coalescent theory

Coalescent theory is a way scientists study the genetic history of populations by tracing how gene variants (alleles) in current individuals share common ancestors. Imagine looking back in time to see where different genetic lines merge into a single ancestor—this "merging" point is called a coalescent event. The theory helps estimate how populations evolved, grew, or shrank over time, based on the genetic differences we observe today. It provides a model to understand the ancestral relationships among genes and how evolutionary processes shape genetic diversity.