Should Christians who believe in "young earth creation" be threatened by the notion of ancient civilizations that predate all major world religions?

Only if their own worldview is so narrowly restricted with a literalist reading of the Bible.

In the second half of my conversation with Andrew Gurevich of Portland, OR, we somehow tie together: apophatic theology, neurology, politics on the right and left, and paleolithic cave art.

How is this possible? I'm not entirely sure myself, but somehow Andrew is able to tie all those seemingly diverse threads together and make it work.