overpopulation

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…they have ever since human beings began living in large groups. Technological upheaval and change will be the rule rather than the exception. But provided that democracy and freedom continue to spread around the globe, albeit at a sometimes incredibly slow pace, we should expect the 21st century to be a much better place to live to the same degree that the 20th century has been immeasurably better for humans than the 19th century was.