Life Expectancy and Income among the First Countries to Begin Health Transitions

Within the last two centuries every country around the globe has experienced sustained periods of progress in survival, with health transitions beginning as early as the 1770s and as recently as the 1970s.1 Around 1800, when some countries were beginning their transitions, life expectancy at birth was as low as 22.5 years in the indigenous populations of Oceania and as high as 34.8 years in some parts of the Americas. The global average was about 28.5 years. (Life expectancy at birth measures the current probability of surviving at each age for the year in question, rather than the actual survival prospects of a person born that year. Thus it gives the best assessment available of population survival that year.) Working with countries of the world as they were identified in 2000 rather than with the much more ambiguous boundaries and identities of 1800, and considering survival in the decades just before each country began its health transition, the lowest pre-transition life expectancy was perhaps 20.1 years (Pakistan) and the highest 40 to 42 years (Scotland, Switzerland, the United States).2 The overall average across countries in the periods when they began health transitions was 33.1 years.3 Both that and the 1800 average were higher than the life expectancy of 20–25 years at the transition from Paleolithic to Neolithic populations, around the domestication of plants and animals, but only by a few years.4 Thus, a true revolution in survival has occurred since 1800, with most of the gains having come since 1920. Such estimates of life expectancy average across long periods for pre-