ABSTRACT
Perhaps the greatest of all human achievements has been the enormous increase of human longevity that has occurred over the past few centuries. The average length of life in the early history of our species was probably in the range of 20 to 35 years (Table 1). By 1900, this value had already risen to around 45 to 50 years in industrialized countries. Slightly more than a century later, the world’s healthiest countries now have a life expectancy at birth of around 80 years. Thus, roughly half of the historical increase in human life expectancy occurred during the twentieth century. Of course, much of the increase in this average value has been due to the near elimination of infant and childhood deaths. According to the available evidence, in the distant past, around a quarter of all babies died in their first year of life. Today, in the most advantaged countries, less than a half percent of infants meet a similar fate.
