Final answer:
Unilineal Evolutionism posits that societies progress linearly through stages ending in civilization, a theory promoted by figures such as Herbert Spencer within the flawed framework of Social Darwinism. These concepts, once used to justify social inequalities and colonialism, are no longer prominent in contemporary scientific thought, having been critiqued and largely replaced by more nuanced understandings of cultural development.
Step-by-step explanation:
Understanding Unilineal Evolutionism and Social Darwinism
Unilineal Evolutionism refers to the 19th-century anthropological theory that suggested societies progress through a series of stages in a fixed sequence from savagery to barbarism and ultimately to civilization. This theory was adapted by scholars like Herbert Spencer, who also coined the term "survival of the fittest" and is known for his contributions to Social Darwinism. Social Darwinism is a misguided application of evolutionary concepts to human society, which upheld social inequalities by suggesting that economic and social differences were the result of natural selection. Spencer, alongside other anthropologists like E.B. Tylor and Lewis H. Morgan, based their claims on biological differences, thus supporting colonialist attitudes and justifying racism and class distinctions.
Émile Durkheim, an early sociologist, built on Spencer's theory to explain social changes and the survival of societies over time. Meanwhile, critics like Franz Boas challenged the notion of unilineal cultural evolution by highlighting the unique pathways of cultural development and the importance of interactions among cultures. Despite initially gaining considerable traction, both theories have largely fallen out of favor within the scientific community due to their support of social inequalities and the disproven idea that human societies evolve in a strict linear pattern.