A thousand years ago, you would have lived to about 26, before some horrible death befell you. During the Iron Age, that was the average life span of humans and death by some large beast would have been a mercy.
Better to go quickly than have a rotten tooth contaminate your blood and poison you from the inside.
These days, modern medicine, nutritious foods and penicillin mean we’re living longer. This is often the bane (or blessing, depending on your vantage point) of social and healthcare systems, which are having to adapt to bear the load of an ageing population, but it has reignited the question: is there a physical limit to the human life span?
Is there a point at which even the healthiest body gives up?
The longevity record holder, Frenchwoman Jeanne Calment, lived to 122 years and 164 days.
— DEMOGRAPHERS AND BIOLOGISTS CONTEND THERE IS NO REASON TO THINK THE RISE IN MAXIMUM LIFE SPAN WILL END SOON.
She lived through Thomas Edison’s discovery of the phonograph and the unveiling of the first mobile phone.
Calment, who died in 1997, has now held the title of the most long-lived human on record for 20 years. This has led researchers to argue that, while there was an initial increase in the maximum life span of humans, these gains have tapered off, leading to a plateau of age.
The scientific debates are not, increasingly, about biology. They are about statistics. In a paper published in the journal Nature late in 2016, the researchers turned to the Human Mortality Database, which tracks mortality and population data for 39 countries, to gauge the trends in maximum human age. Unfortunately, SA did not make the list — nor any other African country.
The gist of the researchers’ argument is this: while there have been gains in maximum life span, with many people now reaching the age of 100, these have slowed and humans’ maximum age has remained fairly static.
"Demographers as well as biologists have contended there is no reason to think that the increase in maximum life span will end soon," said senior author Jan Vijg, a professor of genetics at the Albert Einstein College of Medicine in the US.
"But our data strongly suggest that it has already been attained and that this happened in the 1990s."
They argue that there is a genetically coded, species-specific limit to how old humans can become.
These researchers determined that 115 was the maximum average age of humans and that 125 was the golden number, the upper limit of human age.
But as in all scientific arguments, not everyone agrees with their numbers, or even the idea that there is an age limit.
In a response, also published in Nature, researchers from McGill University in Canada question the researchers’ statistics, saying that by comparing all these different countries, the data is "noisy" and does not take into account different healthcare systems, population sizes and genetic compositions.
"We just don’t know what the age limit might be. In fact, by extending trend lines we can show that maximum and average life spans could continue to increase far into the foreseeable future," says co-author Siegfried Hekimi, a professor of zoology and developmental biology.
All of these arguments, though, look at human longevity through the lens of current technologies.
Craig Venter, who created the first synthetic genome, founded Human Longevity, whose sole purpose is to push the boundary of human age.
If you want to live forever you might one day be able to — if you are still alive at the time.
• Wild is a science journalist and author.
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