Anthropology: Pelvis and Larger Brain Mass Essay

Scott Stiffler
Anthropology
Dr. Kenny
1st March 2013
Evolutionary Traits of Humans The debate about evolution can tend to be a very heated one. When looking at our history it can be hard to look at it objectively. Often we have some preconceived notion as to where we came from or how we came to be who we are today and there are many theories to offer answers to these questions. However, anthropologists have found evidence that appears to conclude that we did evolve from an ape-like ancestor. These clues have come in all forms, sizes, and shapes. But, some of the most striking and hard to ignore clues have come from the archaeological record. Bones, tools, and even diet clues have been found in Africa that suggest the presence of an early human-like species, known as homonins. Some of the biggest clues have come in the form of tool-making and genetic indicators. With the evidence we have uncovered we can reasonably say that these early homonins are related to humans in some way based on the genetic importance of their skull and pelvic bones as well as what can be inferred from the tools that have been found. In understanding the evolution of humans we can look to certain changes in the genetic lineage and see certain trends that can answer questions as to how humans came to be like they are today. The first instance where genetics can help us understand our modern selves is the transformation to bipedalism. Bipedalism is the ability to walk on two legs. This is significant since our early ancestors walked on all fours but then made the transition to just two legs. The earliest genetic evidence we have of this are a difference in pelvic bones. If you look at an animal's pelvis that walk on all fours it is very different since the legs are positioned at more of a right angle than a flat 180 degrees of the bipedlaism. The different pelvic bones can be seen in the size of the ilium bone. The shorter human ilium is broader which helps with stabilization issues that a quadraped would not have to deal with (205). So if we compare a bipedal pelvis to a quadrupedal pelvis, we see that the human pelvis is much shorter and wider to help accommodate for the extra stabilization need since we don't have an extra two limbs to help us out. Since there is evidence that the pelvis has changed from a 4 limbed stance to a 2 limbed stance then we can see the transition needed to occur to become modern humans. Genetics can further help us understand our ancestors if we look to the brain. If we look at monkeys, chimps, and apes today we can see that they have a very high brow and little forehead. This suggests that they do not have to accommodate for a larger brain mass. When looking at early homonins there begins to be an elongation of the forehead, or a dropping of the brow. This is to suggest that there is need for the human bone structure to change in order to allow the growth of a bigger brain. In order to house a more developed brain we must have room for it. When looking at early homonins we see that this effect has not fully taken place, however, there is evidence that the forehead and brow are changing in order to allow the development of a larger brain mass. Therefore, if we understand that the our early homonin ancestors didn't quite posses the same brow as humans today, but they were beginning to develop a larger forehead, then we can infer that this means the development of a larger brain mass. No other animal has the same type of forehead as humans due to the lack of need for one. This means that we can reasonably deduce that these were our ancestors since they illustrate the needed change in our forehead and brow to accommodate for our larger brain size. This is then combined with the lack of a protruding face. modern chimps and apes have faces that protrude out, they are not like humans who have a very flat face. When looking at the fossils of early homonin they too have this flat face that does not protrude. This is

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