The Sixth Extinction: Chapter 3

Chapter Three explores the idea of evolution and connects it to extinction. She introduces the idea of “catastrophism” that William Whewell used as an insult to scientists, such as Cuvier, who believe that the planet came to be through catastrophes which affected the planet in several ways including the extinction of several animals. In response to this idea, Charles Lyell theorized that there has been no catastrophe of that sort, but instead the planet’s structure has slowly changed because of erosion. Because of these changes, some species gradually became extinct. This theory came to be known as “uniformitarian” and gained the support of Charles Darwin. After completing his studies in the Galapagos Islands, Darwin began developing his theory that will soon be famous for the idea of natural selection. The theory applied Lyell’s idea of gradualism into the development of species, species are in constant competition over limited resources meaning that those with better characteristics for survival will slowly take over causing another one to die out. Through time the species develop traits to help it compete but there can only be one winner because introducing a new species to an ecosystem leads to the gradual death of another. This all happens so gradually that humans haven’t been around to witness it happen meaning that when it happens, we wouldn’t know it since we barely even know how to recognize it. The golden frog is being put in danger by an invasive species so does this mean that them dying out and being replaced is natural? Well, we know that humans caused this crisis and according to Darwin, humans take part in the natural ecosystem, so doesn’t this make it natural? Well not quite because Darwin didn’t keep in mind the fact that humans are the only beings capable of single-handedly making a whole species disappear. At the end of this chapter, I was left super confused asking myself if rapid extinction caused by humans is natural or if it’s something that can distort the whole ecosystem. 

Once again, this chapter shows how the earth is a complex interconnected ecosystem. This is since all species interact and affect each other. In this case they are always competing in such a way that leads to the development of the ecosystem. Page 55 emphasises “If extinction was driven by natural selection and natural selection only by natural selection, the two processes had to produce roughly at the same rate” This goes to show that through natural selection there is an interconnectedness in the ecosystem because the development of a species affects the survival of another.