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

 

Welcoming Our Ancestors

          Much of what we have today we take for granted. One such thing is our bodies. The subtle beauty of adaptation and evolution we as a species have undergone exhibits far more than just natural selection; it demonstrates our capability to become better, stronger, and faster. Yet, why do we still see prevalent cases of illness and disease inflicting the human society? Why do many people ALWAYS cavities and others never in their lifetime? Is there more light that needs to be shed on cross-cultural difference in oral health? WHY do we grow wisdom teeth only to far too often have them pulled out? Heck, why do we have so many teeth instead of two nice big ones?

The easy answer to the above questions and many more is:

to understand our present and future, we must inevitably rediscover our past.

So, because we need to become familiar with some old friends, I'd like you say hello to my pal Ardi!

http://www.macridesweb.com/life/NationalGeographicHO.html

This fella' (above) is the earliest hominid uncovered, and has been heavily used as the basis of many scientific research and comparison to modern humans and human evolution. For the purposes of this blog, we will be focusing on Ardi's and his relatives' oral, jaw, and dentition structure, composition, and function.

          From Ardi's profile, we can easily deduce that there are many immediate similarities between him, myself, and you, but there are also some differences. As we zoom in to his facial features, there are a few other things to be keeping in mind.
          As a Hominid, Ardi was witnessing the emergence of the most primitive forms of tools and technology. Cooking, for example, dates back over 250,000 years ago. This was perhaps the most direct and immediate cause in jump-starting the road to dentition evolution. In addition to cultural evoution, human evolution had been progressive. Because evolution encompasses an array of factors that heavily impact the fundamental existence of mankind, let's focus on a holistic view of what was happening.

          Beyondveg.com effectively shares an understanding of our ancestors' dentition and jaw structure during the age of Hominids. The interesting point made within the article is how dentition has shrunk as the human species became more evolved. This decrease of our teeth and jaw structure was caused both by, as we mentioned earlier, cultural and evolutionary influences. Below, I highlight the key components of the article that explains why this occurred. 

Cultural Impact:

There is a linear relationship of decreased dentition and increased use of tools (stone tools/fire) and meat consumption.

•  More meat consumption means less coarse veggies eaten, so less teeth needed to grind them!

http://www.jqjacobs.net/anthro/paleo/images/dentition.jpg

•  Cooking especially made it easier to chew food, thus from the above image, reduced canine teeth and increased the presence and significance of our molars. This "relaxed" dentition demonstrates robust anatomy. From my ANTH course, we learned that robust hominids were a muscular species as well as heavily vegetarian, with some originating from Australia: a diverse continent of plants and fruit.

Biological Impact:

It is clear that the purpose of the mouth serves multiple functions and is interconnected with other parts of the body. In particular, are brain size and the development of language.

The increase in brain size, encephalization, and bipedalism of humans caused a shift in pressures of the mouth changing the shape of the mouth from being a long "U-shape" to a flatter "U-shape".

Humans are the only organisms to produce complex speech patterns. Coyotes howl, horses neigh, and cats meow, but the infinite sounds we can produce are from the patterns and stops within our mouths. This begs the question, "What's the relationship between language and the consumption of cooked food?" Evolution must have been working overtime to account for these two major changes.

• "Air, liquids and solid food all use a common pathway through the pharynx". Thus, humans are more likely to choke than other animals. 

• The reduction of the roof of the mouth and lower jaw decrease efficiency of chewing. So, chew more at your next meal!

• Reduced dentition has caused crowding of teeth and more likelihood of infection (see future blog-post)

 Was there a tradeoff between language and oral health? Clearly not a large enough one considering communication in today's world is imperative. Nonetheless, natural selection recognized this importance and allowed humans to adapt language, dentition, and brain size to optimize our existence.

http://www.beyondveg.com/billings-t/comp-anat/comp-anat-6b.shtml

As I wrap up this pretty long blog post, it's clear to see that multiple factors have played in the physical development of our jaw structure and dentition. While we briefly looked over the holistic view of the influences environment and culture have played in oral system's evolution, it is critical to take a step closer and look at the specifics of what within our teeth truly changed, and how ultimately these changes have impacted the lives of present and future Homo Sapiens. 

Until next time,
Lators Gators!

http://www.asu.edu/courses/css335/images/Jack%27s%20broken%20crown%20cartoon.gif

         
          

A First Impression

Good evening!

My name's Manmit and I'm super pumped to be blogging about the amazing field of....dentistry! As I try to control my excitement, I'd like to share with you all a bit about myself. I'm a pre-dental student at the University of Illinois Urbana-Champaign (go Illini!) and am actually starting this blog for my ANTH249: Human Evolution and Disease course. So far, this course has been the push I needed to become more actively involved in my future career aspirations. Why is dentistry for me you ask? Well, it is often a common assumption  that I am a pre-dental student for the money, lifestyle, prestige, etc. While that may be true to a certain degree, I more so appreciate how oral care has evolved a great deal due to advancements in medicine and changes in lifestyle. Oral health and dentition, in particular, are often the first elements of the body to show signs of disease and infections occurring throughout the rest of the human self. To understand our teeth, is to understand the human body. By understanding the human body, it is easier to recognize other problems that may exist, and how to treat them. In evolution, everything is interconnected. I was worried this may make it difficult to narrow down to a topic to research on, especially in oral health and evolution, but I have been able to set a clear track of what my project will explore during the next couple of months. 

My goal is to research and be able to inform you all on the evolution of humans’ jaw (and other oral structures’) anatomy/ physiology and how the impact of diverse lifestyles can promote or prevent oral diseases. Ultimately, the significance in acknowledging these changes should ideally promote better care of oral health to eliminate and prevent oral diseases—a glimpse into treatments used in the past (plants) and now (medicine) is a comparative approach I will utilize to strengthen the importance of oral care. I feel that my project will be greatly welcomed my the blogging community; from my blog posts so far, I have read the numerous comments in which my other peers have become quite intrigued in the subtle but influential role of oral and dentition evolution in humans.

As a student, I am limited in what and with whom I can experiment or perform “research” on. So, primarily I will rely on resources such as blogs, online databases, books, etc. for research. In my research I have conducted so far, I have been astonished in how many studies have been performed and research that has been conducted and collected, by universities, blogging individuals, and even dentists themselves. I will gather background information about the oral structures of our ancestors during different periods in time in different parts of the world. I will note general trends and unique patterns to particular populations. I will then share the medical diseases, if any, in existence at these times and places, as well as remedies and the diet employed. Then I will share the same information, but from today’s circumstances. It will be quite unique to compare more developed countries with less developed countries, and a select few indigenous tribes such as Eskimos, natives from the Amazon, Africa, and Asia and explore the differences and similarities that exist in their teeth. It is important to appreciate the diversity geography itself has to offer in physical appearance and human evolution. Additionally, if I come across any hypotheses or theories related to these topics, I will discuss them. Overall, it is important for me to learn and eventually inform the class of the evolution of dentition and oral growth and development and changes in infectious and oral autoimmune diseases and relate them to my readers in an effective and personable manner.




I hope you stay tuned and join me on this thrilling journey!