What is the human lifespan

Is there a natural maximum age for humans?

Life without limit? Increasing the human lifespan to infinity is probably not possible. This is now suggested by data analyzes by US researchers: Despite all the advances in medicine and the like, there seems to be a natural upper limit for the maximum possible age - and we reached this limit two decades ago. To be older than 120 is therefore extremely unlikely in the future.

In 1928, the American statistician Louis Dublin postulated a maximum human life expectancy of 65 years. Mankind has long since passed this threshold in many countries. Our average life expectancy has been rising almost continuously since the 20th century - and the oldest among us are breaking records again and again: The best service life in terms of service life is currently 122 years.

Will we hit Methuselah one day?

Thanks to more and better food, the development of antibiotics and less physically difficult work through modern technology, we have immensely increased our longevity. New advances could even make it possible to take them even more to the extreme: will one day be able to surpass the fabulous age of the biblical Methuselah and live to be a thousand years old?

Scientists working with Xiao Dong from the Albert Einstein College of Medicine in New York don't believe that. The geneticist and his colleagues have analyzed data from the Human Mortality Database on human mortality in more than forty countries - and have come to the conclusion that the maximum possible lifespan has a natural limit.

More and more centenarians

When evaluating the data, the researchers found that people have been getting older since 1900. The proportion of the population that reaches the age of 70 or more increases with the calendar year of birth. Accordingly, the average life expectancy in the countries under review seems to be increasing continuously.

But a look at the group of people over centenarians showed that this curve will probably not continue indefinitely. This is how more and more people are turning 100 years old. After that, however, the survival rate drops rapidly - regardless of the year in which the people were born. In short: To live much older than 100 is unlikely even in our modern age.

Already lived a lot: reaching old age is no longer an exception today. Few of them live much older than 100. © Zoran Zeremski / thinkstock

Limit already reached?

In search of further clues, the scientists looked at data from the International Database on Longevity. It registers the “Methusalems” among people and shows who has broken an age record, when and where. The team focused on those who were over 110 years old between 1968 and 2006 in the four countries with the greatest number of particularly long-lived (USA, France, Japan, Great Britain).

It showed that between the 1970s and the 1990s, the age of death for those over centenarians rose dramatically, but reached a plateau around 1995 that continues to this day. For Xiao Ding and his colleagues, this is a clear indication that the maximum possible lifespan of a person has a limit.

"And our data suggest that this limit has already been reached - namely in the 1990s," says co-author Jan Vijg. Interesting: In fact, the beginning of the plateau in the age curve coincides with the death of French woman Jeanne Calment in 1997. She died at the age of 122, making her the oldest known person in the world.

125 years is the maximum

On the basis of their analyzes, the scientists estimate the average maximum service life to be 115 years. According to their model, the maximum possible deviation from this average is 125 years. This age is therefore the absolute limit of an individually possible lifespan. In terms of probabilities, the calculations show the chance that a person will live to be 125 years or older in any year is less than one in 10,000.

As the researchers emphasize, this does not mean that the maximum age is controlled by an isolated genetic “death program” that leads to aging processes and ultimately to the end of life. Rather, a multitude of other genetically fixed life events such as the development of diseases inevitably let our life clock run down.

Better to get healthier than to get older

"New advances in the fight against infections and chronic diseases can drive the average life expectancy even higher in the future - but probably not the maximum possible lifespan," says Vijg. "To do that, medical breakthroughs would have to overcome the numerous genetic variants that seem to determine human lifespan together."

Instead, so the scientists believe, research should focus on how to maintain health in old age. Just last year, a study by the World Health Organization (WHO) showed that living longer often means suffering longer. Accordingly, a long life is often associated with impairments due to incurable diseases. According to this WHO report, almost a quarter of all 70 to 85 year olds in Germany suffer from five or more diseases at the same time. (Nature, 2016; doi: 10.1038 / nature19793)

(Albert Einstein College of Medicine, October 6, 2016 - DAL)

October 6, 2016