I think that science has yet to explain what makes us different from the other animals on this planet. To our knowledge we are the only self aware species. We are certainly the only ones that do what we do (science, religion, cities etc...) Now, I will not say that the difference is the soul. But I will say that its a possibility. Now, before you theists start jumping for joy and yelling you got one, you haven't. Its a poorly understood concept, and the possibility of a soul does not equate to a deity living in the sky judging our actions. If, and that's a mighty big IF, there is something other than a chemical mixture powering the old batteries, we haven't found it, or even seen evidence. I will say there is a reasonable doubt on the existence of a soul, and not enough evidence to convict...yet.