What do molecular clocks measure?
The molecular clock is a technique that uses the mutation rate of bio molecules to deduce the time when two or more life forms diverged.
It measures the number of changes and mutations which accumulate in the gene sequences of different species over a period of time. Nucleotide sequences (for DNA ) and amino acid sequences ( for proteins ) are used as bio molecular data for these calculations.
Based on the fact that genetic mutations although random, occur at relatively constant rate, evolutionary scientists use this information to deduce how species evolve and and determine when two species diverged on the evolutionary time line.
The molecular clock technique is an important tool in molecular systematics.
It is also useful to determine the correct scientific classification of organisms by deriving information from molecular genetics.
It is useful in the study of variations in selective forces.
It also facilitates establishing the dates of phylogenetic events including those not documented by fossils.