Not just men in fact but women as well. The question has been one that I’ve been throwing back and forth for a while now. I’ve encountered similar questions before all essentially asking “how many people does it take to sustain a technologically developed society?” The question implies a society that we in Britain are used to with as much consumerism, technology, law and light bulbs as we have today. The answer might be a little more than most would guess.
Throughout history we have gone forth and multiplied. Countless times wooden boats have been built carrying less people than the average train on the Tube across waters to new lands where those people have managed to build a society. From that we would think that the answer to “how many people does it take to sustain a technologically developed society?” wouldn’t be that much. Perhaps the citizens of our hypothetical society can each be employed only in jobs that are necessary with no overlap or needless jobs (by needless jobs I refer to multiple companies providing the same service which in our hypothetical society can be cut down). In colonial times they would start essentially from scratch and work their way back up with trade and supply from neighbouring lands boosting the fledgling society. But in trying to answer “how many men…” we need to come to a number of how many people we need to maintain the world we are used to rather than rebuild it.
Pre-1900 most things could be constructed by generalist industries (blacksmiths, carpenters, masons etc). Over the past century however our world has exploded into an ecology of superspecialisms. Whilst early machines could be built or maintained by the typical tinkerer in his workshop the complexity of everyday objects today has pushed the reality of one dedicated jack-of-all-trades up to a large interdependent group of masters in one field.
A few examples; today’s smartphones contain microprocessors built from transistors just tens of nanometres thick, wires etched a few dozen atoms wide, GPS systems, radio transmitters, microscopic pressure sensors underneath a full colour screen all packaged in a palm sized container. In the medical field rather than having the traditional doctor, surgeon, nurse, dentist we have specialists in far narrower fields like cardiologists, radiologists, neurologists, ophthalmologists etcetera etcetera. Examples like this can be seen in all walks of life and in building our hypothetical society we can forget none of them! A temporal lobe neurosurgeon might seem unnecessarily specialised until you get a tumour that needs to be excised. And for each field we must have a sizable portion educating the next generation. Contrary to Heinlein’s popular quote specialisation is not just for insects.
So to address the original question, how many men does it take to make a light bulb? Let’s break it down; a typical incandescent light bulb is made up from a glass bulb containing a tungsten filament surrounded by an inert gas. Sounds simple at first but for all of that we need an industry to mine and refine the materials, transport to take those materials to factories (and consequently an industry to maintain that infrastructure), make the bulbs and ship them out to the people. Apply that to every product we have and how many industries do we need now? Sure there may be no overlap in some areas (we may only need one tungsten mine and one infrastructure maintenance consortium) but the sheer complexity of life in the developed world today is mind boggling.
Adding together the populations of large hives of industry such as NAFTA, the EU and China we come to a number of over two billion. This number can be trimmed to about one billion by taking into consideration the communities that provide little overall input (half of China’s population is solely agrarian for example). If we take one billion people to be the upper bound we can consider removing as much overlap as possible whilst maximising efficiency but I see no reason as to why the lower bound number would not be less than the high tens or low hundreds of millions. So to live in a society capable of providing all the technologies and services we are used to would require a population greater than that of the United Kingdom today.
This realisation has important implications. For those of an ideology that the world would be a better place with less people simply living in one with nature or those who have a special place in their heart for the idea of living on Mars (or any other non-Earth body) the reality is quite different. To maintain a technologically developed society such as ours we are not going to be living in self sufficient pioneering communities, instead we have to be a thriving interdependent hive of industries, experts and above all specialists.