Why are our hands the shape that they are?

Researchers at the University of Utah have a suggestion: The hand is the shape that it is because it allows us to make a nice fist for fighting that protects key parts of the hand from harm. The proposal was made by student Michael Morgan and biologist David Carrier. The duo tested their hypothesis in a series of experiments in which men pounded punching bags, squeezed pressure sensors or performed one-handed push-ups on top of pressure sensors. From this, the scientists learned that force meted out by the hand is about the same when a bag is punched by a fist versus slapped, but nearly twice as great when you consider that the fist delivers its force to a smaller surface area. The study also found that the knuckle joint of the index finger is rendered stiffer and more stable - transferring force more effectively and protecting the hand - when a tight fist is made. In other words, the fist is a dandy fighting tool.