Introduction to Bipedalism: Why Bipedalism?

Habitual bipedalism is not necessarily the fastest and most effective form of running or walking, but bipedalism has a number of advantages over certain specialized forms of quadrupedalism. It is not clear why certain hominins may have adapted a bipedal behavior, though there are many varied hypotheses constructed around the idea that environmentally-based selection pressures operated to drive the evolution of bipedalism^8-10,12-14. Some of the older ideas about the advantages of bipedalism include: the ability to carry food or other portable items over longer distances; the freeing of forelimbs for foraging, tool use or protection; moving in a more energy-efficient manner than other forms of primate quadrupedalism; long distance running; and the acquisition of improved long-distance perception. Another possible explanation for bipedalism is that it is an adaptation to efficiently cool the body in hot temperatures, known as thermoregulation. In a hot savanna environment a tall, lean upright posture exposes less surface area to heat of the sun but allows more heat to escape from the sides of the body because more surface area is exposed to cooling wind and air.

Even though no consensus has been reached by the scientific community about these ideas, many if not most of these possibilities are not mutually exclusive, and some combination of these different selection pressures may have been responsible for driving the evolution of bipedalism.