Intuitively, there should be a relationship between your chance of death and how rapidly and completely you recover from illness. This parameter is a measure of your ability to maintain homeostasis — your normal physiological equilibrium — and is known as resilience. In fact, ageing can be defined as the loss of ability to maintain homeostasis. Typically, the younger the person, the better they are at recovering rapidly from illness.
To conduct the modeling study, the researchers took blood samples from over 70,000 participants aged up to 85 and looked at short-term changes in their blood cell counts. The number of white blood cells a person has can indicate the level of inflammation (disease) in their body, while the volume of red blood cells can indicate a person's risk of heart disease or stroke, or cognitive impairment, such as memory loss. The researchers then simplified this data into a single parameter, which they called the dynamic organisms state indicator (Dosi).
Changes in Dosi values across the participants predicted who would get age-related diseases, how this varied from person to person and modeled the loss of resilience with age. These calculations predicted that for everyone — regardless of their health or genetics — resilience failed completely at 150, giving a theoretical limit to human life span.
But estimates of this type assume that nothing new will be done to a population, such as, no new medical treatments will be found for common diseases. This is a major flaw, since significant progress occurs over a lifetime and this benefits some people more than others.
For example, a baby born today can rely on about 85 years of medical progress to enhance their life expectancy, while an 85-year-old alive now is limited by current medical technologies. As such, the calculation used by these researchers will be relatively accurate for old people but will become progressively less so the younger the person you're looking at.
The Dosi limit for maximum life span is about 25 percent longer than Jeanne Calment lived. So if you're planning to beat it (and her), you need three important things.
First is good genes, which makes living to be more than 100 unassisted a good bet. Second, an excellent diet and exercise plan, which can add up to 15 years to life expectancy. And third, a breakthrough in turning our knowledge of the biology of ageing into treatments and medicines that can increase healthy life span.
Currently, adding more than 15 to 20 percent to healthy life span in normal mammals is extremely difficult, partly because our understanding of the biology of ageing remains incomplete. But it's possible to increase the life span of much simpler organisms — such as roundworms — by up to 10 times.
Even given the current pace of progress, we can confidently expect life expectancy to increase because it has been doing this since Gompertz was alive in the 1860s. In fact, if you spend a half-hour reading this article average life expectancy will have increased by six minutes. Unfortunately, at that rate, the average person won't live to 150 for another three centuries.
This article is republished from The Conversation under a Creative Commons license. You can find the original article here.
Richard Faragher is a professor of biogerontology at the University of Brighton. He is a member of the Board of Directors of the American Federation for Aging Research (AFAR) and the Biogerontology Research Foundation. He is also a member of the scientific advisory board of the Longevity Vision Fund.
