High Variability in Vital Rates with Positive Autocorrelation Negatively Affects Humans' Capacity to Buffer Against the Variable Inflation Environment

Rahul Mondal, International Institute for Population Sciences (IIPS)
Samuel Gascoigne, University of Aberdeen
Maja Kajin, Department of Biology, University of Ljubljana, Slovenia
Udaya S. Mishra, Centre for Development Studies
Roberto Salguero-Gomez, Department of Biology, University of Oxford, UK

Decades of ecology and evolution research improved our understanding of how natural populations respond to environmental stochasticity. However, these theories and emerging predictions applied to non-human populations have rarely been applied to human species. Here, we cross that bridge by examining how variability in inflation shapes the long-term growth rates of humans. Specifically, following the demographic buffering hypothesis we test whether increasing variance with positive autocorrelation in inflation environments negatively affects humans' capacity to buffer. Using high-resolution economic and demographic data from 76 countries over 1971-2024, we measured the structured demographic buffering as the sum of stochastic elasticities of growth rate to vital rates. To capture the effect of autocorrelated variability in vital rates on demographic buffering, we approximated the growth rate using stochastic sensitivities and elasticities. We find that increasing vital rates variance with positive autocorrelation in the inflation environment affects humans’ buffering capacity negatively. Our approach can be applied to study demographic buffering in a wide range of species with structured populations and against any possible driver of environmental variability, such as inflation. Therefore, this study makes a unique contribution to evolutionary and comparative demography.

Keywords: Biodemography and genetics, Comparative methods , Mathematical demography , Simulation

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