Section 2 of Chapter 1: The cruelty of chance:

We have to realise and accept that chance play a big role in life.
Nature does neither have preferences nor empathy. Nature just applies the rules in a way that we human could call cruelty.
It is not difficult to imagine the situation of the former hominids and think how often a bit of luck was necessary in many situations.
But luck is a random phenomena.
There is no fixed rule about who will be lucky and who will not.
It is not difficult to imagine that people started to think that some rituals would help to bring luck to them.