If zombies are brain eaters... how do they populate?

[flesheatingzombie]

This has always been a question on my mind, about the idea that zombies eat brains. If a zombie ate your brain, you would not become a zombie... the brain would have been punctured and thus the zombie could not form. Where does the idea of zombies being only "brain eaters' come from and how did they explain how new zombies were formed?

My guess is just the movies, but still when something needs to be shot in the brain to be killed, and a bite infects and creates more... in no way should it eat the brains of its victims.

[OVERKILL]

 The whole zombies as brain eateres came from RETURN OF THE LIVING DEAD, which was a great movie, but just that, a movie. In that movie zombies didn't need brains to function, even dismembered body parts would continue to attack. They ate brains because it killed the pain of being dead, one zombie stated she could feel herself rot. Yes zombies could talk in this movie, which gave rise to the biggest zombie catchphrase - BBRRRAAAAIIINNNNS!
 Of course other catchprases such as "send more cops" and "send more paramedics" were some of my favorites. There was no way to kill these zombies, headshots didn't work. In lateer, less good, ROTLD films it was discovered that electricity would deanimate them. In the last 2, gunshots to the torso and even kung-fu were effective methods, while some were still indestructable in the same movie, but don't get me started on those last 2.
 If you have not saw the first movie, if worth checking out. If you like it ther are 4 more sequels, but none as good as the original in my opinion.

[flesheatingzombie]

I'll give them a look, it's good to see some history of zombies.

[OVERKILL]

 Gotta know your enemy.

 I actually had a HUGE reply, but edited it for length and I didn't want to give the whole movie away either.