Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Individual lifespans are becoming more similar

22.11.2016

The higher the life expectancy in a society, the smaller the difference between the ages at which people will die. Scientists discover a novel regularity for vastly different human societies and epochs.

On average, as lives get longer, the difference in the age at which people die becomes smaller. By analyzing data from 44 countries, researchers have now proven that life expectancy and the variation of individual lifespans are tightly bound together by a mathematical relationship. If life expectancy decreases in times of crisis, then, according to the same mathematical logic, the distribution of the lengths of lives widens.


MPIDR_US_death-spike_getting_sharper_EN

© 2016 Max Planck Institute for Demographic Research

“Since life expectancy very probably continues to rise, we can expect that fewer people have to die earlier than the average,” says Alexander Scheuerlein, scientist at the Max Planck Institute for Demographic Research (MPIDR) in Rostock, Germany. Scheuerlein has now published these results on lifespans together with MPIDR director James Vaupel and an international team of researchers in the science journal PNAS.

Fewer people have to die prematurely

Among women in the US, the effect accounts for a compression of mortality by ten years between 1933 and 2014 (see graph). In 1933, American women had a life expectancy of 62.8 years, while half of all deaths occurred within a time span of 26.3 years around the average age of death. In contrast, by 2014, life expectancy had risen by almost 19 years to up to 81.3 years, while the time span that half of all deaths occurred in had shrunk to only 16.3 years.

According to Scheuerlein, the continuing convergence of the ages at death not only means that less people are dying clearly prematurely, but also that less people are living far beyond the average age of death. “The extent to which people benefit from gains in lifespan is becoming increasingly similar,” says Scheuerlein.

One rule for vastly different societies

This relationship between life expectancy and the converging of the ages at death can be
observed not only over time within a single country, but across very different countries, historical epochs, and societies—and between men and women. No matter which types of populations the researchers compared, they always found a fixed relationship between the difference in life expectancy levels and the difference in the variance in the distributions of deaths over age.

The same mathematical conditions apply even to extreme cases. For example, this is true for modern Japanese women, who hold the world record with a life expectancy well beyond 80 years. It also applies to traditional hunter-gatherer societies (with a life expectancy around 40 years), and the historic population of freed US slaves in Liberia, who temporarily had an average lifespan of only a few years.

Given the diversity of the human populations who appear to be governed by this newly
discovered rule, it is not yet possible to determine its causes, Scheuerlein says. “The universality of the relationship is striking. The only thing that is obvious to us right now is that it must have to do with the sociocultural way humans organize their societies.”

Increasing length of life despite low infant mortality

The PNAS study confirms recent research which suggests that gains in life expectancy are to be expected at higher ages, Scheuerlein points out. In the past, individual lifespans have been more diverse mainly due to high infant mortality. Deaths had accumulated in two distinct age groups, that of early childhood and, for those who survived, that of adulthood. As the centers of these groups had been quite distant, it was no surprise that when infant mortality decreased to almost zero, the variation of lifespans shrunk and life expectancy rose at the same time.

Meanwhile infant mortality has been at sustained low levels for many years, and the vast majority of deaths is centered around higher ages. Nevertheless, recent developments also follow the newly discovered rule. The age range within which most deaths occur is still becoming narrower, even though the time span for this process has already become considerably smaller than in the past and now takes place later on in the second half of life. Simultaneously, life expectancy continues to reach ever-higher values. “Our newly discovered rule adds to a growing body of research that does not give any evidence that humans are approaching a looming limit to life expectancy,” says Scheuerlein.

About the MPIDR

The Max Planck Institute for Demographic Research in Rostock (MPIDR) investigates the
structure and dynamics of populations. It focuses on issues of political relevance such as
demographic change, aging, fertility, the redistribution of work over the course of life, as well as aspects of evolutionary biology and medicine. The MPIDR is one of the largest demographic research bodies in Europe and one of the worldwide leaders in the field. It is part of the Max Planck Society, the internationally renowned German research society.

http://www.demogr.mpg.de

Contact
Alexander Scheuerlein – MPIDR author of the article
(speaks English and German)
TELEPHONE +49 381 2081 – 212
E-MAIL scheuerlein@demogr.mpg.de

Silvia Leek – MPIDR Press Department
TELEPHONE +49 381 2081 – 143
E-MAIL presse@demogr.mpg.de

This press release, the graphics in high resolution and the corresponding data can be found online at http://www.demogr.mpg.de/go/lifespan-equality

Original publication:

Lenart, Laszlo Nemeth, Alexander Scheuerlein, Jonas Schoeley, Catalina Torres, Virginia Zarulli, Jeanne Altmann, Diane K. Brockman, Anne M. Bronikowski, Linda M. Fedigan, Anne E. Pusey, Tara S. Stoinski, Karen B. Strier, Annette Baudisch, Susan C. Alberts, James W. Vaupel: The emergence of longevous populations, PNAS, DOI 10.1073/pnas.1612191113

Silvia Leek | Max-Planck-Institut für demografische Forschung
Further information:
http://www.demogr.mpg.de

More articles from Social Sciences:

nachricht Sibling differences: Later-borns choose less prestigious programs at university
14.11.2017 | Max-Planck-Institut für demografische Forschung

nachricht Visual intelligence is not the same as IQ
09.11.2017 | Vanderbilt University

All articles from Social Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Shape separates substance

Japanese researchers show the phase separation of two substances depends on the topology of the pore

Researchers at University of Tokyo Institute of Industrial Science (IIS) report a new physical model that shows how the topology of a porous material...

Im Focus: New study visualizes motion of water molecules, promises new wave of electronic devices

A novel approach to studying the viscosity of water has revealed new insights about the behavior of water molecules and may open pathways for liquid-based electronics.

A team of researchers led by the Department of Energy's Oak Ridge National Laboratory used a high-resolution inelastic X-ray scattering technique to measure...

Im Focus: Research trip to the mouth of the Amazon River: on the trail of the ocean’s material cycle

It is by far the most abundant river in the world. One fifth of the Earth’s entire freshwater supply flows from its mouth into the Atlantic pushing the ocean’s salt water several hundred kilometers out to sea. In April, Andrea Koschinsky, Professor of Geochemistry at Jacobs University, will travel to the estuary of the Amazon – as head of a recently approved, interdisciplinary research project on board the research ship, Meteor.

The Amazon River is almost 7,000 km long and is not only tremendously abundant but it also transports large quantities of trace metals such as iron and copper...

Im Focus: The Coldest Chip in the World

Physicists at the University of Basel have succeeded in cooling a nanoelectronic chip to a temperature lower than 3 millikelvin. The scientists from the Department of Physics and the Swiss Nanoscience Institute set this record in collaboration with colleagues from Germany and Finland. They used magnetic cooling to cool the electrical connections as well as the chip itself. The results were published in the journal Applied Physics Letters.

Even scientists like to compete for records, which is why numerous working groups worldwide are using high-tech refrigerators to reach temperatures as close to...

Im Focus: Star mergers: A new test of gravity, dark energy theories

Observations of neutron star collision challenge some existing theories

When scientists recorded a rippling in space-time, followed within two seconds by an associated burst of light observed by dozens of telescopes around the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Shape separates substance

29.12.2017 | Materials Sciences

New structure of key protein holds clues for better drug design

29.12.2017 | Health and Medicine

Researchers describe first-ever hybrid bird species from the Amazon

29.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>