The Last Taboo — There are 7 billion humans on earth, so why can't we talk about population?

IT'S MIDNIGHT on the streets of Calcutta. Old women cook over open fires on the sidewalks. Men wait in line at municipal hand pumps to lather skin, hair, and lungis (skirts), bathing without undressing. Girls sit in the open beds of bicycle-powered trucks, braiding their hair. The monsoon's not yet over, and grandfathers under umbrellas squat on their heels, arguing over card games, while mothers hold bare-bottomed toddlers over open latrines. On every other block, shops the size of broom closets are still open, kerosene lights blazing, their proprietors seated cross-legged on tiny shelves built above their wares of plastic buckets or machetes or radios. Many people sleep through the lively darkness, draped over sacks of rice or on work carts full of paper or rags or hay. Groups of men and women, far from their home villages, sprawl haphazardly across the sidewalks, snoring.

World population to surpass 7 billion in 2011

Global population is expected to hit 7 billion later this year, up from 6 billion in 1999. Between now and 2050, an estimated 2.3 billion more people will be added—nearly as many as inhabited the planet as recently as 1950. New estimates from the Population Division of the Department of Economic and Social Affairs of the United Nations also project that the population will reach 10.1 billion in 2100.

These sizable increases represent an unprecedented global demographic upheaval, according to David Bloom, Clarence James Gamble Professor of Economics and Demography at the Harvard School of Public Health, in a review article published July 29, 2011 in Science.

Over the next forty years, nearly all (97%) of the 2.3 billion projected increase will be in the less developed regions, with nearly half (49%) in Africa. By contrast, the populations of more developed countries will remain flat, but will age, with fewer working-age adults to support retirees living on social pensions.