About

I am an evolutionary anthropologist whose principal focus is contemporary humans. Combining anthropological, psychological, and biological theories and methods, I approach a variety of aspects of human behavior, experience, and health from an integrative perspective in which humans are viewed as both the products of complex evolutionary processes and the possessors of acquired cultural idea systems and behavioral patterns. When colleagues are being polite, they refer to my research interests as 'eclectic'. Labels applied to my work include evolutionary psychology, biological anthropology, and evolutionary medicine.

Research topics

• Political Science
• Sociology
• Psychology
• Social psychology
• Computer Science
• Law
• Criminology
• Business
• Internet privacy
• Advertising
• Marketing
• Accounting
• Demography

Selected publications

• Data (Shareable)

  OSF Preprints (OSF Preprints) · 2026-01-19

  otherSenior author
  Publisher

• Explaining the Decline of impal Marriage among the Karo: An Epidemiological Approach

  2026-01-19

  articleOpen access

  The Karo of North Sumatra, Indonesia, have long expressed a preference for matrilateral cross-cousin (impal) marriage, yet the practice has declined sharply over the past century. To identify the demographic and sociocultural factors underlying this change, we applied an epidemiological approach to cultural evolution, using a case-control design coupled with structural equation modeling (SEM). Ethnographic data from 176 married individuals across 62 villages were analyzed to assess the effects of demographic, alliance, religious, cosocialisation, and modernisation variables on the likelihood of impal marriage. The model fit was strong (CFI = 0.96, RMSEA = 0.04), revealing significant direct and indirect effects. Marrying an impal was positively associated with the number of marriageable impal and with arranged or strategically motivated unions but negatively associated with reported religious conflict between spouses. Indicators of modernisation such as schooling and infrastructure were non-significant. These results indicate that the decline of impal marriage reflects demographic contraction and the weakening of alliance-based strategies rather than a rejection of the cultural norm itself. Framed within an epidemiological model of cultural transmission, the findings demonstrate how social practices may fade when the ecological and demographic conditions sustaining them erode, even as their normative value persists.

  PublisherDOI

• An evolutionary approach to privacy and information-management psychology

  Evolutionary Human Sciences · 2026-01-01

  articleOpen accessSenior author

  Abstract Current debates concerning the use of digital technology often focus on privacy, yet privacy attitudes and behaviour are remarkably under-theorized, and relatively little empirical research has investigated privacy beyond the realm of digital communications. Building on evolutionary scholarship on information exchange, we outline a theoretical model in which cultural concepts of privacy reflect the workings of evolved psychological mechanisms that aim to regulate others’ access to fitness-relevant information towards adaptive ends. Results of two initial U.S. vignette studies distributed via Prolific ( n = 425, 120) support the core predictions of this model, suggesting that people may have implicit and unstated assumptions regarding how information spreads in social environments. Specifically, participants’ privacy evaluations were predicted by whether information was intentionally acquired, the extent to which information was transmitted, and an individual’s position in an information transfer event. Importantly, how information was acquired and the nature of its transmission constituted independent but interacting influences on privacy perceptions. Additionally, results suggest the location within shared social networks of the individual to whom information is transmitted is used as a proxy for the potential costs of dissemination.

  PublisherDOI

• Explaining the Decline of impal Marriage among the Karo: An Epidemiological Approach

