One way to imagine how other realities could exist side by side with our own is to consider the forces that produced the diversity of senses and intelligences right here on Earth. In a real way, there are already alien worlds right here among us. Every Earthly creature perceives the world in an "alien" way. Dogs. Bees. Bats. Cats. They experience the world with different kinds of senses. They can smell what we cannot, they can see what we cannot, they can hear what we cannot. If the organisms of the Earth were somehow able to describe their world to you, it would probably not be recognizable to you. It would seem like the wildest world from any science-fiction story. Moreover, if you were able to describe the world to another species, they would "see" no resemblance to their own. Our sense of reality would be different; our way of thinking would be different, and even the practical technology we would produce would be different. We do not have to contemplate aliens or science fiction to imagine alienlike senses and bodies. The animal world of Earth is so diverse and full of different senses, that creatures are already walking among us possessing "alien" awarenesses beyond our understanding.