Molecular biology is
the study of structure and interactions of cellular molecules (including that
of RNA, DNA and proteins) which undertake processes specific to living things. Through
the study of molecular behaviour, scientists can compare gene sequences within DNA
of one species of animal with another to determine their evolutionary
relationship. The presence of mutations in genes is shared across all living
things and can be traced back to an evolutionary relative. By comparing genetic
sequences, relatedness between two individuals can be determined from the level
of genetic diversity between them, as it displays when they last shared a
mutual ancestor. This is done by calculating when a mutation occurred from a
“molecular clock” lying within cellular molecules. As information is inherited
through genetic molecules from one generation to the next, it can be measured
from the rate at which it changes and then by calculating the time required for
these changes to occur.