I agree with dave... I think that since our astral bodies are a raw energy form, it can take the shape of whatever works for us at any given time; whatever feels symbolically comfortable to us.
Ryan wrote:
"I was reading John Edward's new book called One Last Time. In it, he said that the closest encounters we have with the Other Side are dreams, because it's in this unconscious state that our own spirit, or astral, bodies, are able to travel to the other realm and meet with spirits."
I believe that we do travel around quite a bit in dreams astrally... I can usually tell if I've been wandering around in the astral planes during sleep because I will hear this unmistakable "snap"/"pop" right as I'm waking up. It's pretty loud so there's definitely no mistaking it. I also get the feeling that this "snap"/"pop" is actually my astral counter part reintegrating into the physical body upon physically awakening from sleep, but I'm still not quite sure. I do know however, that after hearing this "snap"/"pop" I usually feel a lot more tired upon waking up than I do when I don't hear the sound. It's very curious.
Ryan wrote:
"But I wonder about the nature of the spirit, astral body, or dream body. Is it eternal? Did God give it to us? Did it evolve with evolution? Does only creatures in Nature that can dream have astral bodies, etc., etc."
In my own opinion, I do think that the astral body is eternal, and constantly evolving... Since God's PUL is eternal/infinite, and our ultimate goal is to spiritually evolve into/within this eternal/infinite PUL, I feel that our astral body's/soul's spiritual evolution must therefore also be eternal/infinite. I believe that consciousness/curiosity probably starts at a very basic/fundamental level and evolves from there. Self discovery is endless. As well it should be; has to be. As Albert Einstein said: "Energy cannot be created nor destroyed... it can only be changed/transformed." We are transforming within energy/God... and with energy/God. All that physical matter actually is is energy vibrating at a "very" slow clip; thereby creating an illusory solid form. Hence, raising the body's energy vibrational level and slipping into the spiritual raw/(un/organized) energy form. Since everything in creation is made up of varying vibrational rates of energy/God... everything is God; every rock, every tree, every animal, every molecule, is God. Maybe with regards to your question concerning, "Do only creatures in nature that can dream have astral bodies, etc., etc."... Maybe "everything" in creation has some form of astral counterpart... In fact I've heard that everything that you see, touch, feel around you in our physical plane (Earth) has a spiritual/astral/ethereal counterpart from which it was derived. Almost like we are living the negative of a picture, that is Earth. "Heaven" being the actual picture, Earth being the negative. So, if everything "Here" was made "There" first, everything must therefore have an astral counterpart/body. We are all "astral transposed onto physical". We are not human beings having a spiritual experience, we are spiritual beings having a human experience. (As far as say a "rock's" astral counterpart is concerned... I'm not quite sure the details on how it evolves per say, but there is some "basic" fundamental spiritual principle governing it and everything else "seemingly" unconscious residing within our physical/all physical reality/s.) That's probably why Buddhist followers are so "delicate" with everything in nature. However, you won't find me mourning anytime soon if I step on a rock... Aside from its aesthetic appeal... the notion of "walk rocking" seems to be one of the rock's primary functions/evolutionary purposes at this point in its evolutionary cycle (whatever that may consist of)!

Maybe this makes sense, maybe it doesn't... But it's what I've pulled from what I've learned/read/experienced so far.
PUL,
Cosmic_Ambitions