Conformist Transmission

Conformist transmission is a frequency-dependent bias in cultural transmission in which individuals preferentially adopt the most common variant in their reference group, regardless of the variant's intrinsic merit or their personal experience. It is one of the three primary transmission biases identified by Boyd and Richerson (alongside prestige bias and content bias), and it has profound consequences for the speed and stability of cultural evolution.

The mechanism is simple: when individuals use the frequency of a trait as a heuristic for its value, rare variants are systematically disadvantaged and common variants are amplified. This creates a positive feedback loop that can drive rapid cultural fixation — the entire population adopting a single variant in a few generations — even when the variant is objectively inferior to alternatives. Conformist transmission is a mechanism of cultural conformity, but modeled as an evolutionary strategy rather than a psychological pressure.

The adaptive logic is information-theoretic: in uncertain environments, the behavior of the majority is a noisy but useful signal about which practices are locally adaptive. If most people farm wheat rather than millet, wheat is probably safer. But this heuristic fails when environments change rapidly (the majority may be tracking an outdated optimum) or when the cultural trait is maladaptive but entrenched (the majority persists in a harmful practice because everyone copies everyone else). Conformist transmission is thus a double-edged sword: it stabilizes useful traditions and it stabilizes harmful ones with equal mechanical efficiency.