Lifespan-extending treatments increase variation in age at time of death

A key goal in aging research is not just to extend life, but to ensure more people live longer and healthier lives with less variation in age at death, a concept known as “squaring the survival curve.” Using a recent meta-analysis, Dr. Tahlia Fulton and Associate Professor Alistair Senior from the University of Sydney School of Life and Environmental Sciences have re-examined how dietary restriction and two related drugs, rapamycin and metformin, affect variation in age at death in vertebrates.

The work appears in Biology Letters.

While two of the treatments increased average lifespan, all three increased variance. This means that current lifespan-extending interventions do not square the survival curve. Instead, the gains in average lifespan are matched by proportional increases in variability.

Dr. Fulton said, “These approaches can make animals live longer, but the benefits aren’t shared equally. Without more information, the outcome looks like a biological lottery. We’re working to understand why, so future longevity science helps everyone.”