Associations between Belief in Conspiracy Theories and the Maladaptive Personality Traits of the Personality Inventory for DSM-5

Conspiracy theories can be treated as both rational narratives of the world as well as outcomes of underlying maladaptive traits. Here, we examined associations between belief in conspiracy theories and individual differences in personality disorders. An Internet-based sample (N=259) completed measures of belief in conspiracy theories and the 25 facets of the Personality Inventory for DSM-5 (PID-5). Preliminary analyses showed no significant differences in belief in conspiracy theories across participant sex, ethnicity, and education. Regression analyses showed that the PID-5 facets of Unusual Beliefs and Experiences and, to a lesser extent, Suspiciousness, significantly predicted belief in conspiracy theories. These findings highlight a role for maladaptive personality traits in understanding belief in conspiracy theories, but require further investigation.

Evolution of lactase persistence: an example of human niche construction

Niche construction is the process by which organisms construct important components of their local environment in ways that introduce novel selection pressures. Lactase persistence is one of the clearest examples of niche construction in humans. Lactase is the enzyme responsible for the digestion of the milk sugar lactose and its production decreases after the weaning phase in most mammals, including most humans. Some humans, however, continue to produce lactase throughout adulthood, a trait known as lactase persistence. In European populations, a single mutation (−13910*T) explains the distribution of the phenotype, whereas several mutations are associated with it in Africa and the Middle East. Current estimates for the age of lactase persistence-associated alleles bracket those for the origins of animal domestication and the culturally transmitted practice of dairying. We report new data on the distribution of −13910*T and summarize genetic studies on the diversity of lactase persistence worldwide. We review relevant archaeological data and describe three simulation studies that have shed light on the evolution of this trait in Europe. These studies illustrate how genetic and archaeological information can be integrated to bring new insights to the origins and spread of lactase persistence. Finally, we discuss possible improvements to these models.