(Four decades later, he recalled these impressions in The Descent of Man to support his argument that just as humans had descended from "a lower form", civilised society had arisen by graduations from a more primitive state.
Catro décadas despois, el lembraba estas impresións en The Descent of Man para apoiar o seu argumento de que os humanos desdendían dunha "forma inferior", e a sociedade civilizada orixinárase gradualmente desde un estado primitivo.