(Courtesy Patrick Gerland *06)
Earlier this week, according to United Nations demographers, the world’s population reached an estimated 7 billion people – a figure that drew significant attention from the media both as a current event and a milepost in the larger trend of global population growth.
Behind the scenes, Patrick Gerland *06 played a significant role in the work that led to the UN’s estimate. Gerland, a native of France, received his Ph.D. in population studies from Princeton before joining the demographic estimates and projections section of the UN Population Division.
Princeton has a long history in international demography, Gerland notes, including the influential work of Frank W. Notestein, who created the University’s Office of Population Research in the 1930s and later served as the founding director of the UN Population Division.
At the UN, Gerland specializes in demography for Africa and Asia, two regions in which population counts can be difficult to assess, due to incomplete birth and death records. “The information that exists is often very limited,” he explains. “You depend primarily on surveys and censuses to give you snapshots.” Demographers do their best to fill in the blanks and sort through contradictory information, using a “mixture of detective work and statistical modeling,” he says.
In addition to making current estimates, demographers explore “what if” scenarios, aiding other UN groups that explore policy issues in everything from energy use to education. But the field’s popular appeal seems to spike when national or global populations reach milestones.
“People are human,” Gerland says. “They like round numbers.”

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