be avoided at all costs. Such views were naturally coupled to the pressing political and economic questions of the time. Spencer clearly thought society's evolution brought about a racial hierarchy with Caucasians at the top and Africans at the bottom. This notion is deeply linked to the colonial projects European powers were pursuing at the time, and the idea of European superiority used paternalistically to justify those projects. The influential German zoologist Ernst Haeckel even wrote that ‘natural men are closer to the higher vertebrates than highly civilized Europeans’, including not just a racial hierarchy but a civilizational one. Likewise, Spencer's evolutionary argument advanced a theory of statehood: “until spontaneously fulfilled a public want should not be fulfilled at all” sums up Spencer's notion about limited government and the free operation of market forces. This is not to suggest that stagism was useless or entirely motivated by colonialism and racism. Stagist theories were first proposed in contexts where competing epistemologies were largely static views of the world. Hence “progress” had in some sense to be invented, conceptually: the idea that human society would move through stages was a triumphant invention. Moreover, stages were not always static entities. In Buffon's theories, for example, it was possible to regress between stages, and physiological changes were species' reversibly adapting to their environment rather than irreversibly transforming. In addition to progressivism, economic analyses influenced classical social evolutionism. Adam Smith (1723–1790), who held a deeply evolutionary view of human society, identified the growth of freedom as the driving force in a process of stadial societal development. According to him, all societies pass successively through four stages: the earliest humans lived as hunter-gatherers, followed by pastoralists and nomads, after which society evolved to agriculturalists and ultimately reached the stage of commerce. With the strong emphasis on specialisation and the increased profits stemming from a division of labour, Smith's thinking also exerted some direct influence on Darwin himself. Both in Darwin's theory of the evolution of species and in Smith's accounts of political economy, competition between selfishly functioning units plays an important and even dominating rôle. Similarly occupied with economic concerns as Smith, Thomas R. Malthus (1766–1834) warned that given the strength of the sex drive inherent in all animals, Malthus argued, populations tend to grow geometrically, and population growth is only checked by the limitations of economic growth, which, if there would be growth at all,