A hierarchical bayesian analysis of parasite prevalence and sociocultural outcomes: The role of structural racism and sanitation infrastructure

Abstract

Objectives: We conduct a revaluation of the Thornhill and Fincher research project on parasites using finelyresolved geographic data on parasite prevalence, individual-level sociocultural data, and multilevel Bayesian modeling. In contrast to the evolutionary psychological mechanisms linking parasites to human behavior and cultural characteristics proposed by Thornhill and Fincher, we offer an alternative hypothesis that structural racism and differential access to sanitation systems drive both variation in parasite prevalence and differential behaviors and cultural characteristics.Methods: We adopt a Bayesian framework to estimate parasite prevalence rates in 51 districts in eight Latin American countries using the disease status of 170,220 individuals tested for infection with the intestinal roundworm Ascaris lumbricoides (H€ urlimann et al., [2011]: PLoS Negl Trop Dis 5:e1404). We then use district-level estimates of parasite prevalence and individual-level social data from 5,558 individuals in the same 51 districts (Latinobarometro, 2008) to assess claims of causal associations between parasite prevalence and sociocultural characteristics.Results: We find, contrary to Thornhill and Fincher, that parasite prevalence is positively associated with preferences for democracy, negatively associated with preferences for collectivism, and not associated with violent crime rates or gender inequality. A positive association between parasite prevalence and religiosity, as in Fincher and Thornhill (2012: Behav Brain Sci 35:61-79), and a negative association between parasite prevalence and achieved education, as predicted by Eppig et al. (2010: Proc R S B: Biol Sci 277:3801-3808), become negative and unreliable when reasonable controls are included in the model. We find support for all predictions derived from our hypothesis linking structural racism to both parasite prevalence and cultural outcomes.Conclusions: We conclude that best practices in biocultural modeling require examining more than one hypothesis, retaining individual-level data and its associated variance whenever possible, and adopting multilevel techniques suited to the structuring of the data. Am. J. Hum. Biol. 00:000-000, 2015.

Parasites and politics: why cross-cultural studies must control for relatedness, proximity and covariation

“…This means that a significant link between any one cultural trait and parasite load will tend to produce statistically significant correlations between parasite load and other cultural traits. Analysing variables separately, or in small groups of related variables, could lead to the impression that parasite load influences many different aspects of culture [59]. In particular, we find that language diversity, sociosexuality, democracy and authoritarianism have no significant correlation with parasite load, above and beyond that explained by their covariation with other cultural traits that scale with parasite load (traditionalism, religiosity, collectivism).…”

“…The influence of parasite load on cultural evolution has been widely debated, and published studies have been criticized on methodological, empirical and practical grounds [43,49,59,60]. Our purpose here is to consider one specific criticism, which is that cross-cultural correlations showing a link between parasite load and cultural traits may be statistical artefacts [49].…”

A Multi-Level Bayesian Analysis of Racial Bias in Police Shootings at the County-Level in the United States, 2011–2014

“…Ecological regression on county-level characteristics is plagued by difficulties theoretically [ 39 , 51 ]; issues with data quality make it even harder to use county-level data. In the analysis of county-level predictors of racial bias in police shootings conducted in this paper, some of the data were low quality.…”

What Role Does Pathogen-Avoidance Psychology Play in Pandemics?

“…Even if this last account is correct, the precise information extracted from the environment to estimate parasite stress is unclear. Moreover, focusing on patterns at the level of national averages obscures processes that can generate very different patterns at the level of individuals [80,81]. For COVID-19 research to avoid the pitfalls that characterize parasite stress work, clear mechanistic accounts of how and why the pandemic affects behavior will be important.…”