Continental drift and the use of albumin as an evolutionary clock

ACCORDING to the concept of proteins as evolutionary clocks 1 , change in amino acid sequence during evolution is primarily a time-dependent process. This process accounts for the correlation generally found between the amount of time that has elapsed since two species last shared a common ancestor and the degree to which the sequences of their proteins differ today. A body of data consistent with such a correlation is now available for many proteins and nucleic acids 2–9 . Although there is increasingly widespread agreement that such a correlation exists 10–12 it is difficult to ascertain how strong the correlation is because of uncertainties in the interpretation of the fossil record, particularly with regard to times of divergence of lineages.