Chapter 4: Teeth

This chapter, after first, was not at all all appealing. It wasn't until I read about the Ostracoderms that I became interested. I can't believe it's head was made up of teeth! That's so bizzare. I never really thought about teeth, other than the fact that they were, well just teeth. The way Shubin reveals the history of teeth and how it is a key element in discovering more about ourselves really catches my attention. To be honest, I don't really care about Shubin's past experiences, but so far, he has never failed to impress me with the way he ties his experiences and what he learned to teach the reader about his origins. When Shubin makes such a connection between his experiences and pure boring facts, it takes biology to a whole new level of fun and makes biology so much easier to picture/relate to/ understand.

I learned that our teeth is the hardest part of us as it has many layers (enamel, dentine, hydroxyapetite) . I also learned that we have different sets of teeth used for different functions. For example, the teeth in the front are used to cut, and the teeth in the back are used to grind, the teeth in between have a mixed function of both.

I also want to give props to Shubin for helping the reader connect chapters 1, 2, 3, and 4 as he explicitly tells us the underlying theme within those opening chapters. Basically, every part of our body has an older version and we can trace every single one of those parts back to ancient mammals that first had these features. Understanding the theme helped me connect and make sense of all these stories and words Shubin throws at me; I feel as if he's really guiding me through his book, making sure that I understand every point he makes and why he makes that point.

- Ejay Yuan