Chapters 10-11 Summary

Darwin believed that species were limited by geographical barriers. He did not understand why similar fossils would sometimes appear on multiple continents. Eventually, scientists developed the theory of Pangaea, a supercontinent “when all the land on Earth was part of a single expanse.” Humans have effectively reconnected the continents as they move species across oceans and large land masses, thus creating a “New Pangaea.”

Invasive species—nonnative species that disrupt the ecosystems they colonize—can be catastrophic. Sometimes, to counteract invasive species, humans have introduced more invasive species.

Earth was once home to megafauna (animals of large size), and most scientists blame humans for their extinction. Before humans, large mammals had few predators. Nearly all large mammal species are now endangered or extinct.

Chapters 10-11 Analysis

Kolbert’s analysis of Darwin’s lack of understanding of species transience again supports her idea that scientific processes and thought continue to evolve. Implicit in this idea is the idea that there is still much to learn about both the history and the future of ecology.

In Chapter 10, Kolbert introduces invasive species as a new way in which humans have impacted biodiversity. Whether intentionally or inadvertently, humans have spread plants, animals and even pathogens across the planet. In doing so, they have caused serious issues.

Invasive species and pathogens often have the upper hand against native species, with few predators or competitors in a new environment. The idea that people are creating a New Pangaea shows the magnitude of the changes humans have brought upon the planet. What took millions of years to form is being undone in a matter of generations.

In Chapter 11, Kolbert develops the main idea of human impact by suggesting that the presence of the earliest humans correlates with the extinction of giant mammals. If this theory is right—and science suggests it is—the implication is that humans are destructive by nature. While Kolbert has not been shy about her theory that humans are causing the Sixth Extinction, this development brings readers back to Chapter 6, in which she refers to the human race as an “overkiller.” If this is the case, there seems to be little hope for the future.