hips to a greater degree and took a more upright posture, closer to that of humans, were able to save more energy than chimpanzees that did not take this stance. Further, compared to other apes, humans have longer legs and short dorsally oriented ischia (hipbone), which result in longer hamstring extensor moments, improving walking energy economy. It was thought that hominins like Ardipithecus ramidus, which had a variety of both terrestrial and arboreal adaptions would not be as efficient walkers, however, with a small body mass A. ramidus had developed an energy efficient means of bipedal walking while still maintaining arboreal adaptations. Humans have long femoral necks, meaning that while walking, hip muscles do not require as much energy to flex while moving. These slight kinematic and anatomic differences demonstrate how bipedal walking may have developed as the dominant means of locomotion among early hominins because of the energy saved. Variants Scrambling is a method of ascending a hill or mountain that involves using both hands, because of the steepness of the terrain. Of necessity, it will be a slow and careful form of walking and with possibly of occasional brief, easy rock climbing. Some scrambling takes place on narrow exposed ridges where more attention to balance will be required than in normal walking. Snow shoeing – Snowshoes are footwear for walking over the snow. Snowshoes work by distributing the weight of the person over a larger area so that the person's foot does not sink completely into the snow, a quality called "flotation". It is often said by snowshoers that if you can walk, you can snowshoe. This is true in optimal conditions, but snowshoeing properly requires some slight adjustments to walking. The method of walking is to lift the shoes slightly and slide the inner edges over each other, thus avoiding the unnatural and fatiguing "straddle-gait" that would otherwise be necessary. A snowshoer must be willing to roll his or her feet slightly as well. An exaggerated stride works best when starting out, particularly with larger or traditional shoes. Cross-country skiing – originally conceived like snow shoes as a means of travel in deep snow. Trails hiked in the summer are often skied in the winter and the Norwegian Trekking Association maintains over 400 huts stretching across thousands of kilometres of trails which hikers can use in the summer and skiers in the winter. Beach walking is a