Read the following quote and decide what year it was written:"In our own time the whole of [our nation] has been subject to a low birth rate and a general decrease of the population, owing to which cities have become deserted and the land has ceased to yield fruit, although there have neither been continuous wars or epidemics....For as men had fallen into such a state of pretentiousness, avarice, and indolence that they did not wish to marry, or if they married to rear the children born to them, or at most as a rule but one or two of them, so as to leave these in affluence and bring them up to waste their substance, the evil rapidly and insensibly grew."
Would it surprise you to learn this was written by Polybius, a Greek historian about 150 BC? When a culture decides to stop having children, they die out, literally. The total fertility rate of a population is the average number of children that would be born to a woman over her lifetime. In order for a population to replace itself, the total fertility rate must be slightly higher than 2.1 births per woman over the course of her lifetime. If Sam and Jenny get together and have two children, they have in essence only replaced themselves in the world. If they had three children, they contributed +1 to the world population. The replacement rate is above 2.0 due to such factors as childhood mortality and mortality in the female population before the end of childbearing years.Developed countries tend to have a much lower fertility rate than less developed nations. Click here to see fertility rates by nation. It seems that affluence kills societies due to a number of factors. As countries become more developed, the cost of living increases, making child rearing an expensive proposition. This leads to what is called the demographic-economic paradox. Developed countries have more wealth, and would logically suggest they would be able to have more children. Yet this never happens, in fact the more affluent societies around the world become, the less children they have. As socialism creeps further and further into developed nations, radical changes will occur in the near future. Secular societies with socialized economic models are built upon the high birth rates found in religious beliefs. In other words by promoting an increased secular, affluent, and selfish ideology, the secular state will always kill itself. People stop having children, and then there is no one left to pay for fat government pensions. Look at the fertility rate of the European Union, 1.50! Remember your population shrinks if you fall below 2.1 births per woman.
This topic is discussed extensively in a book written by Mark Steyn called America Alone. It will change the way you look at demographics.