong.

A myriad of neurotransmitters and brain chemicals is needed for a properly functional brain.
But not only this, these chemicals have to exist in a perfectly fine-tuned balance.
If this balance is off just by a tiny bit, the results are catastrophic. Horrendous mental diseases develop in such a scenario.

Now evolution teaches that everything came into existence due to random mutations, trial and error and the survival of the fittest and this combined with time, lots of time, millions of years.

So then, if we follow this evolutionary logic, it would mean that generation upon generation of mentally sick "zombie animals" would have roamed the surface of the earth until finally the intricate balance of neurotransmitters had been established.
Of course we know that such a scenario would be impossible.
If generation upon generation of mentally retarded animals, generations of animals with the most horrific mental diseases one can imagine were really born, we know that such beings would just die out.
And since such a chemical imbalance would affect all animals with a brain, we would see a massive die off.
And the fossil record would show us grossly deformed animals with myriads of mental diseases.
But if evolution could not achieve this - for the survival absolutely necessary - balance of neurotransmitters, what could?