The Great Leap Forward is probably one of the most hotly contested aspects of evolutionary genetics. It’s a mystery really. We know that around 50-60,000 years ago, there was a sort of ‘Big Bang’ in human intelligence.
-- Kate (Chapter 22 paragraph 9)

Importance: The reader is introduced to one of the theories as to how the homosapians became suddenly more intelligent than the Neanderthals or Hobbits. This is the first indication that something other than evolution may have been responsible.

About 70,000 years ago, a super-volcano erupted at Mount Toba, here in Indonesia. The eruption and ash as well as the resulting climate change, reduced the total human population drastically, maybe to as low as 10,000 or even less.
-- Kate (Chapter 22 paragraph 1)

Importance: This is an indication of how the humans were able to survive against all odds. They were the ones in the middle of such a destructive event, while the Neanderthals and Hobbits were far enough away to remain...