I wonder about day-to-day Rome or ancient Egypt. Some documentation exists, but most tell about the life of the nobility. I wonder what life was like in advanced civilizations in which there were no great changes in status, style and technology for centuries at a time. It's impossible to imagine such a world from our modern perspective. On the other hand, I suspect that basic human nature hasn't changed - the family dynamic almost certainly existed in recognizable form five and ten thousand years ago.
That's really the underlying beauty of creating documentaries that explore some aspect of the human condition - there's common ground to be found with almost anyone - the fun is finding where the common ground lies.