Teeth: The Great Evolutionary Debate

Greetings everyone and welcome to the Shadow’s Lair. In this episode of “Koraki’s Vlog” I will discuss where teeth come from. First let me introduce myself to those who might be new to the channel. I am Koraki, a fantasy author, disability advocate and geology enthusiast. Today I am going to talk about teeth.

You probably have teeth, or had them at some point in your life, but have you ever wondered how teeth evolved? There are two main hypotheses I will discuss on the evolution of teeth. Before that though I want to touch on another favourite subject of mine- etymology.

The Etymology of the word tooth comes from the old English tōth. This is from the Proto-Germanic tanthu. This from the Proto-Indo-European dent which (I must clarify according to Wikipedia) means “that which eats.” (While I am not keen to cite it as a source, I found this tidbit in the wiki on teeth interesting.) (2,4, and 5)

There are two theories to the evolution of teeth. The “outside in” and the “inside out” theory. In simple terms, they describe how teeth evolved in concurrence with our skin and jaw. The outside in states that teeth evolved from our skin as outer denticles (dermal armor). The inside out theory states teeth evolved from the endoderm (internal skin) of the throat (as pharyngeal teeth) in jawless fish. (1.3.)

There is a third hypothesis which I am not as familiar with. This theory states that the neural crest gene regulatory network and ectomesenchyme are important to tooth generation regardless of the endo-ectoderm (inside or out) theories. I deduced this to mean that teeth didn’t evolve as either or the other, but from both mechanisms. (1.5.)

I was inspired to write this because a friend of mine referred to teeth as mouth bones and this is inaccurate. No matter the hypothesis on how teeth evolved the only conclusion on what teeth are (in my opinion) is: They are hardened mouth skin. Anyway, I hope you found this interesting. As always, there will be links to my sources in a document linked below. Thank you for watching and please don’t forget to like and subscribe.

Citations and Resources Used

  1. Jheon, A. H., Seidel, K., Biehs, B., & Klein, O. D. (2013). From molecules to mastication: the development and evolution of teeth. Wiley interdisciplinary reviews. Developmental biology2(2), 165–182. https://doi.org/10.1002/wdev.63
  2. Merriam-Webster. (n.d.). Tooth. In Merriam-Webster.com dictionary. Retrieved January 31, 2023, from https://www.merriam-webster.com/dictionary/tooth
  3.  McCollum, M., & Sharpe, P. T. (2001, April 6). Evolution and development of teeth. Journal of anatomy. Retrieved January 31, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1594990/
  4. Online Etymology Dictionary. (2019, March 12). Tooth (n.). Etymology. Retrieved January 23, 2023, from https://www.etymonline.com/word/tooth#etymonline_v_15372
  5. Wikimedia Foundation. (2023, January 30). Tooth. Wikipedia. Retrieved January 31, 2023, from https://en.wikipedia.org/wiki/Tooth#:~:text=Teeth%20are%20assumed%20to%20have,inside%E2%80%93out%22%20theory).    

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