Testing Theories about Ethnic Markers

Ethnic markers and the emergence of group-specific norms: an experiment

Visible markers are an important factor in social interactions. Some researchers have argued that one of their roles is to promote cooperation, but models designed to address this issue have yielded contradictory results. Here we present an experimental study of the effect of visible markers on the emergence of social norms where human subjects play a binary coordination game. Our results do not show different, marker-dependent behaviors. Instead, in practically all sessions participants achieved a global equilibrium disregarding the markers. Our findings suggest that simple markers may have a limited role in promoting the emergence of group-dependent social norms and call for further research investigating the role of markers in more sophisticated social settings.

Ethnic markers and the emergence of group-specific norms

Observable social traits determine how we interact meaningfully in society even in our globalized world. While a popular hypothesis states that observable traits may help promote cooperation, the alternative explanation that they facilitate coordination has gained ground in recent years. Here we explore this possibility and present a model that investigates the role of ethnic markers in coordination games. In particular, we aim to test the role of reinforcement learning as the microscopic mechanism used by the agents to update their strategies in the game. For a wide range of parameters, we observe the emergence of a collective equilibrium in which markers play an assorting role. However, if individuals are too conformist or too greedy, markers fail to shape social interactions. These results extend and complement previous work focused on agent imitation and show that reinforcement learning is a good candidate to explain many instances where ethnic markers influence coordination.

Language as a marker of ethnic identity among the Yucatec Maya

Most human variation is structured around symbolically marked cultural ('ethnic') groups that require common codes of communication. Consequently, many have hypothesised that using others' linguistic competences as markers of their descent is part of an evolved human psychology. However, there is also evidence that the use of language as ethnic markers is not universally applied, but context specific. We explore the tension between these views by studying responses to bilingualism among 121 adults living in Mayan communities undergoing rapid socioeconomic changes involving increased contact with Spanish-speaking towns. We show that, although competences in Mayan were strongly tied to perceiving others as having a Mayan ethnic identity, ethnolinguistic category membership was not seen as stable through life, vertically transmitted, nor regarded as incompatible with competences in Spanish. Moreover, we find variation in how people reasoned about ethnolinguistic identities depending on their own linguistic repertoires. Our work suggests that, while there may be an evolved predisposition to use language as a signal of group identity, our developmental plasticity allows us to respond adaptively to social information around us, leading to psychological and behavioural variation within and across populations. How people reason about others based on their linguistic profiles will affect the payoffs of acquiring different languages and ultimately the long-term sustainability of linguistic diversity.

Phonetic change in an Antarctic winter

An acoustic analysis was made of the speech characteristics of individuals recorded before and during a prolonged stay in Antarctica. A computational model was used to predict the expected changes due to close contact and isolation, which were then compared with the actual recorded productions. The individuals were found to develop the first stages of a common accent in Antarctica whose phonetic characteristics were in some respects predicted by the computational model. These findings suggest that the phonetic attributes of a spoken accent in its initial stages emerge through interactions between individuals causing speech production to be incrementally updated.

Evolutionary Dynamics of Homophily and Heterophily

Most social interactions do not take place at random. In many situations, individuals choose their interaction partners on the basis of phenotypic cues. When this happens, individuals are often homophilic, that is, they tend to interact with individuals that are similar to them. Here we investigate the joint evolution of phenotypic cues and cue-dependent interaction strategies. By a combination of individual-based simulations and analytical arguments, we show that homophily evolves less easily than earlier studies suggest. The evolutionary interplay of cues and cue-based behaviour is intricate and has many interesting facets. For example, an interaction strategy like heterophily may stably persist in the population even if it is selected against in association with any particular cue. Homophily persisted for extensive periods of time just in those simulations where homophilic interactions provide a lower (rather than a higher) payoff than heterophilic interactions. Our results indicate that even the simplest cue-based social interactions can have rich dynamics and a surprising diversity of evolutionary outcomes.