cultures as well as individuals could be subject to natural selection. While these theories involved evolution applied to social questions, except for Darwin's group selection the theories reviewed above did not advance a precise understanding of how Darwin's mechanism extended and applied to cultures beyond a vague appeal to competition. Ritchie's Darwinism and Politics (1889) breaks this trend, holding that “language and social institutions make it possible to transmit experience quite independently of the continuity of race.” Hence Ritchie saw cultural evolution as a process that could operate independently of and on different scales to the evolution of species, and gave it precise underpinnings: he was ‘extending its range’, in his own words, to ideas, cultures and institutions. Thorstein Veblen, around the same time, came to a similar insight: that humans evolve to their social environment, but their social environment in turn also evolves. Veblen's mechanism for human progress was the evolution of human intentionality: Veblen labelled men ‘a creature of habit’ and thought that habits were ‘mentally digested’ from those who influenced him. In short, as Hodgson and Knudsen point out, Veblen thinks: "the changing institutions in their turn make for a further selection of individuals endowed with the fittest temperament, and a further adaptation of individual temperament and habits to the changing environment through the formation of new institutions." Thus, Veblen represented an extension of Ritchie's theories, where evolution operates at multiple levels, to a sophisticated appreciation of how each level interacts with the other. This complexity notwithstanding, Boas and Benedict used sophisticated ethnography and more rigorous empirical methods to argue that Spencer, Tylor, and Morgan's theories were speculative and systematically misrepresented ethnographic data. Theories regarding "stages" of evolution were especially criticised as illusions. Additionally, they rejected the distinction between "primitive" and "civilized" (or "modern"), pointing out that so-called primitive contemporary societies have just as much history, and were just as evolved, as so-called civilized societies. They therefore argued that any attempt to use this theory to reconstruct the histories of non-literate (i.e. leaving no historical documents) peoples is entirely speculative and unscientific. They observed that the postulated progression, which typically ended with a stage of civilization identical to that of modern Europe, is ethnocentric. They also pointed out that the theory assumes that societies are clearly bounded and distinct, when in fact cultural traits and forms often cross social boundaries and diffuse among many different societies (and