What would you say if I told you that a reduction in the jaw size of humans was our single most beneficial evolutionary change when talking about human's rise to control the world? Study of the human skull can help to determine many factors revolving around evolution. Skull size, commonly determined by jaw size, is a great indicator of how closely related an extinct species is to humans.Humans have small jaws and a large braincase. In contrast, apes have a small braincase and large jaws.. Since apes and humans are so closely related, how and when did this change in jaw and skull structure change and what implications did this change have on all species?
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The above picture is a great example of the variation of skull and jaw size between humans and apes. Apes' huge jaws actually inhibit the ability for the head to grow. Humans, having very small jaws in comparison to apes, have a far bigger cranium.
Photo Credit: UPenn.edu, Linguistics 101, http://www.ling.upenn.edu/courses/ling001/com_bio.html |
Photo Credit: Webmaster, Evolution.
Skull and jaw size are great indicators on when these fossils were found. As noted before, earlier primates had very small skulls and huge jaws. The jaws were large to chew tough, raw food. These large jaws actually inhibited skull growth, which was a fatal flaw for these creatures. At some point a change in diet to cooked food caused the large jaw to not be a necessity anymore. These smaller jaws allowed for bigger skulls, bigger brains, and more technology to be developed. The smaller jaw can be argued to be the greatest piece of human evolution. Not only did a smaller jaw allow for skull growth, it allowed for language to be more easily spoken, as well.