Bipedalism Evolution

Like people, but unlike apes, the bones of their pelvis, or hip region, were shortened from top to bottom and are more bowl-shaped (Lovejoy 1988). This made the pelvis more stable for support when standing or moving bipedally, as well as it allowed for the birth of large brained infants. The longer ape pelvis is adapted for quardrapedal locomotion. Modern humans’ centre of gravity lies over the feet and knees which lock. This allows the centre of gravity to sit between our feet allowing humans to stand on only two feet.

As was discussed in the previous paragraph, this bipedal aspect is what differentiates us, hominids, from modern apes. However, under the context of hominids in general and modern humans, it is this very trait that allows for us all to be categorized under the same label—hominids. Along the same lines as bipedal, another similarity between the two would be our arched feet—a characteristic that is unique to hominids, as it allows for standing and walking upright to take place. Both of these similarities—bipedal and arched feet—can be evidenced in the “Turkana boy” photo as well as the photo labeled “hominid/ape footprints.” As for differences, however, despite being quite similar in many ways, there are still a number of differences between hominids and modern humans, one of them being the size of our brains. While it is clear that with evolution came about more sophisticated and complex behavior due to the increase in brain use and size, when you compare hominid brains to modern human brains, modern human brains, by far, possess the largest and most complex brains, which is self-explanatory given the fact that while hominids were intelligent creatures, modern humans are far more advanced in their intelligence and capabilities.

This study examined the differences in articular surface morphology of caudal vertebrae between prehensile and non-prehensile tailed primates. Articular surface is skeletal surface, which includes bone and cartilage, that makes contact with other skeletal surface as part of a joint. Variation in the morphology of articular surface can confer a greater capacity for mechanical loading, which is required for prehensile primates as they often use their tails to suspend their entire weight during locomotion. In this experiment, it was hypothesized that articular surface area and curvature in caudal vertebrae could be used to distinguish between prehensile and non-prehensile tails. The results showed that articular surfaces found in both proximal and distal regions were greater in prehensile tailed primates, in comparison to primates that were non-prehensile tailed.

Extended and continuous upright walking had to be practiced for bipedality to be under strong selection. The necessity to carry food back for females would be to enough to force this kind of locomotion to become constant (Lovejoy, 1981). Males with reduced canines had an advantage because it signaled to females that they would not waste energy in dominance displays and could, therefore, spend more time provisioning for them (Lovejoy et al. 2009). The advantage of bipedality was that males could carry food back to the females.

It has a light skeleton for faster speed and its leg bones are longer in relation to the body size. They run on the tips of their toes while their spines are more flexible than other cats, letting them increase the size of their stride step. Their hip bones can hinge allowing them to stretch their legs further. These adaptations give a fast pace when running. For maintaining balance and to change direction faster and more precise, their long-narrowed well- muscled tail helps.

According to Walker-Pacheco (2010) hominins posses various characteristics that separate them from other primates, such as: bipedal locomotion and dental morphology. Most common

Therefore, evolution favors traits that promote genetic diversity because the conditions on Earth are always changing, and genetic variability provides organisms a better chance of survival than organisms that do not have genetic variability. 2. Describe a situation in which asexual

The other key development is hominin brain encephalization. As our extreme encephalization occurs after the onset of bipedalism we can assume that bipedalism was a prerequisite. The increased meat diet of the bipedal H. erectus coincides with increased encephalization. There are a number of theories as to why encephalization occurred. For example, using hands for toolmaking and other complex activities in turn selects for increased encephalization.

The biggest overt difference that one notices when comparing nonhuman primates to human primates is the loss of body hair in the modern human, to the extent even, that humans have been described as the “naked ape” in many contexts. The primates classified as old world apes that are closest in relation to humans are the Bonobos and Chimpanzees. Looking specifically at the Chimpanzees, we can compare and contrast the properties of the skin and hair between them and humans to get an idea of the evolutionary pressures that may have been in place. Notably, there are many different properties of the skin in the nonhuman and human primates. The dermis, or skin layer, contains various structures like nerve ending, sweat glands and hair follicles among other systems.

The more genes that contribute to a trait the greater the variation. Height is a polygenic trait in humans which accounts for the huge variation among the human population. Diet and health also play a huge role in the expression of height among people. Nilsson Ehle discovered polygenic traits through his wheat