At our November gathering, the group decided this month’s topic is on longevity – something near to each of us, especially as we become more aware of the countdown to our final years.

As I thought how to frame the discussion and readings, what kept coming to mind is a statistic I read many years ago: In 1900, the average life expectancy for a white U.S. male was 47 years (sadly, 33 years for a black male). By the year 2000 those figures increased to 75 and 68, respectively. Here’s a chart that shows this year-by-year for both males and females. That said, today several countries (notably in Africa) still have life expectancies in the 30-to-early 40-year range.

How did that happen? Did a bunch of incremental changes kick in year after year to ratchet up the figure? Was there some set of trigger events – obvious ones such as clean water, diet, immunizations, or perhaps ones less clear (but potentially just as powerful) such as the impact of tightly-knit communities?

Here are starter links for our upcoming discussion …