Genetic drift

Genetic drift is the random change in the frequency of traits within a population over time, occurring purely by chance rather than through natural selection. Imagine a small group of people where some have red hair and others have brown hair—if redheads happen to have fewer children by coincidence, red hair could disappear from the population simply due to luck, not because it's less useful for survival. This random process is especially powerful in small populations and helps explain why populations can change genetically even when no outside forces like predators or disease are pushing them in a particular direction.