Selection and adaptation in human migration.

This article reviews the ways migration shapes human biology. This includes the physiological and genetic, but also socio-cultural aspects such as organization, behavior, and culture. Across disciplines I highlight the multiple levels of cultural and genetic selection whereby individuals and groups adapt to pressures along a migration timeline: the origin, transit, and destination. Generally, the evidence suggests that selective pressures and adaptations occur at the individual, family, and community levels. Consequently, across levels there are negotiations, interactions, and feedbacks that shape migration outcomes and the trajectory of evolutionary change. The rise and persistence of migration-relevant adaptations emerges as a central question, including the maintenance of cumulative culture adaptations, the persistence of "cultures of migration," as well as the individual-level physiological and cognitive adaptations applied to successful transit and settlement in novel environments.

Effects of human variation on foot and ankle pain in rural Madagascar.

OBJECTIVES: Foot and ankle dysfunction in barefoot/minimally shod populations remains understudied. Although factors affecting musculoskeletal pain in Western populations are well-studied, little is known about how types of work, gender, and body shape influence bone and joint health in non-Western and minimally shod communities. This study examines the effect of human variation on locomotor disability in an agrarian community in Madagascar. MATERIALS AND METHODS: Foot measurements were collected along with height, weight, age, and self-report data on daily activity and foot and ankle pain from 41 male and 48 female adults. A short form revised foot function index (FFI-R), that measures functional disability related to foot pain, was calculated. Raw and normalized foot measurements were compared by gender and used in a multiple linear regression model to determine predictors of FFI-R. RESULTS: Compared to men, women reported higher FFI-R scores (p = 0.014), spent more time on their feet (p = 0.019), and had higher BMIs (p = 0.0001). For their weight, women had significantly smaller and narrower feet than men. Bimalleolar breadth (p = 0.0005) and foot length (p = 0.0223) standardized by height, time spent on feet (p = 0.0102), ankle circumference standardized by weight (p = 0.0316), and age (p = 0.0090) were significant predictors of FFI-R score. DISCUSSION: Our findings suggest that human variation in anatomical and behavioral patterns serve as significant explanations for increased foot and ankle pain in women in this non-Western rural population. Foot and ankle pain were prevalent at similar levels to those in industrialized populations, indicating that research should continue to examine its effect on similar barefoot/minimally shod communities.

The Ratón Pérez collection: Modern deciduous human teeth at the Centro Nacional de Investigación sobre la Evolución Humana (Burgos, Spain).

OBJECTIVES: The aim of this report is to present the large deciduous tooth collection of identified children that is housed at the National Research Center on Human Evolution (CENIEH) in Burgos, Spain. METHODS: Yearly, members of the Dental Anthropology Group of the CENIEH are in charge of collecting the teeth and registering all the relevant information from the donors at the time of collection. In compliance with Spanish Law 14/2007 of July 3, 2007, on Biomedical Research (BOE-A-2007-12945), all individuals are guaranteed anonymity and confidentiality. When the donor hands in the tooth, they fill out a Donor Information Form and sign the Informed Consent Form. At the same time, another person completes the data label for the transparent polyethylene zip lock bag where the tooth is temporarily stored. All teeth are then transferred to the CENIEH Restoration lab, where the specialists apply the same protocol as for the fossil remains. RESULTS: Although the sample is still growing, from the first collection campaign in 2014 to date it comprises 2977 teeth of children whose ages of tooth loss are between 2 and 15 years. Each tooth is associated with basic information of the individuals and their parents and grandparents (sex, date, and place of birth, ancestry, country of residence), as well as important data about early life history (pregnancy duration, breastfeeding, bottle-feeding) and other relevant information provided by the donors (such as if they are twins, dental loss, or dental extraction). CONCLUSIONS: Due to the scarcity of deciduous dental samples available, the Ratón Pérez collection represents a highly valuable sample for a wide range of disciplines such as forensic, dental, and anthropological fields among others.

Teaching practice in human genetics integrated into general education.

General education is an important part in higher education, which emphasizes the educational idea of integration of generality with specialty, and practices people-oriented education concept. However, there are some difficulties and puzzles in general education. Now the general education system with Chinese characteristics is needed to be established through practice and development. In this paper, we enumerate how to integrate knowledge of human genetics in practice of general education, teaching cases, and relevant analysis with concepts of general education. Using questions as "what are human beings?" as a leverage, we introduce teaching contents closely related to daily life. For example, we explain the past, present and future of human beings through contemporary evolutionary genomics teaching. In addition, we introduce problem-based deep thinking for students, thus integrating classical attributes of human beings into general education.

