Strength—the ability to produce force. An often valuable, sometimes invaluable, tool in the evolution of our species. These days, men and women test their strength not against predators or other aspects of the natural world but against various types of weights. Around the world there are many sorts of strongman competitions—such as the Highland Games in Scotland and various “Strongest Man” events. These two sports use iron weights very little, using instead objects found in everyday life, such as log poles (cabers), hammers, boulders, farmcarts, barrels, axes, planes, and trucks.