Why do pseudogenes evolve more rapidly than other genes?

Pseudogenes evolve more rapidly than other genes mainly because they are free from purifying selection. Purifying selection is a type of natural selection that removes deleterious alleles from a population, maintaining the integrity of functional genes. Since pseudogenes are often nonfunctional due to previous mutations that disrupted their coding ability, they no longer experience the same selective pressures that functional genes do. This lack of selective constraint allows for more variation to accumulate over time, enabling pseudogenes to diverge quickly from their ancestral sequences.

In contrast, functional genes are subject to purifying selection that conserves advantageous traits and eliminates harmful changes, resulting in slower evolutionary rates compared to pseudogenes. Thus, the rapid evolution of pseudogenes can provide insights into the underlying genetic mechanisms and evolutionary processes at play.