The first Seriatum study of growth by R. E. Scammon.

Richard E. Scammon's article, "The First Seriatim Study of Human Growth," provided one of the best-known visuals in the field of human biology. Scammon resurrected longitudinal height data of one child from Buffon's Histoire Naturelle, converted them to metric, and plotted these measurements as a function of age. The result was the first graph of one individual's growth curve from birth to 18 years of age. This image was subsequently reproduced in numerous texts on human growth and biology. Published in 1927, Scammon's article provides a snapshot of the state of growth research at the time and gives a (literal) picture of the future of human biology. The graph of the growth of one child symbolizes the importance of process and variation in biological anthropology.

Craniofacial Secular Change in Recent Mexican Migrants.

Research by economists suggests that recent Mexican migrants are better educated and have higher socioeconomic status (SES) than previous migrants. Because factors associated with higher SES and improved education can lead to positive secular changes in overall body form, secular changes in the craniofacial complex were analyzed within a recent migrant group from Mexico. The Mexican group represents individuals in the act of migration, not yet influenced by the American environment, and thus can serve as a starting point for future studies of secular change in this population group. The excavation of a historic Hispanic cemetery in Tucson, Arizona, also allows for a comparison between historic Hispanics and recent migrants to explore craniofacial trends over a broad time period, as both groups originate from Mexico. The present research addresses two main questions: (1) Are cranial secular changes evident in recent Mexican migrants? (2) Are historic Hispanics and recent Mexican migrants similar? By studying secular changes within a migrant population group, secular trends may be detected, which will be important for understanding the biological variation of the migrants themselves and will serve as a preliminary investigation of secular change within Mexican migrants. The comparison of a sample of recent Mexican migrants with a historic Hispanic sample, predominantly of Mexican origin, allows us to explore morphological similarities and differences between early and recent Mexicans within the United States. Vault and face size and a total of 82 craniofacial interlandmark distances were used to explore secular changes within the recent Mexican migrants (females, n = 38; males, n = 178) and to explore the morphological similarities between historic Hispanics (females, n = 54; males, n = 58) and recent migrants. Sexes were separated, and multivariate adaptive regression splines and basis splines (quadratic with one knot) were used to assess the direction and magnitude of secular trends for the recent Mexican migrants. Because dates of birth were unavailable for the historic sample, partial least squares discriminant analysis (PLS-DA) was used to evaluate morphological differences between historic and recent Mexican migrant samples. The data were separated into a training data set and a testing data set to ensure realistic results. Males had eight variables (four positive and four negative) and females had six variables (two positive and four negative) that demonstrated significant differences over time. In the PLS-DA, three components were identified as important in model creation and resulted in a classification accuracy of 87% when applied to a testing sample. The high classification accuracy demonstrates significant morphological differences between the two groups, with the historic Hispanic sample displaying overall larger craniofacial dimensions. While differences in cranial morphology are evident between historic Hispanics and recent Mexican migrants, relatively few positive and negative secular trends were detected within the recent migrant sample.

A mixed model for the relationship between climate and human cranial form.

OBJECTIVES: We expand upon a multivariate mixed model from quantitative genetics in order to estimate the magnitude of climate effects in a global sample of recent human crania. In humans, genetic distances are correlated with distances based on cranial form, suggesting that population structure influences both genetic and quantitative trait variation. Studies controlling for this structure have demonstrated significant underlying associations of cranial distances with ecological distances derived from climate variables. However, to assess the biological importance of an ecological predictor, estimates of effect size and uncertainty in the original units of measurement are clearly preferable to significance claims based on units of distance. Unfortunately, the magnitudes of ecological effects are difficult to obtain with distance-based methods, while models that produce estimates of effect size generally do not scale to high-dimensional data like cranial shape and form. METHODS: Using recent innovations that extend quantitative genetics mixed models to highly multivariate observations, we estimate morphological effects associated with a climate predictor for a subset of the Howells craniometric dataset. RESULTS: Several measurements, particularly those associated with cranial vault breadth, show a substantial linear association with climate, and the multivariate model incorporating a climate predictor is preferred in model comparison. CONCLUSIONS: Previous studies demonstrated the existence of a relationship between climate and cranial form. The mixed model quantifies this relationship concretely. Evolutionary questions that require population structure and phylogeny to be disentangled from potential drivers of selection may be particularly well addressed by mixed models. Am J Phys Anthropol 160:593-603, 2016. © 2015 Wiley Periodicals, Inc.

