Scientists taught rats to drive rat-sized vehicles in exchange for treats. When then offered treats without needing to drive, three quarters of the rats preferred to operate the vehicle to get the treats.

Many of the trained rats were observed taking an unusual pose while watching the scientists set up their vehicles. The scientists had only seen the same pose before in rats that were high on opiates.

I think the most obvious conclusion to draw is that rats enjoy learning and using new skills when there’s a reward involved, and that often the skill itself is the reward.