Expansion of the Human System began with divergence and migration of speaking communities in their homeland. Then, up to 45,000 years ago, migrants moved southwest across Africa and eastward along the Indian Ocean littoral, as documented through archaeology, genomics, and climate. Language evidence, supplemented by an accompanying website, confirms the value of Joseph H. Greenberg’s tradition of large-scale linguistic analysis. African migration included multiple settlements among preexisting hominin populations. The parallel migration into Asia, now identified genetically as a single migration, relied on watercraft at most stages. Surviving language groups indicate the path of migrants along the Indian Ocean littoral. Only after 45,000 years ago were migrants able to move northward, into the ecologically distinctive temperate zone. Once in the steppes, migrants moved east to Northeast Asia and west to the Black Sea. As networks facilitated exchange of dogs, religious ideas, bows and arrows, the Human System thus expanded from its initial locality to become a hemispheric network of communities in contact.

After millennia of cooling, the Last Glacial Maximum reached an extreme. Every species adjusted, even in the tropics. Humans responded with new social organization: communities pooled resources to face issues of leadership, forming confederations that pooled resources. After the coldest moment – 21,500 years ago – migrants moved to newly fertile lands as temperature rose almost ceaselessly for millennia. Intensive food gathering was accompanied by productive institutions: architecture for permanent homes, textiles, ceramics, and workshops for visual representation. Eurasiatic-speakers moved westward across Siberia; others moved both north and south in eastern Asia and between Africa and western Asia. New details on American settlement now reveal two groups of Asian voyagers who followed the “kelp highway” just offshore. The main group formed settlements along the Pacific littoral, expanding inland from points as far as southern Chile by 19,000 years ago. By the end of the Pleistocene, the achievements of early humanity included occupying most of Earth, supplementing foraging with production, exquisite visual representations, and dependable adaptability.