It uses a stack [1]. Therefore, I like it &lt;3<p>[1] The stack is used in place of an <i>explicit</i> fitness function. I have nothing against fitness functions. But the bit about using a short stack instead, is really cool.<p>Edit: Woa. Hang on. New organisms are pushed to the <i>back</i> of the structure while dying ones are popped off the front- so that&#x27;s a queue. My bad. But I still like it.