I do not understand the concept of the soul. I would imagine that the so called soul would be the part that goes wichever direction to heaven.
In my already limited view of the soul I can certainly not understand why only humans would get one. I would think that the soul is used to explain free will to humans and life. The free will we hold has to be in animals as well as they are so similar to us. And life certainly does. So I can only asume that the so called soul is also present in animals.
If all life on earth has souls, and aliens look as if they are alive, I think they too would have a soul. And ofcourse that soul needs to go somewhere after we really didn't die..
On the other hand, we should be able to read it in God's book. I asume those aliens received one as well. All we need to do is figure out wich of their books is the true one.. Easy task...