A growing belief that behind every event lay intention—be it an evil thought in the mind of another, or the benevolent whim of a god in the sky—was perhaps inevitable in creatures with an innate understanding of causality. If you were smart enough to make multicomponent tools, you eventually came to believe in gods, the end of all causal chains. There would be costs, of course. In the future, to serve their new gods and shamans, the people would have to sacrifice much: time, wealth, even the right to have children. Sometimes they would even have to lay down their lives. But the payback was that they no longer had to be afraid of dying.

Chapter 11 Mother's People section IV (pp. 370-371) - Evolution (2002)