Final answer:
The evolution of useful things contrasts with the unit theme of setting goals. Evolution is not goal-directed, as it focuses on adaptation through natural selection, while setting goals involves having specific objectives.
Step-by-step explanation:
The central idea of the evolution of useful things contrasts with the unit theme of setting goals. The evolution of useful things is based on the concept of adaptation through natural selection, where organisms change over time to maximize their reproductive success in a specific environment. This process is not goal-directed and does not seek to make species better in any absolute sense. On the other hand, setting goals involves having a specific objective or outcome in mind and working towards achieving it.