Why Bipedalism?

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In early hominids, aspects of bipedalism were seen in quadrupeds. But why was there a change? Well, for one, bipedalism became a much more efficient way of walking compared to quadrupedalism. Because of our longer legs and new muscles like the gluteus maximus, we are able to take strides with our legs which uses less muscle and energy compared to quadrupedal knuckle walking as seen in gorillas. In the lab, we saw from station 2 that walking on all fours was much less efficient compared to on two feet as the average times were almost double for walking on all fours. Aside from walking efficiency, bipedalism may have evolved as the environment around it started to evolve. The environment in which early hominids lived in woodlands with high grasses and with bipedalism, they were able to stand up giving them a wider range of vision and freeing up their hands that could be used to carry items and tools. With the free hands, they were able to use tools and carry multiple items like food over longer distances. By becoming bipedal, we also were able to reduce heat absorption since less of the body is exposed to the sun. In station 3 of the lab, the flashlight, simulating the sun showed that bipedal locomotion has less skin exposure than compared to a quadruped. These advantages led to natural selection favoring bipedalism. However, even along with all these advantages; there are many disadvantages to bipedalism. One is that because we had to stand to walk on two legs, our pelvic bones became more bowl shaped compared to the elongated pelvises of quadrupeds. With that, the birth canal of female bipeds became smaller and because of increasing brain size, it made giving birth harder. However, to counter the increase in brain size and decrease in birth canal size, the baby skull of bipedal organism are not fused, such as humans. As a result, the head can be altered a little so
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