With regards of population, if I might pose a personal theory, that is it grew firstly by way of people moving from the open country to the towns and cities. Society encouraged promiscuity, without means of contraceptive. Then when contraceptives where made available and encouraged, society and culture still encouraged around three children per woman; by which time more people had been encouraged to register and for voting in what had become a democracy. So, I theorise that population has been seen to grow in the towns and cities, by those means. This does not mean that I believe the global population has grown, to an alarming amount, or that people in polluted towns and cities, with all their vises, do live longer; or, that tribes in the wilderness have more than two children per woman on average and that they all live longer.
