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.