Technical note: A linear model for predicting δ13 Cprotein.

OBJECTIVE: Development of a model for the prediction of δ(13) Cprotein from δ(13) Ccollagen and Δ(13) Cap-co . Model-generated values could, in turn, serve as "consumer" inputs for multisource mixture modeling of paleodiet. METHODS: Linear regression analysis of previously published controlled diet data facilitated the development of a mathematical model for predicting δ(13) Cprotein (and an experimentally generated error term) from isotopic data routinely generated during the analysis of osseous remains (δ(13) Cco and Δ(13) Cap-co ). RESULTS: Regression analysis resulted in a two-term linear model (δ(13) Cprotein (%) = (0.78 × Î´(13) Cco ) - (0.58× Δ(13) Cap-co ) - 4.7), possessing a high R-value of 0.93 (r(2) = 0.86, P < 0.01), and experimentally generated error terms of ±1.9% for any predicted individual value of δ(13) Cprotein . This model was tested using isotopic data from Formative Period individuals from northern Chile's Atacama Desert. CONCLUSIONS: The model presented here appears to hold significant potential for the prediction of the carbon isotope signature of dietary protein using only such data as is routinely generated in the course of stable isotope analysis of human osseous remains. These predicted values are ideal for use in multisource mixture modeling of dietary protein source contribution.

Reconciling "stress" and "health" in physical anthropology: what can bioarchaeologists learn from the other subdisciplines?

The concepts of "stress" and "health" are foundational in physical anthropology as guidelines for interpreting human behavior and biocultural adaptation in the past and present. Though related, stress and health are not coterminous, and while the term "health" encompasses some aspects of "stress," health refers to a more holistic condition beyond just physiological disruption, and is of considerable significance in contributing to anthropologists' understanding of humanity's lived experiences. Bioarchaeological interpretations of human health generally are made from datasets consisting of skeletal markers of stress, markers that result from (chronic) physiological disruption (e.g., porotic hyperostosis; linear enamel hypoplasia). Non-specific indicators of stress may measure episodes of stress and indicate that infection, disease, or nutritional deficiencies were present in a population, but in assessing these markers, bioarchaeologists are not measuring "health" in the same way as are human biologists, medical anthropologists, or primatologists. Rather than continue to diverge on separate (albeit parallel) trajectories, bioarchaeologists are advised to pursue interlinkages with other subfields within physical anthropology toward bridging "stress" and "health." The papers in this special symposium set include bioarchaeologists, human biologists, molecular anthropologists, and primatologists whose research develops this link between the concepts of "stress" and "health," encouraging new avenues for bioarchaeologists to consider and reconsider health in past human populations.

Higher-Order Clicker Questions Engage Students and Prepare Them for Higher-Order Thinking Activities.

Previous research has shown that the use of clickers in the classroom enhances student engagement. However, few studies have investigated how the type of clicker question may influence learning outcomes. To explore this, we compared the effects of lower-order cognitive skill (LOCS) and higher-order cognitive skill (HOCS) clicker questions on later exam performance in a biology course. During class time, students were presented with clicker questions directly related to unit content. Half of the content units were taught with LOCS, the other half with HOCS. To ensure that type of content did not influence results, the cognitive level of the clicker questions was counterbalanced across two semesters. The exams included a mix of LOCS and HOCS for each content unit. We also investigated the possible moderating effects of student perceptions on the relationship between type of clicker question and exam performance using student surveys. We found that using HOCS clicker questions significantly affects student learning. Practice with HOCS clicker questions improved performance on LOCS exam questions but not on HOCS exam questions. Students ranked lecture with clickers as a preferred and most helpful teaching methodology. Overall, these results suggest that practice with HOCS questions is engaging and gives students practice recalling content to "solve" a problem, thereby encoding low-level information and preparing them for higher-order thinking activities.

Organ-On-A-Chip: An Emerging Research Platform.

