Scientists identify ecological factors that predict dark personality traits across 48 countries

Recent research published in the journal Evolution and Human Behavior offers new insights into how broad environmental conditions may shape “dark” personality traits on a national level. The study suggests that harsh or unpredictable ecological factors experienced during childhood, such as natural disasters or skewed sex ratios, are linked to higher average levels of traits like narcissism in adulthood. These findings indicate that forces largely outside of an individual’s control could play a key role in the development of antisocial personality profiles across different cultures.

The “Dark Triad” consists of three distinct but related personality traits: narcissism, Machiavellianism, and psychopathy. Individuals with high levels of narcissism often display grandiosity, entitlement, and a constant need for admiration. Machiavellianism is characterized by a cynical, manipulative approach to social interaction and a focus on self-interest over moral principles. Psychopathy involves high impulsivity, thrill-seeking behavior, and a lack of empathy or remorse for others.

While these traits are often viewed as undesirable, evolutionary perspectives suggest they may represent adaptive strategies in certain environments. Psychological research frequently focuses on immediate social causes for these traits, such as family upbringing or individual trauma. However, this new study aimed to broaden that lens by examining macro-level ecological factors that affect entire populations.

“There were several reasons to do this study,” explained Peter Jonason, a professor at Vizja University, creator of the Your Stylish Scientist YouTube Channel, and editor of Shining Light on the Dark Side of Personality: Measurement Properties and Theoretical Advances.

“First, there is limited understanding how ecological factors predict personality at all, let alone the Dark Triad. That is, most research focuses on personal, familial, or sociological predictors, but these are embedded in larger ecological systems. If the Dark Triad traits are mere pathologies of defunkt parenting or income inequality, one would not predict sensitivity to ecological factors in determining people’s adult Dark Triad scores let alone sex differences therein.”

“Second, most research on the Dark Triad traits focuses on individual-level variance but here we examined what you might call a culture of each trait and what might account for it. Third, and, less interestingly perhaps, the team happened to meet, get along, have the skills needed, and had access to the data to examine this.”

The researchers employed a theoretical framework known as life history theory to guide their investigation. This theory proposes that organisms, including humans, unconsciously adjust their reproductive and survival strategies based on the harshness and predictability of their environment. In dangerous or unstable environments, “faster” life strategies (characterized by greater risk-taking, short-term mating, and higher aggression) tend to be more advantageous for evolutionary fitness.

To test this idea, the researchers utilized existing personality data from 11,504 participants across 48 different countries. The data for these national averages were collected around 2016 using the “Dirty Dozen,” a widely used twelve-item questionnaire designed to briefly measure the three Dark Triad traits. The researchers then paired these personality scores with historical ecological data from the World Bank and other international databases.

They specifically examined ecological conditions during three developmental windows: early childhood (years 2000–2004), mid-childhood (years 2005–2009), and adolescence (years 2010–2015). The ecological indicators included population density, life expectancy (survival to age 65), and the operational sex ratio, which measures the balance of men to women in society. They also included data on the frequency of natural disasters, the prevalence of major infectious disease outbreaks, and levels of income inequality.

“When considering what makes people different from around the world, it is lazy to say ‘culture,'” Jonason told PsyPost. “Culture is a system that results from higher-order conditions like access to resources and ecological threats. If you want to understand why someone differs from you, you must consider more than just her/his immediate–and obvious–circumstances.”

The analysis used advanced statistical techniques known as spatial autoregressive models. These models allowed the researchers to not only test the direct associations within a country but also to account for “spillover” effects from neighboring nations. This approach recognizes that countries do not exist in isolation and may be influenced by the conditions and cultures of sharing borders.

The results indicated that different ecological factors were associated with distinct Dark Triad traits. Countries that had more male-biased sex ratios during the participants’ childhoods tended to have higher average levels of adult narcissism. The researchers suggest that an excess of males may intensify intrasexual competition, prompting men to adopt grander, more self-promoting behaviors to attract mates.

Conversely, a higher prevalence of infectious diseases during childhood and adolescence was associated with lower national levels of Machiavellianism and psychopathy. In environments with a high disease burden, strict adherence to social norms and greater group cohesion are often necessary for survival. In such contexts, manipulative or antisocial behaviors that disrupt group harmony might be less adaptive and therefore less common.

The study also found that ecological conditions might influence the magnitude of personality differences between men and women. Exposure to natural disasters during developmental years was consistently linked to larger sex differences across all three Dark Triad traits in adulthood. High-threat environments may cause men and women to adopt increasingly divergent survival and reproductive strategies, thereby widening the psychological gap between the sexes.

Furthermore, the research provided evidence for regional clustering of these personality profiles. Conditions in neighboring countries frequently predicted a focal country’s personality scores. For example, higher income inequality or natural disaster impact in bordering nations was associated with higher narcissism or Machiavellianism in the country being studied.

This suggests that dark personality traits may diffuse across borders. This could happen through mechanisms such as migration, shared regional economic challenges, or cultural transmission. The findings highlight the importance of considering regional contexts when studying national character.

“Do not assume that good parenting, safe schools, and successful social experiences are all that matter in determining who goes dark,” Jonason explained. “Larger factors, well beyond our control, have influence as well. By removing the human from the equation, we can better see how people are subject to forces well beyond their will, self-reports, and even situated in larger socioecological systems.”

As with all research, the study has some limitations that should be considered when interpreting these results. The personality data were largely derived from university students, who may not be fully representative of their national populations. Additionally, because the study relied on historical aggregate data, it cannot establish a definitive causal link between these ecological factors and individual personality development. It is possible that other unmeasured variables contribute to these associations.

Future research could aim to replicate these findings using more diverse and representative samples from the general population. The researchers also express an interest in investigating the specific psychological and cognitive mechanisms that might link broad environmental conditions to individual differences in motives and morals. Understanding these mechanisms could provide a clearer picture of how macro-level forces shape the human mind.

“We hope to pursue projects that try to understand the specific conditions that allow for not just personality, but also motives, morals, and mate preferences to be calibrated to local conditions providing more robust tests of not just cross-national differences, but, also, what are the cognitive mechanisms and perceptions that drive those differences,” Jonason said. “This is assuming we get some grant money to do so!”

“This is a study attempting to understand how lived experiences in people’s mileu can correlate with their personality and sex differences therein. This is an important step forward because while manipulating the conditions in people’s lives is nearly impossible, we can get a strong glimpse of how conditions in people’s generalized past can cause adaptive responses to help them solve important tasks like securing status and mates–two motivations highly valued by those high in the Dark Triad traits.”

The study, “Towards an ecological model of the dark triad traits,” was authored by Peter K. Jonason, Dritjon Gruda, and Mark van Vugt.