No reliable studies exist from centuries past, but best guesses mark the start of the 19th century as the one-billion world population milestone. That means in just two centuries the number of human beings on the planet went up sixfold. The population curve has grown progressively more vertical: 120 years to reach two billion, 33 years to three billion, and thereafter a billion was added roughly every decade and a half. Just before the turn of the millenium the world celebrated another population milestone, the six million mark.

On this day, October 12, in 1999, by United Nations projections the six billionth baby was born somewhere in the world.

Statistically, the baby was most likely to be Asian. Population growth has not been the same everywhere: Europe and the American continents have seen relatively flat growth, while Africa has seen a dramatic rise in population due in part to improved medicine and public health measures. The Asian continent is far and away the leader in population and population growth rates. But the symbolic six billionth baby chosen by the U.N. was actually born in the Balkans. Adnan Mević, of Sarajevo, in Bosnia-Herzegovina, was born two minutes after midnight on the designated day.