by caroline duffield bbc news , niger delta monday , 5 october 2009 https : //youtube.com/watch ? v=6nxnxtniwkc http : //fournonblondes.com/ chapter 13. http : //prb.org/articles/2002/howmanypeoplehaveeverlivedonearth.aspx for `` how many people have ever lived on earth '' by carl haub , chair of population information at the population reference bureau .