Crows Understand Cause and Effect, Even When the Cause is Hidden

For the New Caledonian crow, birdbrain is a misnomer

: These members of the corvid family have proved their problem-solving

and tool-wielding

abilities again and again

. The birds may have yet another impressive cognitive capacity, a new study suggests: causal reasoning. The ability to link an event with the mechanism that caused it, even if that mechanism is hidden, is the basis of modern science---and our most basic knowledge of the world around us. If New Caledonian crows are capable of causal reasoning as well, we can better trace and understand the evolution of this ability. Researchers described how they tested the crows' reasoning

in the Proceedings of the National Academy of Sciences. First, they let eight New Caledonian crows figure out how to use a tool to remove food from a hole in a box. Then the experiment began. The crows watched as a human entered their enclosure ...