Are lost ancient civilizations real?

Most archaeology textbooks tell a fairly similar tale of human civilization: from stone tools to precision technology; from petroglyphs to written language and art; from nomadic life to city-states. But a growing group of researchers and academics say we might be missing something. Have we overlooked signs of earlier advanced cultures? 

This episode digs into alternative theories of human history and whether or not there is credible evidence to support them. Might there be an era of ingenuity lost to time? Or are we simply inventing a more epic past because it makes the human story feel bigger?