This chapter explores the reasons why Africa became the cradle of humankind and analyzes the influence of natural factors on the early evolution of hominins. It was in Africa that a particular combination of factors, including landscape diversity, climatic variability, and abundance of resources, created the necessary conditions for the evolution of large social apes. Smaller apes live in almost all places with tropical climates, and gibbons and orangutans in southern and southeastern Asia do not live in groups. For specific reasons, other large social primates (gorillas, chimpanzees, bonobos, baboons), which have significantly advanced in cognitive development, did not follow a similar evolutionary path as hominins. The alternation of ice ages and interglacials caused alternating dry and wet periods in the African climate of the Pleistocene. The author considers modern short and long turnover pulse hypotheses, according to which climatic changes stimulated speciation and migration. Hominins experienced dramatic periods of depopulation and demographic growth. The dynamics of the African multiregional hominin metapopulation included forced migrations, intergroup competition, extinction of some forms and emergence of new ones. The rift lakes of East Africa, with their rapid cycles of filling and drying, had a major impact on these evolutionary dynamics. These “ephemeral” lakes created a particularly dynamic habitat that stimulated the development of hominin adaptations and thus contributed to increased brain volume. The chapter also discusses the conditions that caused H. erectus to migrate out of Africa. The peculiarities of the African climate affected not only hominins but also other large social mammals. The author formulates a number of general hypotheses about the role of natural factors in vertebrate evolution. He also proposes a new formulation of the “geographic factor” that takes into account not so much the static characteristics of habitat as its variability.