Found this some time ago, I can’t remember who first told me about it. I don’t buy into everything he has to say but an interesting read none the less. I have no connection with the author or the site it’s posted on, just thought I would pass along the information.
http://thesurvivalmom.com/wp-content/uploads/2015/03/Beyond-Collapse.pdf
http://thesurvivalmom.com/wp-content/uploads/2015/03/Beyond-Collapse.pdf