We asked the question for you | Will the increase in centenarians shake up the planet?

For 70 years, the number of centenarians has exploded in “rich” countries, and this is apparently only the beginning. Longevity champions now dream of living 120 years. But how high can human life expectancy increase before the planet, already overexploited, no longer provides?

Who among us can afford to swallow the equivalent of a bowl of cereal filled with expensive supplements every morning, between two appointments at state-of-the-art medical laboratories? For the moment, only a handful of immortal aspirants, we discover in Nathalie Collard’s captivating file on the new champions of longevity^⁠1. But what will happen if surviving to 100 years – or even 120 years – becomes common one day, without requiring so much effort? What if four or five generations suddenly coexist on the planet?

Once verified, this is not a pure utopia. Mortality at advanced and very advanced ages is falling relentlessly in high-income countries, explains one of the greatest demographic experts in the field, Nadine Ouellette, professor at the University of Montreal. “In Canada and the United States, progress is significant and rapid. »

In less than a century, the number of Quebec centenarians has exploded and continues to rise at an almost exponential rate. The pool of semi-supercentenarians (105 to 109 years) and supercentenarians (110 years or older) is also swelling.

Before the pandemic, the most common age at death exceeded 90 years in Quebec, compared to around 80 years in 1970. This represents an average increase of two years per decade.

In just 50 calendar years, the most common lifespan could reach 100 years, we deduced.

Demographers rely on much more complex operations to carry out their projections, and developments do not always occur in a straight line, “but this shortcut is not completely insane”, assesses Professor Nadine Ouellette with indulgence.

New pandemics, natural disasters, or other crises could well stall progress at different ages, as the opioid crisis and inequality already do in the United States.

But unexpected gains could just as easily arise. Because since the mid-18th century^e century, great medical and social advances have increased longevity by unforeseen leaps, indicates Professor Nadine Ouellette. “No one saw the cardiovascular revolution coming,” she illustrates.

Other important battles now remain to be won, for example, against cancer.

Meanwhile, although the most common lifespan still varies depending on the cause of death, it is increasing at about the same rate, whether it is heart or cerebrovascular diseases, or even four common cancers. “This discovery stunned us,” explains Professor Nadine Ouellette.

At Boston University, where she is a visiting scholar, she works closely with the geriatrician responsible for the world’s largest study of centenarians (New England Centenarian Study). “This type of research can help us find what these people have in common, to elucidate the factors of longevity. »

Poor planet?

How can we envisage such a perspective, even distant? No one can be against increasing life expectancy, replies Alain Létourneau, professor of philosophy at the University of Sherbrooke.

But if nothing changes, he finds it difficult to see how extending human existence by 15% or more would be ecologically viable. “It would generate even more waste, pollution and products of all kinds which would return to the ecosystems,” says the professor, who studies, among other things, adaptation to climate change.

“And as the population increases, meeting needs becomes more complicated. Resources are not infinite. The food plate is even shrinking. »

Desertification will make large sections of countries “completely uninhabitable and uncultivable,” as is looming in Spain, he says. While salinization caused by rising water levels is destroying rice crops in Asia.

We would also lack space for accommodation: “The Far North, we won’t be moving in with our condos tomorrow! »

For many demographers, population growth also represents a threat, indicates Richard Marcoux, director of the sociology department at Laval University and the Demographic and Statistical Observatory of the Francophone Space.

“But for others, it is the consumption patterns that are most important. The Earth could support more people who behave properly. But it is certain that if the entire planet behaves like the average American, we are in trouble! »

Given the decline in fertility worldwide, the United Nations projects that the population will stop growing from 2100. But who knows what will really happen?

In the 20th^e century, the United Nations, the World Bank and researchers were convinced that there must be a ceiling to the average lifespan, recalls Professor Nadine Ouellette. However, she says, “the upper limits announced for life expectancy have, in turn, been contradicted by reality. Human beings have always had a great desire to live. »

1. Read the file “Will we blow out 120 candles one day? »

What do you think ? Participate in the dialogue