My blog of 21 June 2011 was entitled:   A WORLD POPULATION OF 7 BILLION .  I went on to say: If there has been any criticism of my books, it is that  I have ignored the most important parameter:  the world population .   I didn't have a full chapter dedicated to this topic in any of my publications, and not one of my 100+ Huffington Post articles treated this subject. Why? ... mostly because there was not much I could add to the subject than to say that population growth will reverse once the world becomes economically prosperous, for then, the central government will have something like Social Security in place and parents won't need to have many children to take care of them at old age . It took us from our beginnings in Africa, perhaps 300,000 years ago, to finally reach a population of 1 billion in 1804.  218 years later, we last year reached 8 billion.  However, the  good news is that the time it takes to double our population is finally increasing . What about the future?