Surprising no one mentioned sanitation, which was my first choice.
Before the invention of the toilet and sewer systems, mankind lived essentially in filth, dying young of disease and other good stuff. All the later inventions couldn't be possible if people were dying in their early 30s.
All this filth definitely made sex less enjoyable or downright disgusting, so global population increases for all of humanity up to that point was stagnant. Only sanitation and the industrial revolution did we see explosive growth in population and technology.
Before the invention of the toilet and sewer systems, mankind lived essentially in filth, dying young of disease and other good stuff. All the later inventions couldn't be possible if people were dying in their early 30s.
All this filth definitely made sex less enjoyable or downright disgusting, so global population increases for all of humanity up to that point was stagnant. Only sanitation and the industrial revolution did we see explosive growth in population and technology.