Complex sentence: The molecular clock (based on the molecular clock hypothesis (MCH)) is a technique in molecular biology to relate the divergence time of two species diverged to the number of molecular differences measured between the species' DNA sequences or proteins.
Split into simpler sentences: The molecular clock (based on the molecular clock hypothesis (MCH)) is a technique in genetics to date when two species diverged. Elapsed time is deduced by applying a time scale to the number of molecular differences measured between the species' DNA sequences or proteins.