Variability and persistence in inflation reshape human population dynamics by amplifying sensitivity and eroding demographic buffering

Inflation affects human fertility and survival, and persistent inflation can translate into fluctuations in annual population growth rate. However, existing studies have not yet systematically examined the impact of inflation on long-term growth rates across multiple populations. Here, using high-resolution inflation and demographic data for 32 countries from 1971-2024, we examine whether high inflation variance and autocorrelation amplify the sensitivity of the long-term growth rate to inflation. Additionally, we examine whether increasing inflation variance and autocorrelation adversely affect humans capacity for demographic buffering, i.e., reducing the temporal variance in vital rates most sensitive to growth. To do so, we construct inflation-dependent matrix population models using a hierarchical Bayesian framework. We then calculate the stochastic sensitivity and elasticity of population growth rate to inflation to quantify demographic buffering across a variance-autocorrelation parameter space for inflation. Our results show that the stochastic sensitivities of growth rate increase with variance and autocorrelation in inflation. However, we find partial support for the expected adverse effects of inflation variance and autocorrelation on humans capacity to buffer against inflation. Our framework offers a valuable tool to examine the impact of resource uncertainty on life history strategies in stochastic environments. We discuss how our framework can be extended to study the resource-dependent population dynamics within variable environments and across the tree of life.