Puzzle Solvers

There is an old fable about a thirsty crow that drops pebbles into a jug to raise the water so it can drink.

Scientists have tested this for real.

In experiments, crows and their close relatives, rooks, dropped stones into a tube of water to bring a floating treat within reach.

Some birds even chose heavier objects that sink over light ones that float, suggesting they understood what would work.

Continue reading: Chapter 5 of 5 →