Because of the many countries that make her up. When you look at a map of Europe you'll see the borders are very zig-zag and fit together just like a jigsaw puzzle would. I hope that is what you were asking about.
Or maybe he has cut up a world map and got tired after cutting up Europe and now it looks like a puzzle because he is trying to put it together
Europe was form around many smaller states and a "few" wars here and there. That could be one explanation for why our borders has so many curves
Not to mention geological features, such as mountain ranges and rivers that denote boundaries, of course.
A bunch of selfish men took a beautiful picture and tore it into a 1000 pieces? Just kidding... I don't know.