In drug development, conventional preclinical and clinical testing stages rely on cell cultures and animal experiments, but these methods may fall short of fully representing human biology. To overcome this limitation, the emergence of organ-on-a-chip (OOC) technology has sparked interest as a transformative approach in drug testing research. By closely replicating human organ responses to external signals, OOC devices hold immense potential in revolutionizing drug efficacy and safety predictions. This review focuses on the advancements, applications, and prospects of OOC devices in drug testing. Based on the latest advances in the field of OOC systems and their clinical applications, this review reflects the effectiveness of OOC devices in replacing human volunteers in certain clinical studies. This review underscores the critical role of OOC technology in transforming drug testing methodologies.

Embracing complexity in biomaterials design.

Animate materials, man-made materials behaving like living systems, are attracting enormous interest across a range of sectors, from construction and transport industry to medicine. In this leading opinion article, we propose that embracing complexity in biomaterials design offers untapped opportunities to create biomaterials with innovative life-like properties that extend their capabilities and unleash new paradigms in medical treatment.

A growth area: A review of the value of clinical studies of child growth for palaeopathology.

Studies of living children demonstrate that early life stress impacts linear growth outcomes. Stresses affecting linear growth may also impact later life health outcomes, including increased cardiometabolic disease risk. Palaeopathologists also assess the growth of children recovered from bioarchaeological contexts. Early life stresses are inferred to affect linear growth outcomes, and measurements of skeletal linear dimensions alongside other bioarchaeological information may indicate the types of challenges faced by past groups. In clinical settings, the impacts of stress on growing children are typically measured by examining height. Palaeopathologists are limited to examining bone dimensions directly and must grapple with incomplete pictures of childhood experiences that may affect growth. Palaeopathologists may use clinical growth studies to inform observations among past children; however, there may be issues with this approach. Here, we review the relationship between contemporary and palaeopathological studies of child and adolescent growth. We identify approaches to help bridge the gap between palaeopathological and biomedical growth studies. We advocate for: the creation of bone-specific growth reference information using medical imaging and greater examination of limb proportions; the inclusion of children from different global regions and life circumstances in contemporary bone growth studies; and greater collaboration and dialogue between palaeopathologists and clinicians as new studies are designed to assess linear growth past and present. We advocate for building stronger bridges between these fields to improve interpretations of growth patterns across human history and to potentially improve interventions for children living and growing today.

Germline burden of rare damaging variants negatively affects human healthspan and lifespan.

Heritability of human lifespan is 23-33% as evident from twin studies. Genome-wide association studies explored this question by linking particular alleles to lifespan traits. However, genetic variants identified so far can explain only a small fraction of lifespan heritability in humans. Here, we report that the burden of rarest protein-truncating variants (PTVs) in two large cohorts is negatively associated with human healthspan and lifespan, accounting for 0.4 and 1.3 years of their variability, respectively. In addition, longer-living individuals possess both fewer rarest PTVs and less damaging PTVs. We further estimated that somatic accumulation of PTVs accounts for only a small fraction of mortality and morbidity acceleration and hence is unlikely to be causal in aging. We conclude that rare damaging mutations, both inherited and accumulated throughout life, contribute to the aging process, and that burden of ultra-rare variants in combination with common alleles better explain apparent heritability of human lifespan.

Most living things undergo biological changes as they get older, a process that we generally refer to as aging. Despite being a widespread phenomenon, scientists do not fully understand why we age, though it appears that a combination of genetics and lifestyle factors, such as diet, play a role in influencing lifespan. Aging increases the risk of developing a wide range of diseases, including cancer, Alzheimer's disease and diabetes. As such, finding ways to slow the aging process would help to postpone the onset of illness and potentially improve health in old age. Genes are thought to be responsible for between one quarter and one third of the variation in human lifespans. The relationship between genes, aging and lifespan is complex and not well understood. One set of rare genetic changes that have been shown to have significant effects on diseases are called protein truncation variants (PTVs). PTVs cause damage by altering the production of certain proteins. There are many possible PTVs and people can be born with them or they can develop them in some cells later in life. The full influence of PTVs on aging is not known. Shindyapina, Zenin et al. have now studied observational data collected from two groups of over 40,000 people in the UK. Both groups recorded over 1,000 deaths, and the study examined the influence of PTVs on natural lifespan. The results show that each person is born with an average of six PTVs, which can vary in the impact that they have on aging. Having more, or more severe, PTVs could reduce life expectancy on average by 1.3 years. PTVs affect both total lifespan and healthy lifespan, the period of time lived prior to developing the first age-related disease. While PTVs that people are born with have a significant effect on aging, this study also showed that PTVs that are acquired due to spontaneous mutations through a person's life have much less of an impact. This is a key insight into the relationship between genes and aging. These discoveries could help in using genetics to anticipate future health, it also helps to identify some of the biological systems that have a role in aging. This could lead to new ways to delay the aging process and its effects on health.

