I personally believe the soul does not die. So it's not so much an after life as a continuation of the soul. Yes the body or shell does and turns to dust or ashes in some cases. Be creamated. I think of life here on Earth as an educational training. Where we learn and grow.
I have a good friend who has a pigs heart. He seems to have no problems. The only way to tell is from the scar from the surgery. His blood pressure runs a little higher then normal. Never caused a problem that I could see.
RE: Why war exists
It's all about power and money.