We dream of a time when modern medicine will allow humans to live far beyond the lifespans we know today. But is there an upper limit of what's biologically possible? Yes, according to a new study, which suggests the maximum human lifespan probably tops out at about 150 years of age. The research taps into the idea of biological aging or senescence – how quickly our bodies deteriorate, which may or may not match our chronological age (how many birthdays we've celebrated). In this case, scientists developed a new way to interpret fluctuations in the numbers of different kinds of blood cells, resulting in a measure they called a dynamic organism state indicator (DOSI). Over time, it shows the resilience of our bodies slowly dropping – which is one of the reasons why it takes longer to recover from disease and injury when we're older. Assuming we can avoid disease, disaster, and ninja assassins for the course of our life, DOSI is a reliable method for showing when that resilience would give out completely, the researchers say. "Extrapolation of this trend suggested that DOSI recovery time and variance would simultaneously diverge at a critical point of 120-150 years of age corresponding to a complete loss of resilience," the researchers explain in their paper. Blood cell count information on more than half a million people taken from research databases in the UK, US, and Russia was analyzed, along with step count data on 4,532 individuals to measure the rate of decline in fitness in people's bodies. Blood cell counts could point to a range of problems in the body. To ensure it was a good general indicator of all-around health and recovery, the team used the step count data to double-check their thinking. Another discovery made from the data was a shift in the aging trajectories from age 35 and upwards, and then again from 65 and upwards. That matches up with some of the boundaries that are in place in society, such as the age when people tend to retire from elite sport and the age when people usually retire from full-time work. Further down the line, the researchers say the study could be used to inform treatments that can target diseases and illness without affecting biological resistance, and perhaps one day even extending the maximum possible lifespan further than it already is. We'll need a lot more research and a lot more data first, though. The new analysis is generally in line with previous studies that have mentioned a maximum lifespan of around 120-140 years – though, in any kind of number-crunching like this, there is a degree of educated guesswork and estimation. At the time of writing, the oldest age anyone has ever reached on record is 122 years and 164 days, by French woman Jeanne Calment. What this study posits is that without some pretty radical changes to our bodies on a fundamental level, it'd be hard to squeeze too many more years out of our fragile forms. "We conclude that the criticality resulting in the end of life is an intrinsic biological property of an organism that is independent of stress factors and signifies a fundamental or absolute limit of human lifespan," write the researchers. Source
