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How can genetic drift allow less-fit traits to spread in small populations?

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Marble bust of Aristotle with a beard and draped robe, showing detailed facial features and wavy hair, set against a dark background. — Philosophy of biology Detail of a Roman copy (2nd century bce) of a Greek alabaster portrait bust of Aristotle, c. 325 bce; in the collection of the Roman National Museum.

In the context of the philosophy of biology and population genetics, genetic drift allows less-fit traits to spread in small populations because it is a process driven by pure chance rather than by the survival or reproductive value of an allele.12

In small, isolated populations, the gene pool is limited, making it highly susceptible to sampling error. Because the number of individuals reproducing is finite, the genetic makeup of one generation may not perfectly represent the previous one due to random accidents of sampling.1324

While natural selection typically favors traits that improve fitness, genetic drift can override these selective pressures in small groups. If, by chance, individuals carrying a less-fit trait happen to produce more offspring or are disproportionately represented in the next generation, the frequency of that trait can increase. Over several generations, this random fluctuation can lead to the trait becoming widespread or even "fixed" within the population, regardless of whether it is biologically unfavorable.124