This heightexpectancy “truth” is no more absurd or misleading than what most people are led to believe about human lifeexpectancy in prehistory.
Exhibit A: In an interview with NBC Nightly News,UCSF bio-physicist Jeff Lotz was discussing the prevalence of chronic back pain in the United States. The millions of people watching that night heard him explain, “It wasn’t until two or three hundred years ago that we lived past age forty-five,so our spines really haven’t evolved to the point where they can maintain this upright posture with these large gravity loads for the duration of our lives [emphasis added].”
Exhibit B: In an otherwise solid book about women in prehistory (The Invisible Sex),an archaeologist, an anthropologist, and an editor of one of the world’s leading science magazines team up to imagine the life of a typical woman they call Ursula, living in Europe 45,000 years ago. “Life was hard,” they write, “and many, especially the young and the old, died of starvation in winter and accidents of one sort or another, as well as disease.. Ursula [having had her first daughter at age fifteen] lived long enough to see her first granddaughter, dying at the ripe old age of 37 [emphasis added].”3
Exhibit C: In a New York Times article,4 James Vaupel, director of the laboratory of survival and longevity at the Max Planck Institute for Demographic Research, explains, “There is no fixed life span.” Dr. Vaupel points to the increase in life expectancy from 1840 to today in countries where the figure is rising quickest and notes that this increase is “linear, absolutely linear, with no evidence of any decline or tapering off.” From this, he concludes, “There’s no reason that life expectancy can’t continue to go up two to three years per decade.”
Except that there is. At some point, all the babies who can survive to adulthood, do. Further advances will be slight.
When Does Life Begin? When Does It End?The preceding numbers are just as fantastical as the ones we came up with for our average height expectancy estimate. They are, in fact, based upon the same erroneous calculation distorted by high infant mortality rates. When this factor is eliminated, we see that prehistoric humans who survived beyond childhood typically lived from sixty-six to ninety-one years, with higher levels of overall health and mobility than we find in most Western societies today.
It’s a game of averages, you see. While it’s true that many infants and small children died in prehistoric populations—as indicated by the larger numbers of infant skeletons in most burial sites—these skeletons tell us nothing about what constituted a “ripe old age.” Life expectancy at birth, which is the measure generally cited, is far from an accurate measure of the typical life span. When you read, “At the beginning of the 20th century, life expectancy at birth was around 45 years. It has risen to about 75 thanks to the advent of antibiotics and public health measures that allow people to survive or avoid infectious diseases,”5 keep in mind that this dramatic increase is much more a reflection of increased infant survival than of adults living longer.
In Mozambique, where one of us was born and raised, the average life expectancy at birth for a man is currently, tragically, about forty-two years. But Cacilda’s father was ninety-three when he died, riding his bicycle right to the end of the road. He was old. A forty-year-old is not. Not even in Mozambique.
