Daniel J Kruger

University of Michigan | U-M · Population Studies Center

Background Patients use medical cannabis for a wide array of illnesses and symptoms, and many substitute cannabis for pharmaceuticals. This substitution often occurs without physician oversight, raising patient safety concerns. We aimed to characterize substitution and doctor-patient communication patterns in Canada, where there is a mature market...

Two of the controversies besetting the field of life history theory in psychology (LHT-P) are (1) whether life history strategy (LHS) is most fruitfully conceptualized as a latent reflective factor, or as a formative, descriptive construct and (2) whether the instruments most commonly used to measure psychometric LHS adequately cover its components...

Background: Products containing delta-8-THC became widely available in most of the USA following the 2018 Farm Bill and by late 2020 were core products of hemp processing companies, especially where delta-9-THC use remained illegal or required medical authorization. Research on experiences with delta-8-THC is scarce, some state governments have pr...

The present study examines the changes in the type and frequency of beverage consumption of Genesee County, Michigan residents before and after the Flint water crisis (FWC). Employing Speak to Your Health! Community Survey data of adults (N=1,825) and random-effects longitudinal ordered logistic regression, we examined between the frequency of dail...

Background People report using cannabis as a substitute for prescription medications but may be doing so without the knowledge of their primary health care providers (PCPs). This lack of integration creates serious concerns, e.g., using cannabis to treat medical conditions that have established treatment options. Methods We conducted an anonymous,...

Purpose This study evaluates third-year dental medicine students' perceived competencies related to interprofessional collaborative practice (IPCP) after completing two exposure level experiences with students from other professions across a large academic health center. Methods Two cohorts of D3 dental medicine students (2018–2019 and 2019–2020)...

Introduction: Cannabis products containing delta-8-THC became widely available in most of the United States in late 2020 and rapidly became a significant source of revenue for hemp processing companies, especially in states where use of delta-9-THC remains illegal or requires professional authorization for medical use. Scientific research on the us...

Between 2014 to 2015, the city of Flint suffered from critically contaminated water that caused long-term adverse health effects for many of its residents. In 2017, the “Speak to Your Health!” Community Survey assessed various aspects of adult Flint residents’ health. In addition to the health-related assessments, there were also questions about re...

Published in 1815, Jane Austen’s Emma is one of the most popular and critically acclaimed English novels, but it features one of the least likeable of Austen’s heroines. At the beginning of the story, Emma Woodhouse is perceived by many readers in antagonistic terms but then undergoes a significant change. Using short character descriptions, we inv...

Introduction: Many health care providers would benefit from greater knowledge and awareness of medical cannabis, even if they choose not to integrate it into their medical practice. Unfortunately, health care providers generally report low knowledge of medical cannabis and cite this lack of knowledge as a barrier to making patient recommendations....

Given the rapid change in legal status and rise in cannabis use within the United States (U.S.), pharmacists will increasingly require competence in issues related to cannabis, especially for medical use. Pharmacy students and professionals in other health fields report low levels of cannabis knowledge, and medical cannabis users report that their...

Evolutionary psychologists propose that men’s conspicuous consumption facilitates mate attraction because it predicts resource investment in offspring. This article elaborates on the ultimate functions of men’s luxury displays based on Life History Theory. Three studies provide evidence for phenotypic mimicry, in which consumer product features mim...

Evolutionary definitions of altruism are only concerned with reproductive consequences and not motives or other psychological mechanisms, making them ideal for generalization to all forms of organisms. Hamilton's inclusive fitness theory explains altruistic behavior toward genetic relatives and has generated extensive empirical support. Trivers' th...

In this manuscript we describe an original study testing two competing hypotheses on intentions to rescue kin members in risky life-saving scenarios. The Cultural Hypothesis predicted an overall favoritism towards female kin compared to male kin, based on Atari et al.’s (2020) account of Qeirat and Ghayrah values more generally. Atari et al. (2020)...