  SocArXiv (OSF Preprints) · 2026-01-19

  preprintOpen accessSenior author

  The Karo of North Sumatra, Indonesia, have long expressed a preference for matrilateral cross-cousin (impal) marriage, yet the practice has declined sharply over the past century. To identify the demographic and sociocultural factors underlying this change, we applied an epidemiological approach to cultural evolution, using a case-control design coupled with structural equation modeling (SEM). Ethnographic data from 176 married individuals across 62 villages were analyzed to assess the effects of demographic, alliance, religious, cosocialisation, and modernisation variables on the likelihood of impal marriage. The model fit was strong (CFI = 0.96, RMSEA = 0.04), revealing significant direct and indirect effects. Marrying an impal was positively associated with the number of marriageable impal and with arranged or strategically motivated unions but negatively associated with reported religious conflict between spouses. Indicators of modernisation such as schooling and infrastructure were non-significant. These results indicate that the decline of impal marriage reflects demographic contraction and the weakening of alliance-based strategies rather than a rejection of the cultural norm itself. Framed within an epidemiological model of cultural transmission, the findings demonstrate how social practices may fade when the ecological and demographic conditions sustaining them erode, even as their normative value persists.

  Publisher

• Daniel Palma Alvarado (2023). Pacos. Policías Estado y sociedad en Chile (desde el siglo XIX hasta 1927)

  Claves Revista de Historia · 2025-07-21

  articleOpen access1st authorCorresponding
  PublisherOA PDFDOI

• The Peripatetic Hater: Predicting Movement Among Hate Subreddits

  Proceedings of the International AAAI Conference on Web and Social Media · 2025-06-07 · 1 citations

  articleOpen access

  Many online hate groups exist to disparage others based on race, gender identity, sex, or other characteristics. The accessibility of these communities allows users to join multiple types of hate groups (e.g., a racist community and a misogynistic community), raising the question of whether users who join additional types of hate communities could be further radicalized compared to users who stay in one type of hate group. However, little is known about the dynamics of joining multiple types of hate groups, nor the effect of these groups on peripatetic users. We develop a new method to classify hate subreddits and the identities they disparage, then apply it to understand better how users come to join different types of hate subreddits. The hate classification technique utilizes human-validated deep learning models to extract the protected identities attacked, if any, across 168 subreddits. We find distinct clusters of subreddits targeting various identities, such as racist subreddits, xenophobic subreddits, and transphobic subreddits. We show that when users become active in their first hate subreddit, they have a high likelihood of becoming active in additional hate subreddits of a different category. We also find that users who join additional hate subreddits, especially those of a different category develop a wider hate group lexicon. These results then lead us to train a classification model that, as we demonstrate, usefully predicts the hate categories in which users will become active based on post text replied to and written. The accuracy of this model may be partly driven by peripatetic users often using the language of hate subreddits they eventually join. Overall, these results highlight the unique risks associated with hate communities on a social media platform, as discussion of alternative targets of hate may lead users to target more protected identities.

  PublisherOA PDFDOI

• Of scents and cytokines: How olfactory and food aversions relate to nausea and immunomodulation in early pregnancy

  Evolution Medicine and Public Health · 2025-01-01 · 2 citations

  articleOpen access

  Background: During pregnancy, the maternal body undergoes extensive physiological adaptations to support embryonic growth, including whole-body remodeling, that may induce odor and food aversions, as well as nausea and vomiting. The biological mechanisms behind odor and food aversions, as well as nausea and vomiting in early pregnancy, remain largely unexplored. Our study investigated associations between these changes and cytokine profiles during pregnancy. Methodology: = 58) completed a structured questionnaire on pregnancy "morning sickness"-related symptoms and aversions. Maternal plasma cytokine levels were measured between 5 and 17 weeks' gestation. Results: About 64% of participants experienced odor or food aversions, primarily to tobacco smoke and meat; 67% reported nausea, and 66% experienced vomiting. Multivariable linear regression models revealed that odor aversions were associated with increased pro-inflammatory T-helper-cell type (Th) 1 composite cytokine levels. Women who found tobacco smoke aversive exhibited a shift toward Th1 immune responses, indicated by a higher Th1:Th2 ratio. Food aversions also showed a positive association with Th1 cytokine levels. A borderline positive association was noted between nausea and vomiting and the Th1:Th2 ratio. Conclusions: These findings are consistent with the hypothesis that gestational changes in olfactory and gustatory experience, and nausea and vomiting, reflect adaptive upregulation of behavioral prophylaxis in ways that could protect the fetus. If this elevated Th1:Th2 ratio and pro-inflammatory phenotype are part of the maternal and embryonic response to embryogenesis, the behavioral and biological markers that we explore may provide an accessible index of fetal development during early pregnancy.

