7 Billion Humans | National Geographic Magazine: Crowds on the Streets of Calcutta | India

Previous Image

Crowds on the streets of Calcutta | Bengal State, India

At the birth of Jesus, the global population was an estimated 200 million. (It was probably easier then than now for the meek to inherit the Earth.) It took until the early 1800s to reach one billion. We went from six billion to seven in a veritable blink of the eye: 12 years.

In 1950, for each person 65 and older, there were more than six children under 15. By 2070, elderly people will outnumber children under 15.

—Joel E. Cohen,  author of “How Many People Can the Earth Support?”