Introduction: As more states allow for medical and nonregistered adult cannabis (i.e., marijuana) use, ensuring proper utilization should be a priority. Standardized labeling for foods and pharmaceutical drugs promotes consumer safety. This study investigated cannabis product labeling requirements in the United States. Materials and Methods: Resear...

Background Medical cannabis users report that their knowledge regarding cannabis is predominantly from their own personal experiences and the Internet. Objective We summarize and describe information found through Internet searches on medical cannabis in English language websites. Methods We used terms related to medical cannabis in the Google se...

Background The ongoing COVID-19 pandemic strains the medical system, limiting access to healthcare services. Many people use cannabis medically for chronic health conditions and as a substitute for other medications. As such, changes in cannabis access associated with COVID-19 may result in increased non-cannabis drug use. Methods We recruited N =...

This article applies a life history model to advance the evolutionary understanding of poetry that inspired nineteenth-century Swedish National Romanticism. We show that the characters featured in two of Erik Gustaf Geijer's poems, "The Viking" and "The Yeoman Farmer" (1811), display patterns of time perspective, mating effort, and parental investm...

We examined knowledge and practice of harm reduction strategies among people who use cannabis attending an annual public cannabis advocacy event. We also assessed the sources from which they glean information about cannabis. Participants ( n = 472) completed a brief survey assessing cannabis use, sources for information on cannabis, and harm reduct...

Purpose People consider food wasting behavior to be immoral. However, it is not clear whether people who consider food wasting behavior immoral waste less food. Building on previous qualitative studies, we conducted a large-sample quantitative study. We examined whether people who consider food wasting behavior immoral display food wasting behavior...

Background: The legal status of cannabis is rapidly evolving, outpacing systematic research and educational efforts. Aims: We investigated knowledge of cannabinoid content and dosages among frequent cannabis users. Methods: A brief survey was administered in April 2019 (N = 472) at a cannabis advocacy event in a state with legal medical and recreat...

Purpose To compare cannabis enthusiasts’ knowledge about cannabis risks and effectiveness in treating medical conditions with existing empirical evidence. Design A brief survey assessed cannabis use, information sources, and knowledge about risks and effectiveness. Setting A cannabis advocacy event in April 2019 in a state with legal medical and...

Life history theory (LHT) is a powerful explanatory framework in evolutionary science, integrating evolutionary, ecological, and socio-developmental perspectives. This study tests a life history framework for understanding variation in health-related behaviors in a modern society. Several life history indicators, including the Mini-K, Consideration...

While sleep research has focused primarily on aspects of the immediate physical environment and behavioral factors, a growing body of evidence suggests that broader social determinants may play an important role in sleep insufficiency. Yet public health education efforts for sleep largely address “sleep hygiene”, with an emphasis on information for...

This article applies a life history model to advance the evolutionary understanding of poetry that inspired nineteenth-century Swedish National Romanticism. We show that the characters featured in two of Erik Gustaf Geijer's poems, “The Viking” and “The Yeoman Farmer” (1811), display patterns of time perspective, mating effort, and parental investm...

Health-related research is broad, diverse, and fragmented theoretically, methodologically, and across disciplines. The understanding and improvement of human health would be accelerated by establishing a universal and deep framework integrating varied undertakings. This framework is evolutionary theory, the most powerful explanatory system in the l...

Prior research has shown that immigration law enforcement contributes to poor health outcomes-including reproductive health outcomes-among Latinos. Yet no prior research has examined how immigration enforcement might inhibit reproductive justice and limit individual's reproductive autonomy. We utilized data from an existing study that consisted of...

Four studies tested the existence of a social norm that one cannot simultaneously support two competing groups or teams. Our evolved coalitional psychology should be sensitive to individuals expressing mixed loyalties between rivals, as they represent substantial threats for defection. Study 1 manipulated confederate attire and demonstrated that pu...

