Sociocultural evolution, sociocultural evolutionism or social evolution are theories of sociobiology and cultural evolution that describe how societies and culture change over time. Whereas sociocultural development traces processes that tend to increase the complexity of a society or culture, sociocultural evolution also considers process that can lead to decreases in complexity (degeneration) or that can produce variation or proliferation without any seemingly significant changes in complexity (cladogenesis). Sociocultural evolution is "the process by which structural reorganization is affected through time, eventually producing a form or structure which is qualitatively different from the ancestral form". Most of the 19th-century and some 20th-century approaches to socioculture aimed to provide models for the evolution of humankind as a whole, arguing that different societies have reached different stages of social development. The most comprehensive attempt to develop a general theory of social evolution centering on the development of sociocultural systems, the work of Talcott Parsons (1902–1979), operated on a scale which included a theory of world history. Another attempt, on a less systematic scale, originated from the 1970s with the world-systems approach of Immanuel Wallerstein (1930-2019) and his followers. More recent approaches focus on changes specific to individual societies and reject the idea that cultures differ primarily according to how far each one has moved along some presumed linear scale of social progress. Most modern archaeologists and cultural anthropologists work within the frameworks of neoevolutionism, sociobiology, and modernization theory. Introduction Anthropologists and sociologists often assume that human beings have natural social tendencies and that particular human social behaviours have non-genetic causes and dynamics (i.e. people learn them in a social environment and through social interaction). Societies exist in complex social environments (i.e. with natural resources and constraints) and adapt themselves to these environments. It is thus inevitable that all societies change. Specific theories of social or cultural evolution often attempt to explain differences between coeval societies by positing that different societies have reached different stages of development. Although such theories typically provide models for understanding the relationship between technologies, social structure or the values of a society, they vary as to the extent to which they describe specific mechanisms of variation and change. While the history of evolutionary thinking with regard to humans can be traced back at least to Aristotle and other Greek philosophers, early sociocultural evolution theoriesthe ideas of Auguste Comte (1798–1857), Herbert Spencer (1820–1903) and Lewis Henry Morgan (1818–1881) developed simultaneously