Kolbert provides multiple examples supported by historical standards and scientific evidence that the Sixth Extinction has been solely caused by human beings and human activities. She correlates the spread of Homo sapiens throughout the world with the displacement and eventual extinction of multiple species. Further proof is provided by humans’ tendency to “overkill” and destroy species, as well as to eradicate animals through activities such as pollution, overfishing, mining, and deforestation.

A theme throughout the text is catastrophism, a scientific theory first proposed by Cuvier, and thoroughly rejected by his peers. Further scientific research combined with a paradigm shift in thinking has brought far more credence to the idea that catastrophes and cataclysmic events have had an impact on the emergence and extinction of individual species. While scientists believe in smaller catastrophes, more studies now show the evidence of Five Extinctions occurring at different points in time that are linked to catastrophic events, such as meteor strikes. The role that catastrophism plays in the Sixth Extinction remains to be entirely seen.

Kolbert is quite frank about the effects that climate change, and specifically global warming, have had on the Earth and its species, particularly during the