Even as a sociobiological just-so story, this is pretty goofy. Let's see: if people sit around waiting for something good to happen due to pure luck (say, a tasty deer wanders into camp), those people are likely to have better reproductive success than people who actively go out and hunt and gather food. Wha---? It's much more plausible to argue that natural selection favors those who develop skills and knowledge that ensure survival of self and family. Reliance on "sheer luck" is way, way down on the list of the survival strategies.
[WS:] That is not what I said. I said that expectation that the "manna will fall" can help surviving during hardship and keep people going in search of greener pastures, as opposed to succumb and despair. Foraging is a specific set of skills - very different from skills required to manage the environment to produce resources. What makes a successful land cultivators or producer makes a poor forager and vice versa. Since foraging accounts for most of modern human history on this planet, I would conjecture that it lead to some evolutionary adaptations - more likely than evolutionary adaptations as producers as sociobiologists claim. I would conjecture that emotional predispositions would be one such adaptations, on the assumption that all emotions and cognitive processes are "hard wired" i.e. produced by brain chemistry.
Wojtek