Rat teaches me to feed her when she tattles her tray. But I won't do it until everything's been eaten, also the boring bits. Then suddenly for weeks no trouble whatsoever - when she rattles her tray, it's empty, everything gone. Until one night, hidden behind a doorpost, I watch her methodically clean out the boring bits and bury them under floor pellets. As soon as the tray is empty - rattle rattle rattle. This was a supremely gifted individual. She performed similar strategems towars her cage-mates, for the most part successfully.

Oh, and I always wondered what all the fuss was about with the Japanese macaque monkeys and their cultural transmission stunt. I saw one rat getting inventive with the drinking water tap, beginning to take water with cupped paws and use it for washing her fur. Others picked up on that habit, and yes, it spanned generations.

> Others picked up on that habit, and yes, it spanned generations.

It's memes (in the evolutionary sense) all the way down.

How do you know it's deceit? It seems like you could get similar behavior if you filled two trays, one with food and the other with trash, and never provided food unless the trash tray was empty. You're training the rat to empty the tray.

Not quite. She realised I could be tricked, but only if she thorougly covered her traces. I watched the thing. It was so clearly reasoned behavior.

It didn't just empty the tray. It hid the food. That does imply it took an extra step based on a mental model of the situation.