The Purpose of Toes

What are toes good for? Compared with fingers, which allow us to manipulate tools, toes are usually thought of as inessential digits, good for traction and balance and not much else. But David Carrier, a biologist at Brown University, thinks toes deserve more respect. To him they are the gears in the engine of the human body, letting us walk and run with exquisite efficiency. Carrier’s analogy between cars and people is surprisingly precise. In a car, the engine is most effective when the pistons are pumping at a certain rate and the crankshaft is spinning in a certain range of revolutions per minute. Above that range, the pistons don’t transmit force as well, and the extra revolutions just waste gas without increasing the car’s speed much. Gears solve this problem by changing the ratio between the speed of the engine and the speed of the wheels. Shift up to ...