The oldest verified person living today – the current front-runner in the longevity race – is Kane Tanaka, who was born in Fukuoka, Japan, on January 2, 1903. She is 118 years old. If Kane Tanaka survives to age 200, making the answer ‘yes’, this will be in the year 2103. If she fails, but someone else does it, we must wait a bit longer. If no one has done it by 2221, the answer will be ‘no’.
Clearly, a definitive answer is going to take a while. However, can we get some idea of the likelihood of a yes/no answer in other ways? There are three things at least we can consider. Firstly, could it happen just by chance? Realistically, Kane Tanaka’s statistical chance of surviving even to her next birthday, given recorded mortality rates among supercentenarians, is no better than 50:50. To do it 81 more times beyond this is unimaginable.
The next possibility arises from what history has taught us about human longevity. Over the last two centuries, in the USA and other high-income countries, the average length of human life has doubled. To reach 200 is effectively to double it again. To acquire further insight, we need to look beneath the hood of the longevity engine.
From around 1800 to the mid-20th century, we gained life expectancy through reducing the death rates in the early and middle years of life, chiefly by control of infections through hygiene, vaccination and antibiotics. By the late 20th century, there was little room to improve further in this regard, but life expectancy carried on growing at the same rate as before, only this time it was because older people were dying less. This told us something new: the aging process is more malleable than had been thought. Nevertheless, although the average lifespan continued to grow – at a rate over 2 years per decade – the lifespans of the longest-living individuals have remained stubbornly static. Might this indicate a limit?
We now turn to biology. Could our burgeoning knowledge of the underlying mechanisms of aging open paths to modifying the intrinsic processes that drive the body into decline? Most experts now agree there is no program that actively causes us to age and die. On the contrary, our bodies are programmed for survival not death. The reason we do not live forever is that evolution had higher priorities than wasting energy on better maintenance of our bodies than was needed in our ancestral ‘wild’ environment, where many things were likely to kill us relatively young.
The science of aging has a buzz that excites many with the possibilities that may lie ahead. We would be working with the grain of our biology, rather than against it, in trying to enhance survival, so can we boost our maintenance systems to deliver longer, healthier lives? It ought to be possible, but when?