Are blue zones Disappearing?

The historic rise in human longevity among long-lived national populations has slowed down in this century. One proposed explanation is that, as survival to older ages becomes more common, additional gains depend increasingly on reducing mortality at ages where the baseline hazard is dominated by biological aging, making further improvements harder to achieve without interventions that modify aging itself. If this interpretation is correct, then geographically defined longevity hotspots known as blue zones, should show early or pronounced deceleration and/or convergence as other populations catch up. We test this using period vital statistics from three widely cited blue zones: Okinawa (Japan) and in selected municipalities in Sardinia (Italy) and Nicoya (Costa Rica). We compare each blue zone to (i) its national population, and (ii) to three contemporaneous long-lived countries (a composite) with the highest period life expectancy at the time each blue zone was first reported in the scientific literature (Japan, Hong Kong, and France). Using period demographic metrics of longevity (life expectancy at age 70 [e(70)], survival (conditional survival from age 70 to 100), and the prevalence of centenarians from 1991-2019 for Okinawa, for males we found that in the year each was declared a blue zone, e(70) was an average of 9.8% higher relative to composite; conditional survival from ages 70 to 100 was ~2-fold that of composite; and the prevalence of centenarians per 100,000 in Okinawa was 2.7-fold greater than composite. Similar but highly variable patterns were observed for females. All three blue zones were revalidated here as longevity outliers in the year in which they were declared. We also found a broad deceleration in the rate of improvement in these metrics for Okinawa and Nicoya after ~2010, defined as a reduction in the slope of improvement (and in some cases a decline) compared with earlier periods. Overall, the demographic distinctiveness of the three blue zones has narrowed since their initial identification. We attribute this convergence to (1) catch-up among national and other long-lived populations, (2) a general slowdown in late-life mortality improvement consistent with increasing dominance of aging-related causes at advanced ages, and (3) cohort replacement that erodes historically favorable early-life, midlife, and behavioral exposures that characterized early-20th-century cohorts in these regions.