Limon Miah- Chapter 4 Journal

In chapter 4 of, The Sixth Extinction, Kolbert discusses how a scientist named Walter Alvarez discovered traces of an asteroid that hit the Earth  during the Cretaceous period which had ended up killing the dinosaurs and the other species of animals on Earth during the time. At first scientist rejected the Alvarez theory as they believed that the mass extinction isn't a possibility and instead argued that the lost species were a result of slow and gradual extinction. However, as evidence continued to mount in support of the Alvarez theory, such as discoveries of shocked quartz, and a crater found in Mexico which had remnants of melted rock from the Cretaceous period. This all strengthened Alvarez’s argument that there was indeed an asteroid that hit the Earth and that the dust that it put in the Earth's atmosphere is what would wipe out the species. Furthermore later in the chapter, Kolbert talks about her visits with Neil Landman, a specialist in ammonites. Kolbert writes about ammonites in this chapter to show that though the asteroid hit during the Cretaceous period wiped out the ammonites species, as they bred small weak ammonites, while on other hand, Nautilus, a species similar to ammonites, were able to survive as they laid eggs that were able to survive changes in temperature and water pressure. This brings up Kolbert's argument on how the modern species on Earth originated from the species from the Cretaceous period that managed to survive, but also that the survival of a species in the case of a mass extinction depends on their qualities.

I made a connection with the previous chapters discussion on Darwin's theory to chapter 4. Darwin's theory stated that the species with dominant characteristics will be able to ensure their survival while others lacking them will die out. This is the same situation in the case of the Ammonites and nautilus, as only one species was able to make it past the asteroid hit, and it was the nautilus due to their abilities to withstand the changing environments of Earth, while the Ammonites were not able to due to their inability to continue as the versatile, strong spiral-shelled animals that they once were. Additionally, this chapter connects to the APES theme that science is a process and it constantly changes the way we think about the world. For example, in the chapter, the Alvarez theory was disagreed with as the majority of scientist strongly believed that extinction was nothing more but a slow and gradual process, and that a mass extinction was simply unreasonable. However, as we now know, a mass extinction is more than possible, as all new evidence supports the Alvarez theory. In the text it states, “Here you have a challenge to the uniformitarian view point that basically every geologist and paleontologist had been trained in… and what you saw was people looking at the evidence and they gradually did come to change their minds” (pg. 82). Essentially, the message behind this quote is that science isn't necessarily a set answer to one of history's mysteries, rather instead it is an idea of what happened and with evidence it can be used to change the minds of what individuals may deem to be true. It took eleven years for the Alvarez theory to be taken seriously by the scientists in the world, but however eventually it was able to succeed and prove to be the most reasonable explanation for the extinction of so many species in the world.