A Matter of Diversity--Our Teeth Size and Shape

          Now that we've had a brief introduction about the overall importance and factors leading to the evolution and changes that can be witnessed in the dentition and oral development of humans, let's take a closer look a some particular topics. For today, I thought to focus on teeth size and shape. It is common knowledge that the sizes and shapes have been changing with time and across cultures, but how? And, by how much? What impacts have these changes produced on our society? Personally, I feel the evolution of human diet and the progression of agriculture provides one of the most influential roles in just this.
         
          Teeth size and shape are heavily correlated with one another and thus impact each other a lot as well. As the species of hominids diverged from previous ancestors, dentition has been seen to increase in complexity, which means more individual teeth and not only one or two molars.
          Mammals have distantly evolved from reptiles, and one of the key components in separating us two species was the development of temporal fenestrae enabling more jaw muscles to form and stronger bites. These holes in the skulls have been modified as the years and humans evolve.

http://tolweb.org/notes/?note_id=463

 This development alone meant that mastication (chewing and grinding) would become more effective reflecting the dietary changes all mammals and reptiles were facing.

Yet, even more diversity among mammals was able to occur. This was caused by changes in "cusp number, morphology, topology and orientation are species-specific. Those disparities are due to differential, spatiotemporal cell multiplication and programmed cell death of the inner enamel epithelium cells during embryonic and post-embryonic development"

http://www.studiodentaire.com/en/glossary/cusp.php

With time, cusps of human became more low, along with the development of larger and "flatter" teeth resulting in more molars and less canine teeth present. Ignoring geographic variation, humans were shifting towards a less carnivorous diet meaning different parts of the teeth would be used to masticate food. Larger teeth in the back of the mouth consume tougher foods, such as fruits, whereas smaller teeth in the front are used for food requiring less extensive incisal preparation including leaves and berries.

          Specifically to teeth size, there is a direct relationship between the size of the individual and maxillary central incisor (you're two big front teeth). This correlation is key to understanding that as the human species grew and became more complex, as did their dentition.

          That is all for today folks, but check back for updates on the evolution of the four different division of our teeth: incisiors, pre-molars, molars, and  canines!

Ta-ta for now

http://www.you-can-be-funny.com/FunnyDentalCartoons.html