'No large group is known to have maintained complete reproductive isolation for extended periods…
no matter the languages we speak or the colour of our skin, we share ancestors who planted rice on the banks of the Yangtze,
who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and
who laboured to build the Great Pyramid of Khufu.'
—Douglas Rohde, Steve Olsen & Joseph Chang, Modelling the recent common ancestry of all living humans,
in Nature (2004)
Population of the world and continental regions,
young adults (aged 15-34 years): 1950-2010
Notes: Of the world's 2.17 billion young adults in 2005, 1.35 billion lived in Asia, 320 million in Africa,
210 million in Europe, 190 million in Latin America and the Caribbean, 90 million in Northern America, and 10 million in
Oceania.
Notes: Of the world's 2.17 billion young adults in 2005, 1.35 billion lived in Asia, 320 million in Africa, 210 million in Europe, 190 million in Latin America and the Caribbean, 90 million in Northern America, and 10 million in Oceania.
Source of data: United Nations Population Division, "World Population Prospects: The 2006 Revision".