YIF: Chapter 4

            This chapter encompasses the evolution of animals by taking the perspective of teeth. The evolution starts at conodonts, then, ostracoderms, all the way up to humans. Teeth are a powerful window into an animal’s lifestyle, especially their diet. Also the author talks about teeth and how they are preserved well and why, which is because teeth contain something called hydroxypatite. This is why teeth are more preserved than other bones and tissue. The evolution history of humans can be explained by something as small as teeth because of the type of teeth, their size, and their alignment. For example our mammalian way of precise chewing, emerges in the fossil record from around the world that ranges from around 225 million to 195 million years ago. My favorite part of the chapter was the largest portion of the chapter; it was the story of the author’s first expedition and the first two expeditions that he led with his colleagues. This story was well written and grasping and intriguing, after each page that I read, I wanted to react more because it was intertwined and showed a progression in wisdom and experience. It made it seem realistic and the effort that was put into the expeditions could be easily seen. Also I love how he sets up each expedition is a many story by making a sort of suspense by talking about his failure, what he did to improve and then him getting better, and then finally him finding something special to both him and something that is very relevant to the purpose of the book. The Big Idea of biology that makes a connection to this chapter is the same as all the others, and that is the process of evolution drives the diversity and unit of life. The reason being is that once again this proves that multiple animals that are seemingly different can be classified in the same category as humans due to a common ancient ancestor. One essential question that can be made for this chapter would be, “How can mammal teeth show the relationship between two species?”