I've always thought this was just a strange thing......we can end an animals suffering by having them PTS. But we cannot do this with humans, because it's considered murder. Even though a human could actually TELL us they don't want to live any longer.
When my grandpa was in the hospital during his last days he was in so much pain. I will NEVER forget the look in his eyes. He had piercing blue eyes and it felt like he was begging me to help him end the misery he was in. He had to suffer until that day he was finally at peace.

Sorry, this is a little off topic, but it's what came to mind.