Chapter 5 (Kwasi Obeng-Dankwa)

Chapter 5 begins with an explanation of an experiment carried out by Harvard Psychologists. It involved the scientists naming playing cards as the experimenters flipped them face-up. Some of the cards were doctored in order to trick the students. When it was quickly flipped, the experimenters did not see a difference in the cards and saw them as normal. However, as it was flipped slower, they saw the difference and were baffled. The results of this experiment influenced Thomas Kuhn who used it to explain the term "paradigm shift(93)."We are then introduced to Jan Zalasiewicz who, along with Kolbert, are looking for layers of rock that are 445 million years old and date back to the Ordovician Era. The graptolite is then introduced to us and we are told about how dominant v-shaped graptolites used to be yet 444 million years ago they started to die out. With Alvarez's theory being validated, scientists started to wonder if other catastrophes had occurred. It was initially believed that glaciation killed off many species. Another argument made by scientists was that 252 million years ago, a sudden increase in carbon dioxide levels led to a mass-extinction. Finally,  Zalasiewicz’s theory of giant rats is brought up. This theory was that humans had brought in a new era of mass extinction.

I can connect this chapter to all of the previous chapters because of Thomas Kuhn's paradigm shift. For example, whenever a new discovery was made, it was made sense by using familiar knowings even if it did not make sense. It took the courage of a few people to go against normal understanding and bring about new theories that greatly contributed to science. However, when they did first introduce their ideas and findings, they were usually ridiculed for it and were widely unaccepted. This includes Cuvier introducing the paradigm of extinction, Darwin's theory of evolution,  and Alvarez's theory of the asteroid. Without these paradigm shifts, we would not be as knowledgeable about our Earth and what happens to the organisms that live on it as we currently do. This chapter also connected very well with the theme of humans alter natural systems. In the last few pages of the chapter, human effects on the world were listed out loud and clear. For example, it said " Most of the world's major rivers have been dammed or diverted... Humans use more than half of the world's readily accessible freshwater runoff(108)." It went farther to have a name for the time period we are in, which is the Anthropocene era. This chapter expressed the negative effects of humans on the planet more than any other chapter and I feel that it will continue to talk more about the negative effects of humans from this point on.