What is the soul.. it's a hard question. I think a soul is what gives us freedom to think, the ability to choose.
I believe that plants, for example, do not have a soul, they just do what they do because it's what they must do to stay alive, they cannot choose to not absorb nutrients from the ground or to stop absorbing sunlight to process their food. For a plant to die the plant's environment must be damaged in some way, a plant cannot take it's own life or even decide for itself what it wants to do. It's path is predetermined and it has no option but to stick to it.
Animals, excluding humans, I believe have a soul because of emotion. My dogs have all had emotion; Happiness, Love, Sadness, Fear. Perhaps it cannot be seen in something as small as a mouse, but in animals which we become attached to we are able to sense the emotions of them. Animals, not humans, appear to also be stuck to a single path. All my dog does is sleep all day, maybe it'll ask me for a walk or some food later on, but, should I deny it it's food - will it try and find some? I'm not going to test it, I love my dogs too much, but it's an interesting thought, wouldn't you agree? Do my dogs, and your pets have the ability to choose?
We know humans can choose - I'm choosing to write an essay for a reply because it's an interesting topic. It may be predictable I reply to a topic such as this but it's certainly not been predetermined - I have the ability to choose whether what I'm writing now is seen by everyone who wishes to read it. But of course, my reasoning for believing in a soul doesn't just come from "I can choose".
I've had an out-of-body experience. I was 6 years old. I saw my youngest brother being born. I can still recall various pieces of information which I know I cannot have known, nor guessed, with the mind of a 6 year old. I recall the colour of his umbilical cord, I recall the colour of the sky at the time he was born, I recall the sofa he was born on and I recall the people who were in the room. Should I have been 12 years old, I would have dismissed it as coincidence as I would probably have known or been able to make an educated guess at what happened at that time. But I was six years old. A shame, because of the obvious lies which come from fanatics mouths when they say they've died on an operating table and saw a bright light, many legitimate experiences are ignored and set aside as vivid dreams. Of course it's only logical to not change your mind over something one person has experienced, especially if you only know them through an internet forum and are known to be a little aggressive in the somewhat religious topics such as this.
But death, do I think it's the end? I don't know, and I don't want to. Whether there is an 'afterlife' or not I do not wish to know before I go, thinking that I'm just going to be a corpse of rotting meat or dust inside an urn for eternity, until my essence becomes nothing but earth in the ground is a depressing thought which I would rather be at the back of my mind when the time comes. Though I personally see reincarnation to be the more probable of the 'death theories', that may be down to me not liking the idea of a complete end to my thoughts.
That gave me a laugh, but please keep on topic.