The impact of socioeconomic and phenotypic traits on self-perception of ethnicity in Latin America

Effects of facial skin pigmentation on social judgments in a Mexican population

People quickly and involuntarily form impressions of others based on their facial physical attributes, which can modulate critical social interactions. Skin pigmentation is one of the most variable and conspicuous facial traits among human populations. Empirical evidence suggests that these variations reflect ancestral ecological selective pressures balancing cutaneous vitamin D synthesis with the protection of the dermis from ultraviolet radiation. Nevertheless, skin pigmentation may currently be subject to additional selective pressures. For instance, the colonial era in Central and South America developed a highly stratified society based on ethnic origins, and light skin pigmentation became associated with higher social status and deference. This association could have originated through historical social learning that promoted favorable social perceptions towards individuals with lighter skin color and unfavorable perceptions towards individuals with darker skin color, which could still be present in the perception of current populations. Facial skin pigmentation is also sexually dimorphic, with males tending to exhibit darker skin than females, a difference that could be driven by sexual selection. To explore whether social learning and sexual selection represent additional selective pressures on skin pigmentation, we tested how this facial trait influences fundamental social perceptions in a Mexican population (N = 700, 489 female). We sampled facial images of eight European American males with natural lighter facial skin and eight males from an indigenous pre-Columbian community from Mexico, the Me'Phaa, with natural darker facial skin. We produced stimuli from these images by varying the skin pigmentation while preserving the facial shape. Stimuli were rated on attractiveness, trustworthiness, perceived health, dominance, aggressiveness, and femininity/masculinity. We found that the natural light-skinned faces were perceived as more attractive, trustworthy, and healthy but less dominant than the natural dark faces. Furthermore, by varying the facial skin color in these original groups, we altered the perceptions of them, mainly their attractiveness. These results partially support the hypothesis that dark facial skin color may help males compete for mates. Also, the results strongly support the view that lighter facial skin color became associated with social benefits through social learning in this Mexican population. Our findings, when viewed through the lens of cultural evolution, align with previous research in social psychology and anthropology. They hold the potential to offer a comprehensive understanding of the origin of this social phenomenon of cultural transmission, which currently plays a role in the formation of racial attitudes, stereotyping, and racial inequality in Mexican and other Latin American populations.

Cameriere's open apices methodology for dental age estimation in children: a scoping review from a Latin American perspective

Dental age estimation (DAE) is key to establishing an individual's identity, and this is relevant in minors. A widely used method for DAE in children is Cameriere's open apices (CAM). Despite its wide dissemination, there are no clear reports of its use in Latin American populations. A scoping review was conducted using a search strategy in the PubMed/MEDLINE database, Web of Science, and a complementary manual search. Only papers using CAM or its regression equation models for evaluating Latin American populations were included. Ten studies published between 2007 and 2020 responded to the search objective. Brazil was the country with the most studies using CAM (7/10), and the University of Macerata (Italy) was the most declared affiliation (6/10). Seven studies used the original CAM formula in populations from Brazil and Peru, while the European formula (EuCAM) was applied in Mexico, Colombia, and Brazil. Although the method underestimated the age values with acceptable error margins, the correction factor substantially improved the predictive power of the method. Some limitations of the method are highlighted. CAM and its variants can be useful for validation in Latin American settings, but attention to population structures and terminologies is suggested for future research.