To my mind far too much effort is expended on trying to figure out the epidemiology of the tiny fraction of humans who manage to live a fair way past one hundred years of age. For one, there just aren't enough of them to generate truly robust data from which conclusions can be drawn. People are still arguing over the legitimacy of many of the cases, including Jeanne Calment. Gathering and vetting data on the age of very old people is inherently challenging in its own ways. As the authors of today's paper point out, we should be more suspicious than we are of claims of extreme longevity. You might compare their position with another recent discussion on this topic that presents similar conclusions - the quality of the data on ages of extremely old people just isn't great. But beyond legitimacy, small data sets naturally come with all sorts of other problems. The law of small numbers applies: a low number of data points tends to exhibit false trends that will vanish given more data points.
The more important issue here, however, is that this simply doesn't matter! It really is of little importance as to the statistics of how the small number of oldest humans age to death in the absence of rejuvenation therapies. It is unimportant because rejuvenation therapies will soon arrive in the clinic. The first experimental rejuvenation therapies worthy of the name are available now for the adventurous to try. It won't be long before near everyone who reaches old age will have undergone one or more forms of treatment to slow or reverse the progression of aging. The world of natural aging, in which there were no deliberate attempts to intervene in the mechanisms that cause aging, is soon to vanish. In this environment of rapid progress in biotechnology, the demographics of unmodified aging are of increasingly little importance. Instead, the focus must be on forging ahead with the development of rejuvenation biotechnology, the means to prevent and reverse the suffering and disease of aging.
The world longevity record for Jeanne Calment (122 years) is widely cited with great pride as the gold standard of the highest data quality for many decades. Yet even for this best documented longevity claim, some early doubts were expressed of her suspicious extremely outlying age. Still, most scientists and the public believe in the validity of the Calment longevity record. The situation is even more serious-our studies found that many longevity records for ages 105 years and older are often incorrect (see later). After age 105 years, longevity claims should be considered as extraordinary claims that require extraordinary evidence. Traditional methods of data cleaning and data quality control are just not sufficient. New, more strict methodologies of data quality control need to be developed and tested. Before this happens, all mortality estimates for ages above 105 years should be treated with caution.
Knowledge of true mortality trajectory at extreme old ages is important not only for actuaries but also for biologists who test their theories of aging with demographic data. Studies conducted in the 1990s suggest that the exponential growth of human mortality with age (the Gompertz law) is followed by a period of deceleration, with slower rates of mortality increase. These early studies, as well as studies on insects, convinced researchers of the universality of the mortality deceleration phenomenon, and until recently, there was no doubt among biodemographers and gerontologists that mortality slows down after the age of 80 years. At that time, several biological explanations of mortality deceleration and late-life mortality plateau were suggested. Reliability models of aging also suggest mortality plateau at advanced ages when assuming random loss of functional cells and other essential elements over time.
Recently, the common view about mortality deceleration at advanced ages has been challenged using both theoretical and empirical considerations. It was found that mortality of US extinct cohorts born after 1889 demonstrated the Gompertz-like trajectory in the age interval 85 to 106 years. In the study of old-age mortality in 15 low-mortality countries, Gompertz-like mortality growth was found at older ages for Australia, Canada, and the US and mortality deceleration for other studied countries.
It should be noted that hazard rate estimation at very old ages faces difficulties because of very small number of survivors to these ages, and age misreporting by older persons. Age misreporting is a big problem affecting estimates of mortality at advanced ages. It was found that even a small percentage of inaccurate data can greatly distort mortality trajectories at advanced ages and that age misreporting at older ages results in mortality underestimation. Taking into account that the accuracy of age reporting is positively correlated with education, it is reasonable to expect improvement in age reporting over time and less prevalent mortality underestimation or mortality deceleration at older ages for more recent birth cohorts. Indeed, it was found that late-life mortality in historically older US birth cohorts demonstrates stronger mortality deceleration compared to more recent birth cohorts. These results suggest that mortality deceleration observed in early studies of old-age mortality may be caused by age misreporting at older ages.