Just do the math

Just to bring in another way to look at this, I will provide an example. Let us assume that there is a country with 1000 people total, with 300 of them divided equally between single females and single males within the age of childbearing but not having any children, this is 150 females and 150 males. If these 300 individuals were to become couples at the same instant and would become immediately fertile, contributing one child to the country´s population each couple, everything else remains the same, after nine months the country would have increased to a population of 1150. Straight forward. Let us further assume that births were equally divided between girls and boys, so that in the future these contemporary individuals will come to the age were their parents were at the time this example began. Seventy five women and men within childbearing age would contribute 75 new individuals to the total population of the country bringing the new total to 1225 under a similar scenario. The relative rate of growth in the country´s population from the first event to the second would show a sharp decline, but nevertheless the population went up. Over the time that went by, no one died, (after all it is just an example of my view). If we continue with the example replicating the same scenario over time with a continuing decline in birth rates and no one dying, it will reach a point where there will be no more new additions to the population because the childbearing possibilities have been exhausted with ever decreasing childbearing couples as the scenarios take place in time. My point is that in order to have a sustainable society, it must be capable to attain the capability to have a replacement rate that makes it viable and avoids it extinction. Of course there are instances where this is not happening but, in a recent trip a made to Europe, it was obvious that in the near future Europe will be facing a diluted version of what I described in my example. Many European countries have birth rates that have fallen below what makes their societies viable and are faced with the dilemma of having to support an ever increasing elderly population with fewer individuals as a result of not having had enough children. What follows I took from Wikipedia. With 82 million inhabitants in January 2010, Germany is the most populous country in the European Union. However, its fertility rate of 1.42 children per mother is one of the lowest in the world, and the federal statistics office estimates the population will shrink to between 65 and 70 million by 2060. Italy will need to raise its retirement age to 77 or admit 2.2 million immigrants annually to maintain its worker to retiree ratio. About 25% of Italian women do not have children while another 25% only have one child. The region of Liguria in northwestern Italy now has the highest ratio of elderly to youth in the world. Ten percent of Liguria's schools closed in the first decade of the 21st century. The city of Genoa, one of Italy's largest and the capital of Liguria, is declining faster than most European cities with a death rate of 13.7 deaths per 1,000 people, almost twice the birth rate, 7.7 births per 1,000 people, as of 2005.