  PublisherOA PDFDOI

• X under Musk’s leadership: Substantial hate and no reduction in inauthentic activity

  PLoS ONE · 2025-02-12 · 33 citations

  articleOpen accessCorresponding

  Numerous studies have reported an increase in hate speech on X (formerly Twitter) in the months immediately following Elon Musk's acquisition of the platform on October 27th, 2022; relatedly, despite Musk's pledge to "defeat the spam bots," a recent study reported no substantial change in the concentration of inauthentic accounts. However, it is not known whether any of these trends endured. We address this by examining material posted on X from the beginning of 2022 through June 2023, the period that includes Musk's full tenure as CEO. We find that the increase in hate speech just before Musk bought X persisted until at least May of 2023, with the weekly rate of hate speech being approximately 50% higher than the months preceding his purchase, although this increase cannot be directly attributed to any policy at X. The increase is seen across multiple dimensions of hate, including racism, homophobia, and transphobia. Moreover, there is a doubling of hate post "likes," indicating increased engagement with hate posts. In addition to measuring hate speech, we also measure the presence of inauthentic accounts on the platform; these accounts are often used in spam and malicious information campaigns. We find no reduction (and a possible increase) in activity by these users after Musk purchased X, which could point to further negative outcomes, such as the potential for scams, interference in elections, or harm to public health campaigns. Overall, the long-term increase in hate speech, and the prevalence of potentially inauthentic accounts, are concerning, as these factors can undermine safe and democratic online environments, and increase the risk of offline harms.

  PublisherDOI

• Estudios sobre el sistema penitenciario montevideano. Un análisis de José Irureta Goyena (1909-1917)

  Revista de Historia de las Prisiones · 2025-09-03

  articleOpen access1st authorCorresponding

  En el presente artículo me propongo examinar la visión del doctor José Irureta Goyena sobre el sistema penitenciario montevideano formuladas en un período clave de su transformación a comienzos del siglo XX. Para ello, se consideró una serie de informes desarrollados en su carácter de miembro del Consejo Penitenciario, exhumados del archivo en proceso de clasif icación existente en el Centro de Formación Penitenciaria (Instituto Nacional de Rehabilitación), y dos artículos publicados en 1909 y 1912. El estudio permite rescatar su interés por las prisiones, soslayado por su trayectoria como jurista, conocer su posicionamiento sobre el régimen carcelario y visibilizar su balance sobre el funcionamiento de los establecimientos existentes y en construcción en la capital uruguaya. El análisis recoge su valoración en torno al papel regenerador asignado al trabajo, la importancia de la clasificación de los internos y su rechazo a la promiscuidad que representaba un régimen en común que toleraba el nocivo contacto entre presos. En sentido contrario, es constatable la defensa de Irureta Goyena de la conservación del régimen celular como una pieza esencial en la disciplina carcelaria y en la conversión de sus reclusos.

  PublisherOA PDFDOI

• I see sick people: Beliefs about sensory detection of infectious disease are largely consistent across cultures

  Brain Behavior and Immunity · 2025-04-22 · 2 citations

  articleOpen access
  PublisherOA PDFDOI

Frequent coauthors

• Colin Holbrook

  University of California, Merced

  47 shared

• Adam Maxwell Sparks

  Film Independent

  29 shared

• Colin Holbrook

  21 shared

• Theodore Samore

  University of California, Los Angeles

  20 shared

• Aoi Naito

  Japan Society for the Promotion of Science

  19 shared

• Carlos Navarrete

  18 shared

• Katinka Quintelier

  14 shared

• Tatsuya Kameda

  Meiji Gakuin University

  12 shared

Labs

• Daniel M T Fessler LabPI