Do you ever LEAVE this world? When we die, what happens to our soul or consciousness? Does it just ... disappear? Maybe it's something like energy, it doesn't disappear. It's just passed on to other forms. So it is with human, when we die, there's a greater power up there or down somewhere that collects our souls and inserts it into another living being. Maybe there's a finite number of souls on earth - say 10 trillion. Earth was once roamed by 10 trillion animals. Then human comes along. It's common knowledge today that human population has been increasing centuries by centuries while great number species of animals are going into extinction. If it is ever possible to count the total number of living beings on earth, maybe we'll find that there're just 10 trillion of us - human and animal combined. Maybe that's how Reincarnation works.