How are neutral mutations useful for estimating how long two species have been evolving independently?

Neutral mutations occur at a relatively constant rate and are not subject to natural selection, making them useful for molecular clock analyses. By comparing the number of neutral mutations accumulated in the genomes of two species, scientists can estimate the divergence time since they last shared a common ancestor. This provides a timeline for how long the species have been evolving independently, allowing researchers to infer evolutionary history and relationships.