对于大多数现代社会而言，相对便宜的公共医疗预防措施，例如提供清洁饮水和固定的疫苗是推进寿命预期的主要因素。
For most of modern history, relatively inexpensive public health precautions, such as providing clean drinking water and routine vaccinations, have been the main factor pushing up life expectancy.