Here is a good metaphor for a problem Mother Nature has to solve. A small child is playing on the equipment at the playground. The child knows what she is physically capable of but doesn’t know what is safe. If Nature knew about swings and see-saws and monkey bars she would just encode their riskiness into the genes of the child and let the child do the optimization.
But these things came along much too recently for Nature to know about them. Fortunately Nature knows that whatever is in the child’s world was pretty likely also in the parents’ world and by now the parents have learned what is safe. So Nature can employ the parent as her agent.
But in this family-firm, the child is a specialist too. For one thing she has up-to-the-minute information about her physical abilities which change too quickly for the parents to keep track of. But just as importantly the child is the cheapest source of information about what’s in front of her. Nature could press the parent into service again to investigate the set of possible activities available to the child, but this would be costly to the parent (for whom this carrier of only half of his genes is just one of many priorities) and so would require extra incentives and anyway that information is more directly accessible to the child.
So Nature’s organizational structure utilizes a tidy division of labor. The child’s job is to identify the feasible set and the parent’s job is to veto all the alternatives that are too dangerous. One last constraint explains the reckless kid. The child cannot communicate the feasible set to the parent. This leads to the third-best solution. The child just picks something nearby, say the rope bridge, and starts climbing on it. The parent is stationed nearby ready to intervene whenever the child’s first choice is too dangerous.
And thus the seeds of much later conflict are sown.