Investigating the effect of mortality shocks on humans is difficult in the absence of laboratory experiments. However, some events in human history serve as natural experiments. Using data for Australian prisoners during WWII and for the Ukrainian Famine in 1933, I analyzed the effect of sudden changes in external conditions on the rate of aging. This may help to decide whether the rate of aging is sensitive to the environment or is stable. The mortality of the prisoners of war was higher during the imprisonment but the slope of the curve did not change. During the Ukrainian Famine, the curves in the years of crisis converged at old ages. By adopting a cohort perspective I found evidence of selection that could be the cause of the convergence. The analysis suggests that sudden and transitory exposure to severe conditions shifts the mortality curve upward proportionally at all ages, leaving the rate of aging unchanged.
