Mortal Demographics

I learned a fascinating concept on aging and death this week based on some vital statistics data.  I begin with a plot:


This is the plot of rate of deaths in the U.S. for different ages and across 40 years.  Note the bimodal age distribution of death.  The first year of life is fraught with risk and then mortality rates drops until teenage years with an increase especially among males: this is an age of increased accidental and violent injuries.  After plateauing in the 20's, the death rates after 30 years of age begin climbing exponentially.   As this is plotted on a logarithmic scale it appears as a line.  The amazing aspect to this linear feature is that the slope of death is largely preserved.  This slope exists not only in the U.S. but the same relationship has been studied and observed in other nations.  Researchers have also looked at other animal species and found a similar slope of mortality.

What has changed to this linear feature in the last 4 decades is a gradual lowering (darkening paths) of its "intercept" and one could argue and presume from the graph that this is due to improved care in childhood over the last four decades.  This also speaks to the Barker hypothesis regarding how determinants of chronic diseases can begin very early in life.

Note, these concepts are not original but I am delighted by how the graph came out to illustrate them.