Final answer:
The method of dating that uses the rate of genetic differences accumulation between species is known as the molecular clock.
Step-by-step explanation:
A method of dating where genetic differences between species accumulate at a constant rate is called a molecular clock. This method uses DNA sequences to measure how long it has been since related species diverged from a common ancestor, assuming that mutations accumulate through time at a steady average rate for a given region of DNA. The concept of the molecular clock is valuable for understanding the continuity of species and their evolutionary history, as it allows the calculation of the rate of speciation of early organisms by comparing the genetic material and determining their periods of divergence.