Catagenesis is a somewhat archaic term from evolutionary biology referring to evolutionary directions that were considered "retrogressive."
It was a term used in contrast to anagenesis, which in present usage denotes the evolution of a single population into a new form without branching lines of descent.
The earliest written reference to catagenesis comes from Edward Drinker Cope,[1] in his article, On Catagenesis, published in The American Naturalist in 1884.
In this article, he defines the "primitive energy", which evolution through time has specialized.
He defines catagenesis as a return to the "primitive energy".