RETROGRADATION • DICTIONARY ONE.COM • Definition of Retrogradation

... from going there, because of his barbarism, and because that portion of the most advanced race on earth shrinks from contact with it. The fact, then, of his barbarism is sustained, fully,—by his normal condition in Africa; his condition of retrogradation in Jamaica and San Domingo, where the experiment of emancipation has proved a failure, where the relapse into barbarism is sure and irrevocable; and in this country, where common sense and public opinion and public law, both ...

— The Right of American Slavery • True Worthy Hoit

... and changes that do not necessarily constitute an advance. Probably in most cases the modified type will be neither more nor less heterogeneous than the original one. In some cases the habits of life adopted being simpler than before, a less heterogeneous structure will result: there will be a retrogradation. But it must now and then occur, that some division of a species, falling into circumstances which give it rather more complex experiences, and demand actions somewhat more involved, will have certain of its organs further differentiated in proportionately ...

— Essays on Education and Kindred Subjects - Everyman's Library • Herbert Spencer