First I should note that, I have done a lot of thinking about multidimensional existence, so my argument is based heavily on the idea that there are dimensions beyond the ones we are aware of, and that they interact with us in ways that we do not yet understand. If you have trouble wrapping your mind around the idea of dimensions beyond our own, I would suggest taking a look at Edwin A Abbott's "Flatland", even if you're not interested, it is still a great read.
Second, in this argument I assume that living matter is somehow different from inanimate matter.
Third, the English language is very poorly suited to this sort of discussion, so some words are not truly accurate, but are the best approximation that I can think of.
Fourth, though I will state that this is my opinion or that it is my belief, what follows is just an idea that I have tinkered with for a while, it just comes out better if I write it as a personal profession of belief rather than a statement of theory or fact.
Okay, so, it is my opinion that everything since the initial creation of the our known universe has occurred in its own time and by its own method, that is, without the willful intervention of any higher beings. Eventually, life formed, whether here first (I find that very unlikely) or elsewhere, matter elevated itself (or was elevated), from inanimate to animate. When this happened, or perhaps because it happened, extra-dimensional consciousness was able to permeate our physical dimension and (Again, I believe that this is not a willful act but a sort of natural order. Think water bleeding through tissue rather than fingers poking through.) become linked to the newly formed organisms.
Every living being is linked to this entity (or entities, but the concept of one vs many may not apply). This is what forms the "observer" part of our own consciousness, the part that sees through our eyes, hear through our ears, and so on, but is also able to "look" back through our memories and perhaps to deal with emotions. The observer is present in all living beings, but is restricted by the tools it is given, smaller brains would mean less complexity, which would mean less capability, along with other factors like sensory organs and "output" methods (fingers capable of fine motions, vocal chords capable of a range of sounds, bio-luminescence, etc).
When an organism dies, the consciousness is forced back out, or perhaps simply recedes, leaving dead matter, the shell of the being. Since the memories and personality are stored physically, I would assume that they are lost at death, though it could be possible that something would be transferred along with the receding consciousness.
So to finally address the point, the soul of an individual is just a part of a much larger entity that exists beyond us, but forms our own consciousness and the consciousness of all other living organisms.
I will not make any attempts to say that this idea is ironclad (It is anything but), but I find it an interesting thought experiment if nothing else. I would like to say that any debate over complex ideas, is good, anything that gets your brain working in a way that it normally wouldn't. However anyone who answers immediately and without serious thought is doing themselves and all of society a great disservice, you owe it to yourself to entertain the idea, even if it's just to get the gears moving, but who knows, you may have a revelation, that gives you new insight on the world.
