180 Superlongevity Without Overpopulation A  reading  of  economic  and  social  history  quickly  makes one  thing  plain:  throughout  history  people  have  envisaged overpopulation.  Even  the  great  nineteenth  century  social scientist W. Stanley Jevons in 1865 claimed that England’s industrial  expansion  would  soon  cease  due  to  the  exhaus- tion of the country’s coal supply. [15] However, as shortages developed, prices rose. The profit motive stimulated entre- preneurs to find new sources, to develop better technology for finding and extracting coal, and to transport it to where it was needed. The crisis never happened. Today, the USA has proven reserves sufficient to last hundreds or thousands of years. [16] If one resource does begin to run low, rising prices will encourage a switch to alternatives. Even a vastly bloated population cannot hope to exhaust energy supplies. (Solar energy and power from nuclear fission and soon fusion are practically endless.) So long as we have plentiful energy we can produce substitute resources and even generate more of existing resources, including food. Even if population were to grow far outside today’s highest projections, we can expect human intelligence and technology to comfortably handle the numbers. Human intelligence, new technology, and a market econ- omy will allow this planet to support many times the current population of 6.2 billion – it can support many more humans than we are likely to see, given trends toward lower birth rates. Many countries, including the USA, have a rather low popu- lation density. If the USA’s population were as dense as Japan – hardly a crowded place overall – our population would be 3.5 billion rather than 265 million. If the USA had a popula- tion density equal to that of Singapore, we would find almost 35 billion people here, or almost seven times the current world population.  New  technologies,  from  simple  improvements in  irrigation  and  management  to  current  breakthroughs  in genetic engineering should continue to improve world food