In your new book Origins you describe a hypothesis that I had never heard before. It causally links basically the cosmic cycles of the earth with the evolution of human intelligence. And what was driving that process over five, six million years since we diverged from the chimpanzee lineage? A staphico dried out because it was being pushed upwards. The Rift Valley in East Africa is very sensitive to balance between precipitation and evaporation. There's this whole set of lakes on the Rift Valley floor that in certain periods of time for certain periods, flicker rapidly in and out like a loose light bulb. So the idea is that it is that rapidly changing environment,. that rapidly changing climate that we