In these works, he provided biological and geographical explanations for the question why Europeans were able to succeed with relative ease in what he referred to as the Neo-Europes of Australasia, North America, and southern South America.
Dalam buku-bukunya, ia memberi penjelasan dari sudut pandang biologi dan geografi tentang sebab bangsa Eropa berhasil berkembang di Neo-Eropa yang mencakup Australasia, Amerika Utara, dan Amerika Selatan selatan.