Sunday, January 23, 2011

Teeth - Why We Lose 'Em and How Other Animals Are Different

Why do we lose our teeth as kids?  It's such a common occurrence that unfortunately we don't really stop to think about the evolutionary implications.

The conventional wisdom is that we need bigger teeth as our jaw gets bigger.  Well, why don't our teeth just get bigger then?  They could certainly grow if they wanted to.  Doesn't it seem like an energetically profligate endeavor to build teeth just to toss them away?  Yes, it does.  So, why?

After having those thoughts my mind had an exciting jump: maybe it's an evolutionary tie over from when our ancestors teeth shed all the time!  

It's not quite that simple, but with a little web research found that there's lots to learn about teeth that I had no idea about!  Enjoy the below!

Different Teeth Growth Strategies:

1 Set of Teeth Called Monophyodonts - Rabbits/Lagomorphs and Toothed Whales

2 Sets of Teeth or Diphyodonts or Those with Deciduous Teeth - All Mammals, with a Few Exceptions

Polyphydonts or Those with Multiple Sets of Teeth - Reptiles, Amphibians, Fish, Manatees, Elephants

Alligators (croc above) can  have 80 teeth at once and go through 3000 teeth in a lifetime.

Manatee jaw with 'marching molars' that come in in the back and drop out towards the front.

Not the greatest picture, but this shows a mammoths 'marching molars' slowly emerging from deep within the jaw.

No Teeth! - Baleen Whales, Ant and Termite eating Pangolins and Anteaters

No teeth here!  Just baleen!

No teeth here!  Just tongue!

Toothless pangolin skull

Toothless anteater skull
The Most Neurologically Complex Tooth: the Narwal.  The tooth is multipurpose and is used in feeding, navigation and mating.

Longest Tooth - Straight-Tusked Elephant

Heaviest Tooth - Columbian Mammoth

Gene Found in Chickens that Inhibits Tooth Growth .  Best part of this: it can be turned off and chickens can have teeth.  

Pictures from here, here, here, here, here, here, here, here, here, here, here, here, and here.

Works sighted [sic]:


  1. Hah. I love your blog. Biology is the best!

  2. Isn't, though? Life gives me life!


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