In an episode of Cheers Cliff is telling his buddy Norm the Buffalo Theory, Cliff sure has a way with explaining things.
You see Norm it's like this.....a herd of buffalo can only move as fast as the slowest buffalo. When the herd is being hunted it is the slowest and the weakest that are taken from the back of the herd and killed. This natural selection is actually good for the herd as a whole because the general speed and health of the herd keeps improving with the regular killing of the weakest members.
In much the same way the human brain can only operate as fast as the slowest brain cells. Now as we know, excessive intake of alcohol kills brain cells, but naturally it attacks the slowest and weakest cells first. In this way the regular consumption of beer eliminates the weaker brain cells, making the brain a faster and more efficient machine.
That Norm is why you always feel much smarter after a few beers.