Diet and caloric intake, along with epidemic disease, famine, war, and other disasters, kept human life expectancy much shorter than it is today. In many of the richest and most advanced parts of the premodern world, from China and Japan in East Asia to England and Germany in Europe, life expectancies at birth were thirty to forty years,23 or half of what they are today for most of the developed world
In the premodern world, people didn’t live as long because of poor diets, disease, famine, and war. Even in rich countries, most people only lived about thirty to forty years, which is much shorter than today.