The game of life is where the world (a 2D grid) contains entities that breed and die. If an entity is all by itself, it will die off (no one to mate with). If it is around too many other entities in a particular area, it will also die off (not enough food). If conditions are right though, the entity will reproduce and live on. This is a simple program with simple entities that can only sense the environment directly around them and live or die according to the rules of the world. The simplicity of this leads to a very predictable set of events, but is very efficient in the sense that there is very little computing power used to determine what entities will grow and breed and what entities will die out. When there are lots of entities that are placed correctly, they can sometimes appear to be intelligent. Some people have even placed the entities in specific locations so that they can emulate different low-level hardware which then can be put together to simulate a computer. Getting back on subject, sensory systems usually display traits that are similar to the ones in the game of life.