A single gene ’invented’ haemoglobin several times

The Platynereis dumerilii vascular system in three segments © Song et al. BMC Evolutionary Biology - Thanks to the marine worm Platynereis dumerilii , an animal whose genes have evolved very slowly, scientists from CNRS, Université de Paris and Sorbonne Université, in association with others at the University of Saint Petersburg and the University of Rio de Janeiro, have shown that while haemoglobin appeared independently in several species, it actually descends from a single gene transmitted to all by their last common ancestor. These findings were published on 29 December 2020 in BMC Evolutionary Biology . Having red blood is not peculiar to humans or mammals. This colour comes from haemoglobin, a complex protein specialized in transporting the oxygen found in the circulatory system of vertebrates, but also in annelids (a worm family whose most famous members are earthworms), molluscs (especially pond snails) and crustaceans (such as daphnia or 'water fleas'). It was thought that for haemoglobin to have appeared in such diverse species, it must have been 'invented' several times during evolution. But recent research has shown that all of these haemoglobins born 'independently' actually derive from a single ancestral gene.