As we are all aware, life expectancy has increased globally over the last few hundred years in dramatic fashion. Improvements in water, sanitation, medical technology, food distribution and wealth, among others, have increased the average life expectancy at birth in the U.S. from 47 in 1900 to about 80 years old today.
However, in terms of the maximum life span that humans can live, there has been relative less change over the ages and no real increase since the 1970s. A few hundred years ago the very oldest people lived to about 100 and a bit. Today, our very old people can live to about one hundred and a bit more. Medical advancements now allow more people to live to 100ish, but our ability to extend life past that age has hardly budged.
The average survivorship of species is commonly plotted on what is called a “survivorship curve.” Homo Sapiens fall into a Type I curve. Birds are a good example of Type II and most plants and many reptiles fall into Type III.
Basically, advancements have helped humans change the shape of the curve – make it more Type I-shaped and less Type II-shaped.
Similarly, here’s a chart of survivorship curves over time for women in Japan:
A striking result of the apparent limit to human lifespan is that cures for various diseases likely do not greatly increase life expectancy. The below table is from the book Scale based on data from the World Health Organization and shows the projected average increase in life expectancy for each category of disease that is cured:
|CATEGORY OF DEATH||POTENTIAL GAIN IN LIFE EXPECTANCY|
|Cardiovascular Diseases||6.73 Years|
|Respiratory diseases||0.97 Years|
|Health-care accidents||0.92 Years|
|Digestive System diseases||0.46 Years|
|Infectious and Parasitic Diseases||0.45 Years|
|Firearm deaths||0.40 Years|
“Even if every cause of death were eliminated, all human beings are destined to die before they reach 125 years old, and the vast majority of us will do so well before we reach that ripe old age.”
-From Scale by Geoffrey West
Maybe we’ve reached peak life span????
A study published in Nature in 2016 by researchers at the Albert Einstein School of Medicine conclude that maximum human lifespan has a ceiling and that we’ve basically reached it. They put the average ceiling at 115 years of age with a few outlier record-setters living longer. Note that record for the world’s oldest person is 122 years of age.
Quote by a co-author the Nature study:
“Further progress against infectious and chronic diseases may continue boosting average life expectancy, but not maximum lifespan. While it’s conceivable that therapeutic breakthroughs might extend human longevity beyond the limits we’ve calculated, such advances would need to overwhelm the many genetic variants that appear to collectively determine the human lifespan. Perhaps resources now being spent to increase lifespan should instead go to lengthening healthspan — the duration of old age spent in good health.”Source
The idea of increasing healthspan is a good one. In the U.S. the average age lived in “good health” is 68.5 years. While the U.S. has a longer life expectancy than China, we have a slightly shorter “healthy life expectancy.” Check out this chart:
A few related IFODs:
What Would Have Killed You 100 Years Ago?
The Inequality of Life Expectancy
A future IFOD will address why we age and if there are any potential treatments to extend life span beyond the “maximimum ceiling.”
There exists hundreds of medical research studies that confirm that replacing the hormones that begin to decrease between 40-55 yo increases life expectancy and decreases all cause mortality for both sexes. These hormones include testosterone for both sexes, estradiol for women, pregnenalone and thyroid hormone and finally stimulation of growth hormone.
Why is this not embraced as the foundation of preventive medicine?
Dr Kathy Maupin. St Louis, MO