societies as superior to "primitive" societies (one need only look to the impact of medical science on health and lifespan) he rejected theories of white supremacy; he supported the Out-of-Africa theory of human evolution and believed that all races and social classes were equal in talent. However, Ward did not think that evolutionary progress was inevitable and he feared the degeneration of societies and cultures, which he saw as very evident in the historical record. Ward also did not favor the radical reshaping of society as proposed by the supporters of the eugenics movement or by the followers of Karl Marx; like Comte, Ward believed that sociology was the most complex of the sciences and that true sociogenesis was impossible without considerable research and experimentation. Émile Durkheim, another of the "fathers" of sociology, developed a dichotomal view of social progress. His key concept was social solidarity, as he defined social evolution in terms of progressing from mechanical solidarity to organic solidarity. In mechanical solidarity, people are self-sufficient, there is little integration and thus there is the need for the use of force and repression to keep society together. In organic solidarity, people are much more integrated and interdependent and specialisation and cooperation are extensive. Progress from mechanical to organic solidarity is based firstly on population growth and increasing population density, secondly on increasing "morality density" (development of more complex social interactions) and thirdly on increasing specialisation in the workplace. To Durkheim, the most important factor in social progress is the division of labour. This was later used in the mid-1900s by the economist Ester Boserup (1910–1999) to attempt to discount some aspects of Malthusian theory. Ferdinand Tönnies (1855–1936) describes evolution as the development from informal society, where people have many liberties and there are few laws and obligations, to modern, formal rational society, dominated by traditions and laws, where people are restricted from acting as they wish. He also notes that there is a tendency to standardisation and unification, when all smaller societies are absorbed into a single, large, modern society. Thus Tönnies can be said to describe part of the process known today as globalization. Tönnies was also one of the first sociologists to claim that the evolution of society is not necessarily going in the right direction, that social progress is not perfect, and it can even be called a regression as the newer, more evolved societies are