Transportation tech, war, famine, climate change, poverty, industrialization, and urban growth these development facilitated the vast circulation of people in the early twentieth century.
Population growth is a period of extraordinarily rapid human population growth in the twentieth century that quadrupled human numbers in less than a century. Primarily gained in the Global South. Lower death rates and infant mortality due to new medical tech and public health reforms.
Population growth was sustained by Green Revolution (Innovations in agriculture during the twentieth century, such as mechanical harvesters, chemical fertilizers, and the development of high-yielding crops, that enabled global food production to keep up with, and even exceed, growing human numbers.
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