World population densities: convergence, stability, or divergence?

Taylor’s law states that the variance of population density in a given set of areas is a power function of its mean. When the exponent is equal to 2, the distribution of population densities between areas remains unchanged; when it is less than 2, the distribution converges toward the uniform distribution; when it is greater than 2, the densities become increasingly different from each other over time. The exponent takes the value 2 for East Asia, the Pacific, and South Asia. It takes a value greater than 2 for sub-Saharan Africa because the ongoing demographic transition and intense urbanization are redistributing the population over the territories. The exponent is lower than 2 for the other regions of the world, which have completed their demographic transition and where the rural exodus has been completed.