We've all heard of Pavlov's dogs, but have you heard of Mizunami's cockroaches?

Scientists in Japan have conducted their own Pavlovian experiment, but using cockroaches. They exposed a group of cockroaches to a particular odor every time they gave them a sugar solution to feast on. Later, when they exposed them to the odor alone-no sugar solution in sight-the little devils drooled.

Their control group was given the sugar solution without being exposed to the odor. When this group was later exposed to the odor alone, no sugar solution, they produced no more saliva than normal.

This experiment is interesting in that it has shown that even very simple-brained creatures, like cockroaches, can learn and remember.