For 200,000 or more years, the fine-tuned mechanics of human motion have enabled our species to traverse enormous distances on foot with remarkably little energy expenditure. Scientists have long pondered which specific qualities of walking and running render those means of getting around so efficient.
Now, a pair of biomechanics theorists say that they've captured the essence of what makes human locomotion as thrifty as it is. Their model explains why any number of silly-looking gaits, such as the crouching strut of Groucho Marx, tire us out more than routine styles of perambulation do, says Manoj Srinivasan of Cornell University.
The analysis by Srinivasan and Andy Ruina, also of Cornell, offers a new "conceptual framework" for human locomoti