Purpose: Food insecurity is a psychosocial stressor with deleterious effects on mental health. This study examined whether the local food environment moderates the association of individual food insecurity with poor mental health. Methods: Cross-sectional survey data were collected from adult residents of Flint, Michigan (n=291), in 2015. Multivari...

An evidence-based approach is needed to shape policies and practices regarding medical cannabis, thereby reducing harm and maximizing benefits to individuals and society. This project assesses attitudes towards and utilization of medical cannabis and the mainstream healthcare system among medical cannabis users. The research team administered brief...

Life history theory (LHT) is a powerful explanatory framework examining how developmental environments and life experiences shape allocations of effort to fitness-promoting domains in nested sets of trade-offs. Time orientation is a central psychological aspect of human life history variation, representing the degree to which behaviors are oriented...

Compared to women, men have a greater tendency to make conspicuous wealth displays and typically make greater contributions in non-somatic provisioning. Male resource displays often predict future paternal resource investments; however, some conspicuous displays may function as mating effort at the cost of investment potential. Men who tend to make...

Life history theory (LHT) is a powerful explanatory framework illustrating how ancestral and developmental environments shape allocations of effort to fitness-promoting domains in nested sets of trade-offs. LHT has previously informed basic research on evolved human psychology and behavior, and it also has great potential for application to practic...

Long-term residence in neighborhoods is thought to promote the development and maintenance of supportive relationships and trust. These strong social ties may, however, be limited in communities in post-industrial cities characterized by high levels of vacant properties. This study aimed to examine the relationship between neighborhood vacancy and...

Background and Purpose: Alcohol intoxication affects college students' eating patterns. Yet, little is known about dietary habits on the day after heavy alcohol consumption. The purpose of this study was to examine college students’ dietary choices during alcohol consumption and on the following day by gender and level of alcohol consumption (inclu...

Sports are an excellent venue for demonstrating evolutionary principles to audiences not familiar with academic research. Team sports and sports fandom feature dynamics of in-group loyalty and intergroup competition, influenced by our evolved coalitional psychology. We predicted that reactions to expressions signaling mutual team/group allegiance w...

Cell phones are useful tools with both practical and social benefits. However, using them in the context of face-to-face conversations may be problematic. We consider this behavior a form of ostracism and test its effects on the satisfaction of basic psychological needs for belonging, self-esteem, control, and meaningful existence. In Study 1 parti...

Introduction: This study characterizes the risk for unintended pregnancy among Latino men and women within a racially and ethnically diverse county in Michigan. Methods: Latino respondents aged 18 to 50 years who reported no intention to become pregnant in the next year and no contraception use were defined as "at risk" for unintended pregnancy....

Recent policing incidents have increased attention to relationships between community members and police. Academic research on attitudes toward police predominantly follows Tyler's process-based model of policing; examining the influence of sociodemographic factors on perceptions of procedural justice, whether or not police are fair and trustworthy...

Researchers studying interpersonal relationships often distinguish between “sexual infidelity” and “emotional infidelity.” Yet, it remains largely unclear whether and how individuals actually conceptualize these constructs in their own lives, and how men and women vary, if at all, in their definitions and understanding of different types of infidel...

Immigration raids exemplify the reach of immigration law enforcement into the lives of Latino community members, yet little research characterizes the health effects of these raids. We examined the health implications of an immigration raid that resulted in multiple arrests and deportations and occurred midway through a community survey of a Latino...

Konrad Lorenz (Zietschrift fur Tierpsychologie, 5, 234–409, 1943) proposed that pedomorphic characteristics (Kindchenschema) in infants and parental caregiving responses to these characteristics co-evolved in species with parental care. Previous research on Kindchenschema has generally utilized human infants and computer-generated or manipulated im...

Objectives After inadequate official response to community concerns over water quality following changes in Flint's municipal water supply, this study sought evidence for a relationship between water quality and community mental health. Design The Speak to Your Health Community Survey is a community-based participatory component of the health surv...

