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While most of us can expect to live to be around 80, some people defy expectations and live to be over 100. In places like Okinawa, Japan and Sardinia, Italy, there are many centenarians. The oldest person in history – a named Frenchwoman Jeanne Calment – lived to be 122 years old. When he was born in 1875, the average life expectancy was around 43 years.

But how long can a human actually live? It’s a question people have been asking for centuries. While average life expectancy (the number of years a person can expect to live) is relatively easy to calculate, estimates of maximum life span (the highest age a human can reach ) are much more difficult to do. Previous studies have placed this limit near 140 years. But a more recent study suggests that the limit of human lifespan is closer to 150.

Calculation of service life

The oldest and still the most widely used method of calculating life expectancy, and therefore lifespan, is based on the Gompertz equation. It is the observation, made for the first time in the 19th century, that human death rates from the disease increase exponentially over time. Essentially, that means your risk of dying – from cancer, heart disease, and many infections, for example – doubles roughly every eight to nine years.

There is many ways the formula can be modified to account for how different factors (such as gender or disease) affect the lifespan of a population. Gompertz’s calculations are even used to calculate health insurance premiums – which is why these companies are so interested in whether you smoke, that you are married and anything else that might allow them to judge more precisely age at which you will die.

Another approach to determining how long we can live is to look at how our organs decline with age and compare that rate of decline to the age at which they stop functioning. For example, eye function and how much oxygen we use during exercise show a general downward trend with aging, most calculations indicate that organs will only function until the average person is around 120 years old.

But these studies also reveal increasing variations between people as they get older. For example, some people have kidney function that declines rapidly with age, while others have hardly changes at all.

Few people reach 100.
Dan Negureanu / Shutterstock

Today, researchers from Singapore, Russia, and the United States have taken a different approach to estimating maximum human lifespan. Using a computer model, they estimate that the limit of human lifespan is about 150 years.

Live to 150 years

Intuitively, there should be a relationship between your risk of death and how quickly and quickly you recover from the disease. This parameter is a measure of your ability to maintain homeostasis – your normal physiological equilibrium – and is known as resilience. In fact, aging can be defined as the loss of the ability to maintain homeostasis. As a general rule, the younger the person, the faster they recover from the disease.

To conduct the modeling study, the researchers took blood samples from more than 70,000 participants aged up to 85 and looked at short-term changes in their blood cell numbers. Number of white blood cells that a person has can indicate the level of inflammation (disease) in their body, while the red blood cell volume may indicate a person’s risk of heart disease or stroke, or cognitive impairment, like memory loss. The researchers then simplified this data into a single parameter, which they called the Dynamic Organism Status Indicator (Dosi).

Changes in Dosi values ​​in participants predicted who would contract age-related illnesses, how this varied from person to person, and modeled loss of resilience with age. These calculations predicted that for everyone – regardless of their health or genetics – resilience completely failed at 150, giving a theoretical limit to human lifespan.

But estimates like this assume that nothing new will be done for a population, for example, no new medical treatment will be found for common illnesses. This is a major flaw, as significant progress occurs over the course of life and it benefits some more than others.

For example, a baby born today can count on around 85 years of medical advancements to increase their life expectancy, while an 85-year-old living today is limited by current medical technologies. As such, the calculation used by these researchers will be relatively accurate for older people, but will gradually become less so, so the younger the person you are looking at.

Dosi’s limit for maximum lifespan is approximately 25% longer than that experienced by Jeanne Calment. So if you’re planning to beat him (and her), you need three important things. The first is good genes, which brings life more than a hundred without help a good bet. Second, a great diet and exercise plan, which can add up to 15 years to life expectancy. And finally, a breakthrough in transforming our knowledge of the biology of aging into treatments and drugs which can increase healthy lifespan.

Currently, adding more than 15-20% to healthy lifespan in normal mammals is extremely difficult, in part because our understanding of the biology of aging remains incomplete. But it is possible to increase the lifespan of much simpler organisms, such as roundworms, by up to ten times.

Even given the current rate of progress, we can expect life expectancy to increase with confidence, as it has been doing so since Gompertz was alive in the 1860s. In fact, if you spend half an hour to read this article the average life expectancy will have increased by six minutes. Unfortunately, at this rate, the average person won’t live to be 150 for three centuries.The conversation

Richard Faragher, professor of biogerontology, Brighton University

This article is republished from The conversation under a Creative Commons license. Read it original article.

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