Fig. (1) Example of a quantitative Gompertz fit of the survivorship curve of the Dutch population. The observational data (yearly survival data); the line is the best fitting Gompertz curve. The bold interrupted line is the population probability curve, which is the derivative of the Gompertz curve, being time-asymmetric and deviating from a Gaussian distribution. This example shows a deceleration of mortality and subsequently the mortality rate at an advanced age. Such deceleration is not explained by assuming the decrease in the size of the population at old age.