We examined the relationship between perceptions of household tap water quality and posttraumatic stress disorder (PTSD) symptoms during the Flint, Michigan, water crisis in 2015–2016. The Speak to Your Health Community Survey is a community-based participatory component of the health surveillance system in Genesee County, Michigan. Perceptions of...

Within the evolutionary framework of life history approach, procrastination—the purposive delay of an intended task—is seen as a life history trait characterized by prioritizing immediate benefits with little regard for long-term consequences under particular environmental conditions. The present study proposes that environment cues indicating a lo...

Background and Purpose: In April 2014, the municipal water source for Flint, Michigan was changed from Lake Huron to the Flint River. Although residents reported concerns about the quality of tap water and resulting health problems, officials insisted that the water was safe. This study examined relationships between self-reported tap water quality...

Cell phones are integral to the lives of contemporary university undergraduates in the USA. Observers documented cell phone use in public spaces within or immediately surrounding a large public university campus in the Midwestern USA. Individuals (N = 2013) were monitored from the time they entered a “waiting space,” either a line at a coffee shop...

Life history theory (LHT) is a powerful evolutionary framework for understanding physiological, psychological, and behavioral variation both between and within species. Researchers and theorists are increasingly integrating LHT into evolutionary psychology, as it provides a strong foundation for research across many topical areas. Human life histor...

Phantom cell phone experiences are instances when mobile cell phone users perceive ringing, vibrations, and/or visual stimuli indicating an incoming call or message, yet no call or message actually registers on the phone. As a human signal-detection issue, these experiences may be influenced by psychological factors. We hypothesize that phantom cel...

This article attends to recent discussions of validity in psychometric research on human life history strategy (LHS), provides a constructive critique of the extant literature, and describes strategies for improving construct validity. To place the psychometric study of human LHS on more solid ground, our review indicates that researchers should (a...

Empowerment-based strategies have become widely used method to address health inequities and promote social change. Few researchers, however, have tested theoretical models of empowerment, including multidimensional, higher-order models. We test empirically a multidimensional, higher-order model of psychological empowerment (PE), guided by Zimmerma...

Individuals exhibit differences in their life history strategies along a continuum that ranges from fast (involving investments in immediate rewards) to slow (involving long-term relationships and investments). Components of life history have been demonstrated to be more strongly correlated in individuals with faster life histories, a phenomenon te...

Community attitudes toward the police are of increasing concern to scholars and practitioners. Although it is widely accepted that perceptions of procedural justice are influential in shaping citizens’ attitudes toward police, prior studies have not considered its relationship to crime density. To address this gap, we examined the relationship betw...

Introduction: Little is known about the role of positive financial behaviors (behaviors that allow maintenance of financial stability with financial resources) in mitigating cost-related nonadherence (CRN) to health regimens. This study examined the relationships between positive financial behaviors, financial stress, and CRN. Methods: Data came...

Life History Theory is a powerful framework that can help promote understanding of variation in health-related behavioral patterns and why they vary consistent with environmental conditions. An organism's life history reflects tradeoffs made in the allocation of effort towards specific aspects of survival and reproduction across the lifespan. This...

Research on neighborhood factors that influence health and crime often use neighborhood measures of geographic areas such as census tracts, wards, and postal sectors. These administratively defined areas, however, may mask the heterogeneity of neighborhood influences. In response to calls for more specific measures, we tested the reliability and va...

This study investigated the role of present and future time perspectives, and their relationships with subjective norms and beliefs regarding violence, in predicting violent behaviors among urban middle school students in the Midwestern United States. Although present time perspective covaried with subjective norms and beliefs, each made a unique p...

Mobile cell phone users have reported experiencing ringing and/or vibrations associated with incoming calls and messages, only to find that no call or message had actually registered. We believe this phenomenon can be understood as a human signal detection issue, with potentially important influences from psychological attributes. We hypothesized t...