demographic transition

On the 31st of October we will officially reach 7 billion people on the earth. Over the next week or two we'll be talking a lot about population issues, and I wanted to start by doing a light revision of an article I wrote some years ago about a concept a lot of people don't grasp very well - the idea of demographic transition and what it means. The term "Demographic Transition" describes the movement of human populations from higher initial birth rates to a stabilzed lower one, and seems to be a general feature of most societies over the last several hundred years. Initially, birth rates…
There's a great scene in the book _Cheaper By the Dozen_ (which had almost nothing to do with the recent movie Steve Martin was in, although there's a fairly good old one) in which Lillian Moller Gilbraith, mother of 12 (11 surviving) is offered by a joking friend as the ideal host for a Planned Parenthood organizational meeting. The PP representative, who has been told that Gilbraith is a model organizer, a professional woman and a leader in her community - but not that she has 11 kids. "Within 15 Miles of Organizational Headquarters!" announces the representative of Planned Parenthood in…