Archaeologist Robert L. Kelly is the author of The Fifth Beginning: What Six Million Years of Human History Can Tell Us about Our Future. He looks at four world-changing inventions of humankind – technology, culture, agriculture, and the state – each of which contained the seeds of the next, and then looks at the archaeological record that our society is creating to hypothesize a fifth phase of human existence. And it’s one that might make our present time look positively prehistoric.