A: Dogs, says Canadian psychologist Stanley Coren in "What Do Dogs Know?" In the United States alone, more than 50,000 of them were enlisted and ended up at one of five War-Dog Reception and Training Centers. In addition to the above, many canines were trained for delicate and dangerous tasks such as mine detection; their special importance lay in finding non-metallic plastic mines in North Africa, since these devices were completely invisible to traditional magnetic mine detectors.

Perhaps their most exotic occupations were as spies or infiltrators into enemy camps to steal documents. Before it was all over, "almost all breeds of dogs had been drafted by the U.S. Army."

Q: What can the rider of a wild bull (or even a mechanical bull in a bar, for that matter) do to help stay mounted other than just holding the strap around the animal's chest?

A: With each sudden move of the bull — twisting, pitching, running, stopping — the rider's momentum and angular momentum tend to send or rotate her from her perch, says Jearl Walker in "The Flying Circus of Physics." Instead of holding on to the strap tightly with both hands, she can do better by throwing one arm high, far from her rotational center, in a direction to counter any sudden rotation of the more massive upper body of the bull. If she also holds a large hat with her free hand, the air drag on the hat as it is waved might give an extra measure of resistance to the rotation of the upper body.

A first-time roller or ice skater does something similar to partially correct a problem with imbalance. "During my first time on roller skates, when the skates tended to roll out in front of me, I automatically rotated my arms in vertical circles back over my shoulders (like a windmill) to keep my center of mass positioned over the skates and thus to maintain my balance and what little was left of my pride."