An inevitably aging world -- Analysis on the evolutionary pattern of age structure in 200 countries

TL;DR

This paper uses statistical physics to analyze age structure evolution across 200 countries over 70 years, revealing a universal aging trend driven by the life cycle that affects all continents.

Contribution

It introduces a macro-level, tensor-based analysis method to uncover universal population aging laws across diverse countries, surpassing traditional regional statistical approaches.

Findings

All continents are moving towards aging populations.

The aging trend is driven by the universal life cycle.

Even currently young regions will inevitably age.

Abstract

Ignoring the differences between countries, human reproductive and dispersal behaviors can be described by some standardized models, so whether there is a universal law of population growth hidden in the abundant and unstructured data from various countries remains unclear. The age-specific population data constitute a three-dimensional tensor containing more comprehensive information. The existing literature often describes the characteristics of global or regional population evolution by subregion aggregation and statistical analysis, which makes it challenging to identify the underlying rules by ignoring national or structural details. Statistical physics can be used to summarize the macro characteristics and evolution laws of complex systems based on the attributes and motions of masses of individuals by decomposing high-dimensional tensors. Specifically, it can be used to assess the evolution of age structure in various countries over the past approximately 70 years, rather than simply focusing on the regions where aging has become apparent. It provides a universal scheme for the growing elderly and working age populations, indicating that the demographics on all continents are inevitably moving towards an aging population, including the current "young" continents of Africa, and Asia, South America with a recent "demographic dividend". It is a force derived from the "life cycle", and most countries have been unable to avoid this universal evolutionary path in the foreseeable future.