Whether climate change or volcanic activity contributed to the demographic replacement documented in the 2025 study — either by weakening the Checua population and making them more vulnerable to replacement, or by creating conditions that favored the establishment of new populations with different subsistence strategies — cannot be determined from the genetic data alone.

But environmental context is always relevant to understanding demographic change, and the Altiplano’s complex climate history provides potential mechanisms for the demographic transitions that the genetics documents.

The 2,000-Year-Before-Present Moment

The most dramatic finding in the 2025 study’s time series is the complete genetic turnover between the Checua period at 6,000 years before present and the Herrera period at 2,000 years before present.

This transition deserves additional attention because of what the timing implies.