 All of these inferences have been challenged by recent cultural evolutionary theory. Cultural evolutionists agree that at the level of the population, cumulative evolution requires that fitness-enhancing cultural traits are preserved in the offspring generation. However, they deny that this requires faithful transmission between individuals. A formal model from Henrich and Boyd (2002) suggests that conformist bias can overcome the effects of error-prone learning to produce reliable inheritance at the population level. Conformist bias was defined, in section 2 above, as the tendency of individuals to adopt the most common representation in a population. Henrich and Boyd cite evidence that conformist bias is a real phenomenon (although again see Lewens 2015 for scepticism about the case for conformism). Henrich and Boyd’s theoretical model assumes that individuals are poor at inferring the representations of others. Even so, they argue that when we look to the population level, conformist bias helps to correct the effects of such errors, producing a population-wide distribution of representations in the offspring generation that is close to the population-wide distribution of representations in the parent generation. Henrich and Boyd explain the reason for this. In general, error-prone transmission has a tendency to produce a mixture of different representations. In a population that already contains several different representations at significant frequencies, the effect of error on a population-wide distribution of representations is therefore low. In a population in which one representation is common, the effects of error are much more significant. But if we add conformist bias, we increase the chances of a commonly held representation remaining commonly held in future generations, even with error-prone imitation.