In a previous post, Dr. Millard made the excellent point that : "The average lifespan will not be particularly informative. What is needed is information on the age structure of the populations. To take an exaggerated, (and hypothetical) example: a population with average lifespan 30 years could have: (a) 50% dying age 1 and 50% dying age 59, or (b) 50% dying age 29, 50% dying age 31. The former population will have a higher incidence of age-related diseases like cancer, heart disease, and arthritis. Diseases of extreme old age (e.g. Paget's disease which is unknown under 50 years of age, and reaches prevalences of 10-15% in Caucasians over 90 [1]) are seen in archaeological populations with average age of death of 30 years or so, because there were many individuals who died young, but also some who reached old age. The average age of the living, rather than the dead, might be more informative, but still not as good as the age structure of the living population." In this regard, there has only been a single study published showing the life table of hunter gathers (1). The following Table ( I hope it comes throught in a proper order) was constructed using data from a large sample of Yanomama males. Column A is the mortality schedule (the chance that those who reach the age class will die before reaching the next age class. Column B is the chance of surviving the age class or 1-A. Column C is the number of survivors left at the beginning of the age class out of every 100 born. Here we go: Age A B C 0 .26 .73 100 1 .16 .84 73 5 .11 .89 62 10 .08 .91 55 15 .14 .86 50 20 .15 .85 43 25 .16 .84 36 30 .16 .84 30 35 .16 .84 26 40 .16 .84 21 45 .17 .83 18 50 .17 .82 15 55 .21 .79 12 60 .28 .72 10 65 .36 .64 7 70 .47 .53 4 75 .61 .39 2 80+ 1.0 0.00 1 Thus, as Dr. Millard has pointed out, the age structure of the entire population tells us more about mortality than a simple average life span. In the Yanomama, the constant warfare that goes on takes a high toll of young adults and adults - also notice the high infant mortality rates (27%). Still a considerable percentage of the population lives beyond age 50. Data for women is found in reference (1) for interested readers. REFERENCE 1. Neel JV. Health and disease in unacculturated Amerindian populations. Ciba Foundation Symposium 1977;49:155-77.