Has human nature changed over the course of history?
Human nature has not changed; the human race hasn't changed one iota in 6,000 years. People become corrupt and then more corrupt, as corruption breeds total corruption. This pattern persists across history, evident even in religious systems and their leaders.
Les explains that after seeing ancient ruins, such as the house with multiple layers of expensive wall material, he concludes the human race hasn't changed one iota in 6,000 years. People get corrupt, then more corrupt, and he notes corruption breeds total corruption. He says religion has always been that way: look at any religion, and its higher echelons live sumptuously off the income from that religion.