A new insect species is discovered on an island. The species features are compared to mainland species to determine the most closely related species.
Genetic analysis is performed on a chitin gene of both the island species and its mainland relative. The gene in both species is 4,000 bases long, and there are 10 differences in the bases between the two species.
If the estimated mutation rate for this family of insects is 0.000001 per nucleotide per year, how long ago did the common ancestor of both species exist?