A synthetic dataset primer for the biobehavioural sciences to promote reproducibility and hypothesis generation.

Open research data provide considerable scientific, societal, and economic benefits. However, disclosure risks can sometimes limit the sharing of open data, especially in datasets that include sensitive details or information from individuals with rare disorders. This article introduces the concept of synthetic datasets, which is an emerging method originally developed to permit the sharing of confidential census data. Synthetic datasets mimic real datasets by preserving their statistical properties and the relationships between variables. Importantly, this method also reduces disclosure risk to essentially nil as no record in the synthetic dataset represents a real individual. This practical guide with accompanying R script enables biobehavioural researchers to create synthetic datasets and assess their utility via the synthpop R package. By sharing synthetic datasets that mimic original datasets that could not otherwise be made open, researchers can ensure the reproducibility of their results and facilitate data exploration while maintaining participant privacy.

It is becoming increasingly common for scientists to share their data with other researchers. This makes it possible to independently verify reported results, which increases trust in research. Sometimes it is not possible to share certain datasets because they include sensitive information about individuals. In psychology and medicine, scientists have tried to remove identifying information from datasets before sharing them by, for example, adding minor artificial errors. But, even when researchers take these steps, it may still be possible to identify individuals, and the introduction of artificial errors can make it harder to verify the original results. One potential alternative to sharing sensitive data is to create 'synthetic datasets'. Synthetic datasets mimic original datasets by maintaining the statistical properties of the data but without matching the original recorded values. Synthetic datasets are already being used, for example, to share confidential census data. However, this approach is rarely used in other areas of research. Now, Daniel S. Quintana demonstrates how synthetic datasets can be used in psychology and medicine. Three different datasets were studied to ensure that synthetic datasets performed well regardless of the type or size of the data. Quintana evaluated freely available software that could generate synthetic versions of these different datasets, which essentially removed any identifying information. The results obtained by analysing the synthetic datasets closely mimicked the original results. These tools could allow researchers to verify each other's results more easily without jeopardizing the privacy of participants. This could encourage more collaboration, stimulate ideas for future research, and increase data sharing between research groups.

MEIS-mediated suppression of human prostate cancer growth and metastasis through HOXB13-dependent regulation of proteoglycans.

The molecular roles of HOX transcriptional activity in human prostate epithelial cells remain unclear, impeding the implementation of new treatment strategies for cancer prevention and therapy. MEIS proteins are transcription factors that bind and direct HOX protein activity. MEIS proteins are putative tumor suppressors that are frequently silenced in aggressive forms of prostate cancer. Here we show that MEIS1 expression is sufficient to decrease proliferation and metastasis of prostate cancer cells in vitro and in vivo murine xenograft models. HOXB13 deletion demonstrates that the tumor-suppressive activity of MEIS1 is dependent on HOXB13. Integration of ChIP-seq and RNA-seq data revealed direct and HOXB13-dependent regulation of proteoglycans including decorin (DCN) as a mechanism of MEIS1-driven tumor suppression. These results define and underscore the importance of MEIS1-HOXB13 transcriptional regulation in suppressing prostate cancer progression and provide a mechanistic framework for the investigation of HOXB13 mutants and oncogenic cofactors when MEIS1/2 are silenced.

