Human lifespan may have maxed out

Throughout the 20th century humans have been living longer. However, a new study suggests that this trend will not continue.

 The study, published today in Nature, looked at data from the Human Mortality Database and found that the improvement in human survival peaked in around 1980. The researchers believe that genetically fixed life-history traits mean humans are unlikely to ever exceed 122 years old, which is the oldest documented age of death. The study’s corresponding author Jan Vijg, from the Albert Einstein College of Medicine in New York, told us more.

ResearchGate: Could you explain the research you did and the method you used in your analysis?

Vijg: We tested if human maximum life span is fixed or fluid and we found it to be fixed at around 115 years. We did this by looking at the maximum reported age at death in France, Japan, the United Kingdom and the United States. Firstly, we tested if improvement in survival also shifts to older age groups over time. We showed that improvement in survival in the oldest age group peaked in about 1980. This suggests – but does not prove – that we are reaching a maximum lifespan. Then we tested the maximum reported age at death since the 1960s. At first, this increased, but only up until the early 1990s. It then seemed to settle on a plateau, or even decline slowly, which is why we believe there is strong evidence that we have reached our ceiling.

RG: Why do you believe that humans have a natural age limit that is unlikely to be exceeded?

Vijg: Probably because the multiple longevity assurance systems humans have to prevent or fix damage and respond to stress are limited. This is also likely to be true for all animal species. A mouse lives much shorter than a human, possibly because it possesses inferior longevity assurance systems and can only get rid of damage and stress up until about three years.

RG: In a recent study from the Mayo Clinic, scientists were able to significantly extend the lifespan of mice. Do you believe that, in the future, medical interventions will also overcome the ‘natural limit’ of human life that you found in your research?

Vijg: No, mice are not humans, and those were laboratory mice, which is not the same as wild mice. I can of course not rule out the possibility that we will develop some drug that extends our maximum lifespan, but I doubt that.

RG: What led you to look into a potential limit of human lifespans?

Vijg: I was interested in why we never produced longer-lived humans than Jeanne Calment, who died when she was 122. She proved to be an outlier.

RG: What are the next steps in this research?

Vijg: Basically, we are just waiting to see what happens next. The other thing to do is to find out the basic mechanisms of aging and the exact nature of the longevity assurance systems – maybe there are master regulator genes that we can play and still extend the maximum lifespan. As I said, highly unlikely, but who knows. For the moment it’s important to work on interventions that improve health span.

Featured image courtesy of Titoy.