Chapter 5 by Andrea Guinanzaca

In chapter 5, the chapter begins with a famous experiment that took place in 1949,  in which students were asked to name a series of playing cards as the experimenters flipped them face-up. This experiment served as an important influence on the thinking of the great science historian Thomas Kuhn. Kuhn argued that, throughout history, human beings are forced to adapt to changing environments. Kuhn’s ideas about paradigms helped through the study of the history of evolutionary science. During the Ordovician era, sea life grew rapidly and the first coral reefs were formed. In the middle of the Ordovician era, moss-like plants appeared on land. Around 444 million years ago, something happened to the graptolites that made them have V-shaped, bodies an evolutionary disadvantage. In this particular part of the chapter, this connects back to how after the Alvarez's published their paper on the asteroid that wiped out the dinosaurs, scientists slowly began to rethink their ideas about extinction. If an asteroid could explain one "fossil gap," perhaps other catastrophes could explain other fossil gaps. Some scientists argued that the periodic gaps in the fossil record could be explained by the presence of a small "companion star" that periodically showered comets on the Earth’s surface, destroying almost all life.

Later in the chapter, Kolbert’s goes to Scotland. In Scotland, she learned about Zalasiewicz theory of giant rats. The result is that rats are among the most resilient creatures on the planet. There's a prediction that rats will most likely be the only species to survive from a mass extinction. The logic of Zalasiewicz theory of giant rats is that humans have ushered in a new era of mass extinction. Paul Crutzen, another scientist introduced in this chapter,  coined a term in 2000. He argued that humans have fundamentally changed their planet in several ways Here is the list of how humans changed the planet: 1) humans have majorly transformed almost half of the world’s land surface; 2) humans have either damned or diverted the majority of the world’s rivers; 3) human agriculture has dramatically increased the amount of nitrogen in the atmosphere; 4) humans have eliminated more than a third of the primary marine life of oceans’ coastal waters; 5) humans consume more than half of the world’s available fresh water; 6) humans have dramatically changed the composition of the Earth’s atmosphere by releasing carbon dioxide and methane gas. In conclusion, this part of the chapter supports Kolbert's argument that our actions will cause a mass extinction.