Why did early anthropologists reject unilinear theories of cultural evolution?

Early anthropologists rejected unilinear theories of cultural evolution because these models were increasingly viewed as scientifically flawed, ethnocentric, and racist.31

The 19th-century unilinear approach incorrectly assumed that all human societies progressed along a single, predetermined ladder—typically from "savagery" to "civilization"—with Western society positioned at the pinnacle. Anthropologists, led by figures such as Franz Boas and the cultural particularism school, challenged these hierarchies on several grounds:12

• Empirical Evidence: Fieldwork demonstrated that cultures are unique and shaped by their own specific histories and local environments, rendering broad, universal stages of development untenable.341
• Cultural Diffusion: Researchers observed that societies constantly learn from one another, a process of acculturation that contradicts the idea of isolated, linear progression.1
• Ethical Rejection: The theory was criticized for justifying inequality by suggesting that some peoples were biologically or culturally "less evolved" than others.31

In response, anthropologists shifted toward cultural relativism, emphasizing that all cultures are equally capable of meeting the needs of their members.41