At the beginning of human history, God gave mankind a mandate to “Be fruitful and increase in number; fill the earth” (Genesis 1:28). Sometime later—around the 19th-century—people started wondering, “Is the earth close to being filled with humans?”
In 1798, Thomas Malthus predicted that if current birth rates persisted, many in Great Britain would starve to death. Instead, the birth rate was matched by increased agricultural yields, allowing more people to be fed with fewer land resources.
Despite Malthus’s failed predictions, others worried that population would eventually outgrow our resources. In 1838, the Belgian mathematician Pierre Verhulst calculated that his country could never support more than 9.4 million people. Verhulst was wrong; Belgian’s current population is more than 11 million.
In 1925, Raymond Pearl, head statistician for the U.S. Food Administration during World War I, calculated the maximum population limit of the U.S. to be 200 million. We reached that in 1968 and are currently at around 319 million. Pearl also predicted the world population limit would be 2 billion, a number that was surpassed in 1930.