Seems hard to believe. But an experiment suggests it. The article is Chimps choose more rationally than humans. My student BRUNO MEJIA sent me this.
It reminds me of research that was done at Texas A & M some years ago. They found that rats and pigeons act rationally. If they had to press a lever so many times to get a drop something to drink or a pellet of food, they "bought" less of either one if the scientists raised the number lever pushes it took to get one. This was like raising the price. More lever pushes to get either food or drink, the less they tried to get of it. So they followed the law of demand. This was reported in Steven Landsburg's book The Armchair Economist.