… as long as they are healthy, well fed and well educated
Much of the panic about falling birth rates can be dispelled once we realise that (barring catastrophe) there will almost certainly be more people alive in 2100 than there were in 2000. But what about the distant future? Dean Spears, co-author of After the Spike has kindly provided me with projections showing that with likely declines in fertility the world population will decline by half each century after 2100, reaching one billion around 2400. Would that be too few to sustain a modern civilisation ?
We can answer this pretty easily from past experience. In the second half of 20th century, the modern economy consisted of the member countries of the Organization For Economic Co-Operation and Development (OECD). Originally including the countries of Western Europe and North America, and soon extended to include Australia and Japan, the OECD countries were responsible for the great majority of the global industrial economy, including manufacturing, modern services, and technological innovation.
Except for some purchases of raw materials from the “Global South”, produced by a relatively small part of the labour force, the OECD, taken as a whole, was self-sufficient in nearly everything required for a modern economy. So, the population of the OECD in the second half of last century provides an upper bound to the number of humans needed to sustain such an economy. That number did not reach one billion until 1980.