Research published in the online edition of Nature last Wednesday (Feb. 9th) has found evidence for the “devolution” of marine worms. That is to say that the worms descended from a more complex ancestor. It was once thought that these two species, Xenoturbellida and Acoelomorpha, were an evolutionary link between simple creatures like jellyfish and the rest of the animal kingdom, but this work suggests otherwise. The joint University College London and Université de Montréal team compared hundreds of genes and concluded:
The results show that the two groups constitute a newly classified phylum (a major division of life), which the authors name the ‘Xenacoelomorpha’. The xenacoelomorph phylum joins the three known phyla of deuterostomes: vertebrates (including humans), echinoderms (e.g. starfish) and hemichordates (acorn worms).
HT: Science Daily
This is a major discovery because it opens a gap in our evolutionary understanding and provides evidence for an unexpected decrease in complexity. David Ringland of the Boston Examiner asks the question, “Could humans be moving in the same direction?”