The oldest evidence for walking on two legs comes from one of the earliest humans known, Sahelanthropus. Walking upright may have helped this species survive in the diverse habitats near where it lived—including forests and grasslands. The upper part of this thigh bone is similar in size to those of other large apes. But the angled part more closely resembles that of modern humans. Every time you take a step, you briefly stand on one leg—putting stress on your leg bones.
The wide area of bone just below this the knee joint in Australopithecus anamensis is a result of that stress. It provides strong evidence that this individual walked upright. Fossils from around this time period come from early human species that lived near open areas and dense woods. Their bodies had evolved in ways that enabled them to walk upright most of the time, but still climb trees.
As a result, they could take advantage of both habitats. The curve of your lower back absorbs shock when you walk. It is uniquely human. You can see a similar curve in the spine of this early human, Australopithecus africanus , who walked upright in a way very similar to modern humans. The pelvis and thigh bones outline to right of Homo erectus are similar to modern humans, and show that this early human was able to walk long distances. That ability was a big advantage during this time period.
The long thigh bones of Homo erectus enabled its owner to take long strides and therefore to walk farther and faster than earlier humans. Compare a Chimp with an Early and Modern Human. Modern chimpanzees occasionally walk upright, but their skeletons are not adapted for regular walking on two legs.
Early humans evolved skeletons that supported their bodies in an upright position. Modern humans have bodies adapted for walking and running long distances on two legs. The spine of early humans connected with the skull underneath, stabilizing the head when walking upright.
Note: Content may be edited for style and length. Science News. ScienceDaily, 20 July University Of California - Davis. Retrieved November 11, from www. But a new study finds that water bears propel themselves through sediment and soil on eight stubby legs, in The fossilized The aim was to find easy coping Print Email Share. Boy or Girl?
Living Well. On average, the chimps used the same amount of energy walking on two legs as they did on four. However, one chimp, with a longer stride, was more efficient walking upright.
The team was able to attribute performance differences between the chimps to differences in the length of their stride and the amount of muscle they activated with each step. They measured the latter by having the chimps walk across a metallic force plate. Biomechanical equations predict that energy consumption increases either with shorter steps or more active muscle mass.
The chimp that used less energy walking bipedally did so because it had longer than average legs. We humans are able to reduce both factors because of our relatively long legs and modified pelvic structures.
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