The Encephalization of Primates

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The Encephalization of Primates: Size Matters
A crucial turning point in Primate history took place 2.6 million years ago when various selective pressures led to the encephalization of Hominins. The ice age quickly approached this time period and thus resulted in a struggle of adaption and survival for many animals on earth. This took a particular impact on early hominins; Hominins during this time lived in Africa and thus were affected by the Ice age in a completely different way. Africa, instead of becoming colder, became much hotter as result of the frozen oceans, which created a dry savannah environment. In addition, many primatologists as well as archeologist agreed that the savannah offered both a dry but stable environment. The need to adapt to the new environment resulted in both the extinction of primate species as well as the encephalization of homimins. The accelerated growth of the hominin brain allowed them to acquire skills that would permit them to adjust to the changing world and some examples of these new adaptations included the use of stone tools. Stone tools are attributed to this era and it can also be inferred that these were used during the incorporation of meat to the hominin diet. Hominins, 2.6 milllion years ago began to consume meat as result of scarce fruits and leaves in their new environment. It is theorized that the stone tools were first used to cut animals apart and extract marrow from their bones, while more sophisticated tools later were used for hunting and making clothes. Although the real explanation for the accelerated brain growth of early hominins is uncertain, most primatologist agree that larger brains are energetically expensive and that their diet contributed to this greatly. Paleontol...

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...fruit and leaves had a substantially bigger rib cage than that of a humans who eat meat. It was also noted that tool use was easier with a narrower rib cage than a wider rib cage and this supports the theory that hominins incorporated meat to their diet (Aiello and Wheeler 1995). As noted, tool use approximately 2.6 (mya) could be liked with the consumption of meat and the expansion in hominin diet would explain smaller gut size. Meat is much easier to digest therefore the body has to work less to process the food and as result it can be concluded that the brain took the extra energy that smaller gut did not use. Overall, the expensive tissue hypothesis claims that the adoption of a high quality diet such as the incorporation of meat explains the reduction of the gut, which reduced the energy intake of the gut and fueled the encaphilazation of the hominin brain.

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