Immunological distance is a measure of the number of unit differences
between two species, for example, in comparing human and baboon antibodies,
the sequencing of amino acids in humans, gorillas, chimpanzees and other
primates. If there are differences in amino acids [1] and proteins then
there are corresponding differences in the DNA. [2]
Organisms with very similar biochemical composition are said to be more
closely related than those less similar. The degree of similarity between
species can be used to work out when divergence took place by measuring
against a time scale.
