Tools for thought or thoughts for tools?

B ird and Emery report in this issue of PNAS (1) that rooks (Corvus frugilegus), corvids that do not habitually use tools in the wild, appear to possess tool-related capabilities hitherto known only in their tool-using relatives, the New Caledonian crows (Corvus moneduloides) (2–5). Their findings are striking in more than one respect, but it is of particular interest to evaluate their significance for theories about the influence of tool use in the evolution of intelligence, for recent arguments against the value of evolutionary thinking in relation to cognition (6) and for that old nugget, the use of metabehavioral concepts such as insight as causal explanations for behavior.