"On average, people live longer, but the very oldest among us have not gotten older over the last 30 years," Professor John Einmahl told the Agence France-Presse.
"There is certainly some kind of a wall here.
"Of course the average life expectancy has increased. Nevertheless, the maximum ceiling hasn't changed."
They determined that a person's maximum lifespan plateaus in their nineties and was unlikely to ever increase beyond 115.
The oldest-ever living person was French woman Jeanne Louise Calment, who was born in 1875 and died in 1997 at age 122 years and 164 days.
However Einmahl said there are rare outliers when occasionally a few people do surpass that lifespan wall.
A similar American study last year also concluded 115 years as the average maximum human lifespan.
Einmahl is aiming to have his study published in the next month or so, which may reveal the key to a longer life.