Decisions regarding the treatment of patients with early-stage prostate cancer are often based on the risk that the cancer could grow and spread quickly. However, it is not always straightforward to predict how the cancer will behave. Studies from 2017 and 2018 found that samples of less aggressive prostate cancer have higher levels of a group of proteins called MEIS proteins. MEIS proteins help control the production of numerous other proteins, which could affect the behavior of prostate cancer cells in many ways. VanOpstall et al. ­ including some of the researchers that performed the 2017 and 2018 studies ­ have investigated how MEIS proteins affect prostate cancer. When prostate cancer cells are implanted into mice, they result in tumors. VanOpstall et al. found that tumors that produced MEIS proteins grew more slowly. Next, MEIS proteins were extracted from the prostate cancer cells and were found to interact with another protein called HOXB13, which regulates the activity of numerous genes. When the cells were genetically modified to prevent HOXB13 being produced, the protective effect of MEIS proteins was lost. MEIS proteins work with HOXB13 to regulate the production of several other proteins, in particular a protein called Decorin that can suppress tumors. When MEIS proteins and HOXB13 are present, the cell produces more Decorin and the tumors grow more slowly and are less likely to spread. VanOpstall et al. found that blocking Decorin production rendered MEIS proteins less able to slow the spread of prostate cancer. These results suggest that MEIS proteins and HOXB13 are needed to stop tumors from growing and spreading, and some of this ability is by prompting production of Decorin. This study explains how MEIS proteins can reduce prostate cancer growth, providing greater confidence in using them to determine whether aggressive treatment is needed. A greater understanding of this pathway for tumor suppression could also provide an opportunity for developing anti-cancer drugs.

Searching for the genetic key to a long and healthy life.

A study of over 40,000 individuals suggests that carrying a small number of ultra-rare genetic variants is associated with a longer lifespan.

Moving the human biology program from face-to-face to online delivery mode in the time of COVID-19.

Following the COVID-19 lockdown, the BSc in Human Biology Program of the University of Nicosia switched from face-to-face to online delivery mode. Herein we describe how we identified and managed the challenges that arose to successfully complete the Semester.

Yolk-sac-derived macrophages progressively expand in the mouse kidney with age.

Renal macrophages represent a highly heterogeneous and specialized population of myeloid cells with mixed developmental origins from the yolk-sac and hematopoietic stem cells (HSC). They promote both injury and repair by regulating inflammation, angiogenesis, and tissue remodeling. Recent reports highlight differential roles for ontogenically distinct renal macrophage populations in disease. However, little is known about how these populations change over time in normal, uninjured kidneys. Prior reports demonstrated a high proportion of HSC-derived macrophages in the young adult kidney. Unexpectedly, using genetic fate-mapping and parabiosis studies, we found that yolk-sac-derived macrophages progressively expand in number with age and become a major contributor to the renal macrophage population in older mice. This chronological shift in macrophage composition involves local cellular proliferation and recruitment from circulating progenitors and may contribute to the distinct immune responses, limited reparative capacity, and increased disease susceptibility of kidneys in the elderly population.

Older people are more likely to develop kidney disease, which increases their risk of having other conditions such as a heart attack or stroke and, in some cases, can lead to their death. Older kidneys are less able to repair themselves after an injury, which may help explain why aging contributes to kidney disease. Another possibility is that older kidneys are more susceptible to excessive inflammation. Learning more about the processes that lead to kidney inflammation in older people might lead to better ways to prevent or treat their kidney disease. Immune cells called macrophages help protect the body from injury and disease. They do this by triggering inflammation, which aides healing. Too much inflammation can be harmful though, making macrophages a prime suspect in age-related kidney harm. Studying these immune cells in the kidney and how they change over the lifespan could help scientists to better understand age-related kidney disease. Now, Ide, Yahara et al. show that one type of macrophage is better at multiplying in older kidneys. In the experiments, mice were genetically engineered to make a fluorescent red protein in one kind of macrophage. This allowed Ide, Yahara et al. to track these immune cells as the mice aged. The experiments showed that this subgroup of cells is first produced when the mice are embryos. They stay in the mouse kidneys into adulthood, and are so prolific that, over time, they eventually become the most common macrophage in older kidneys. The fact that one type of embryonically derived macrophage takes over with age may explain the increased inflammation and reduced repair capacity seen in aging kidneys. More studies will help scientists to understand how these particular cells contribute to age-related changes in susceptibility to kidney disease.

Reader engagement with medical content on Wikipedia.

Articles on Wikipedia about health and medicine are maintained by WikiProject Medicine (WPM), and are widely used by health professionals, students and others. We have compared these articles, and reader engagement with them, to other articles on Wikipedia. We found that WPM articles are longer, possess a greater density of external links, and are visited more often than other articles on Wikipedia. Readers of WPM articles are more likely to hover over and view footnotes than other readers, but are less likely to visit the hyperlinked sources in these footnotes. Our findings suggest that WPM readers appear to use links to external sources to verify and authorize Wikipedia content, rather than to examine the sources themselves.