People under the age of 25 make up 43 % of the world 's population , the United Nations says . NEW : World population could surpass 2 billion by the end of the century , the U.N. says . In 2010 , the world 's population was 2 billion . People under age 65 make up 80 % of the current population . Africa 's population is expected to more than triple this century .
NEW : World population could surpass 2 billion by the end of the century , the U.N. says . In 2010 , the world 's population was 2 billion . People under age 65 make up 80 % of the current population . Africa 's population is expected to more than triple this century .