I don't know if we evolved to eat quickly, but we certainly evolved to eat as much as we could find. I'm a very slow eater, but I still knowingly eat past the point of satiety quite often. Right now for instance I'm stuffed and considering that apple pie in the fridge.... :o

One thing I will say for being a slow eater--I'm VERY attuned to my satiety. I know exactly when I've had enough. However, knowing is only half the battle. Like I said, I knowingly and willingly continue to eat even when I'm full. That's biology. The fact of the matter is, our bodies don't know that this isn't our last meal for a very long time.

Wait, I've got it! Our bodies are built to endure famine, and that's what our trouble is. So let's create a famine! :p lololol.