In France, super-centenarians are over-represented in the Antilles without us really knowing why

Super-centenarians, people aged at least 110, are increasingly numerous in France. According to an INED study, they are up to eight times more numerous in Guadeloupe and Martinique compared to mainland France, for reasons which remain to be clarified.

A study published Wednesday April 24 by INED, the National Institute of Demographic Studies, reveals that centenarians are more and more numerous in France to the point that a new category of population is also growing: super -centenarians, those people who reach or exceed 110 years old.

In 2022, 39 people died aged 110 or over, the overwhelming majority women. Unexpected discovery, “in proportion to the population, there are almost eight times more super-centenarians in Guadeloupe and Martinique than there are in mainland France”specifies France Meslé, demographer, research director at INED and co-author of the study.

franceinfo: What was the objective of your study?

France Meslé: The first idea is to show the truly spectacular increase in very old people, that is to say over 105 and even 110 years old. And what we want to show is that this increase, initially, is mainly due to the drop in mortality at older ages. The generations born in the 19th century were exhausted very quickly in number because there was very high infant mortality, followed by high mortality throughout life, so that they did not reach certain ages, like 80 or 90 years old, only a very small proportion of the generation which was then subject to increasingly higher risks of death. She disappeared very quickly and did not have time to reach 105 years. But from the end of the 19th century, the generations that were born first saw infant mortality decrease, as well as mortality throughout life, so that they were able to bring fairly large contingents up to at a fairly high age and therefore allow enough people to live another ten years, and therefore exceed 105 or 110 years.

In your study, you mention the astonishing case of the Antilles.

It’s a bit of a chance discovery of our work. By checking all the cases of death at very high ages, that is to say beyond 110 years, we realized that Guadeloupe and Martinique were over-represented in these super-centenarians, if we take into account of the size of the population. In proportion, there are almost eight times more super-centenarians in Guadeloupe and Martinique than there are in mainland France. The question was to try to understand this state of affairs.

The first thing is to verify that it was really real. When we find a case of a person who died over the age of 110, to be really sure that there was not an error at some point, we go back to the civil status and the birth certificate of the person to check that there is indeed a person born 110 years earlier who corresponds to the person who died 110 years later. This had been done for the Antilles, but we had a little doubt, we said to ourselves that in these overseas departments, the civil status perhaps did not function perfectly at the end of the 19th century or the beginning of the 20th. century. But all the checks that have been made, by studying the families of these super-centenarians, by retracing their life course, have shown that this is the case, these women are indeed well over 110 years old.

How can we explain this particular situation?

We have no ready-made explanation, we are talking about a certain number of hypotheses. Perhaps the environmental context was more favorable in these islands, in environments that were a little more closed than in mainland France. And then, there are also other hypotheses which revolve around the idea of ​​population selection, which would carry more important longevity genes. This might be a bit of a random selection. Other places where people live longer have been noted, such as certain regions of Sardinia in Italy, the island of Okinawa in Japan, the island of Ikaria in Greece, etc.

“This may also be a selection that could be linked to the history of slavery of these West Indian populations.”

France Meslé, demographer at INED

at franceinfo

The idea behind it would be that if these enslaved people suffered extreme conditions and in particular during the crossing of the Atlantic, this would have contributed to selecting a certain type of population which, for those who managed to survive, would be more resistant and perhaps more carrier of longevity genes. This over-representation does not exist in Reunion Island, whose population is also made up mainly of descendants of slaves. However, they did not cross the Atlantic, which could explain this phenomenon particular to the West Indians. We were able to trace the genealogy of many of these super-centenarians and we saw that all their ancestors were slaves. That said, this is also the case for a large part of the population of the Antilles who did not necessarily survive to be 110 years old. We really need to refine genetic research if we want to go further into these hypotheses and confirm or refute them.