Papers by Andrew Van Horn
Friendships are important for social support and mental health, yet social distancing during the ... more Friendships are important for social support and mental health, yet social distancing during the COVID-19 pandemic has limited people’s ability to interact with their friends during this time. In August 2020, we asked participants about their friendships during the pandemic as part of a larger longitudinal study. We found that younger people and people with higher subjective SES reported more negative effects on their friendships as a result of the pandemic, including feeling lonelier and less satisfied with their friends. We also found that feelings of stress, isolation, and guilt were associated with greater COVID-related social risk taking, such as being motivated to make new friends and visit friends in person. These results show that the pandemic is likely affecting friendships differently across demographic groups and suggest that the negative impacts of COVID-19 on friendships might motivate some COVID-related social risk taking in order to try to maintain friendships or buil...
Morphological characters such as sexual size dimorphism (SSD), residual testes weight (RTW) and s... more Morphological characters such as sexual size dimorphism (SSD), residual testes weight (RTW) and sperm midpiece volume (MPV) differ among species and between groups of species with similar mating systems. However, because species-specific intensities of pre- and post-copulatory, male-male competition are difficult to quantify and mating system categories are broad, hypotheses of sexual selection are difficult to test. We used principal components analysis (PCA) to reduce the dimensions of a morphological dataset and create a 2-dimensional morphospace. We analyzed a correlation matrix of data on RTW, MPV and three measures of SSD for 27 species. Species’ PC scores were plotted on a bivariate graph. The first two PCs accounted for 80.13% of variance in the dataset (48.48% and 31.65%, respectively). PC1 correlated with SSD traits, and PC2 with MPV and RTW. We calculated the area of the convex hull of species’ positions in morphospace and asked whether species c lustered more tightly by mating system or phylogeny. We then compared mean PC1 and mean PC2 values between mating systems using ANOVA. Species clustered more closely when grouped by mating system than when grouped by phylogeny and mean PC values differed between mating systems (p < 0.005). In post-hoc analysis, we separated polygyandrous species above the fourth quintile of PC1 from those below, which tightened clustering by both measures. These results suggest reproductive skew may be highest in strongly dimorphic, polygynandrous primates. Further, variation in the intensity of precopulatory competition is an important driver of phenotypic diversity in polygynandrous primates.
Journal of Physical Activity and Health
Background: Physical activity (PA) mitigated psychological distress during the initial weeks of t... more Background: Physical activity (PA) mitigated psychological distress during the initial weeks of the COVID-19 pandemic, yet not much is known about whether PA had effects on stress in subsequent months. We examined the relationship between change over time in COVID-related stress and self-reported change in PA between March and July 2020. Methods: Latent growth modeling was used to examine trajectories of change in pandemic-related stress and test their association with self-reported changes in PA in an international sample (n = 679). Results: The participants reported a reduction in pandemic-related stress between April and July of 2020. Significant linear (factor mean = −0.22) and quadratic (factor mean = 0.02) changes (Ps
Since the beginning of the COVID-19 pandemic, wearing protective facial masks has become a divisi... more Since the beginning of the COVID-19 pandemic, wearing protective facial masks has become a divisive issue, yet little is known about what drives differences in mask wearing across individuals. We surveyed 711 people around the world, asking about mask wearing and several other variables. We found that people who reported greater perceived risk of infection, stress, and those with greater consideration of future consequences reported wearing masks more often during in-person interactions. Participants who knew more people who had been infected and those who lived in postal codes with higher prevalence of COVID-19 perceived their risk of infection to be higher and reported greater pandemic-related stress. Perceived risk of infection and pandemic-related stress were higher overall in women and those reporting greater future-orientedness. Finally, participants who were more politically conservative reported lower perceived risk of becoming infected and lower stress than those who were m...
What explains differences in attitudes towards wearing protective face masks to limit the spread ... more What explains differences in attitudes towards wearing protective face masks to limit the spread of the SARS-CoV-2 virus? We investigated potential drivers of attitudes about mask wearing as part of a longitudinal study during the COVID-19 pandemic (N-participants = 711, N-countries = 36), focusing on people’s perceptions and feelings about seeing others in their local communities wearing masks. We found that both stress about COVID-19 and the local incidence rate of COVID-19 predicted these attitudes, but perceived risk of infection did not. We also found that older and politically right-leaning respondents tended to have more negative attitudes towards wearing masks, while those with more concern for future consequences have more positive attitudes. Individuals with a greater vulnerability to COVID-19 as well as those with increased disease-related stress reported inconsistent emotional reactions to seeing people wear masks in public. For example, older participants were likely to...
Personality and Individual Differences, 2022
Friendships provide social support and mental health benefits, yet the COVID-19 pandemic has limi... more Friendships provide social support and mental health benefits, yet the COVID-19 pandemic has limited interactions with friends. In August 2020, we asked participants (N = 634) about their friendships during the pandemic as part of a larger study. We found that younger people and people with higher subjective SES reported more negative effects on their friendships, including feeling more isolated and lonelier. We also found that stress, isolation, and guilt were associated with greater COVID-related social risk-taking, such as making and visiting new friends in person. Our results suggest the pandemic is affecting friendships differently across demographic groups and these negative effects might motivate social risk-taking.
Public Health Nutrition
ObjectiveThe present study evaluates the use of multiple correspondence analysis (MCA), a type of... more ObjectiveThe present study evaluates the use of multiple correspondence analysis (MCA), a type of exploratory factor analysis designed to reduce the dimensionality of large categorical data sets, in identifying behaviours associated with measures of overweight/obesity in Vanuatu, a rapidly modernizing Pacific Island country.DesignStarting with seventy-three true/false questions regarding a variety of behaviours, MCA identified twelve most significantly associated with modernization status and transformed the aggregate binary responses of participants to these twelve questions into a linear scale. Using this scale, individuals were separated into three modernization groups (tertiles) among which measures of body fat were compared and OR for overweight/obesity were computed.SettingVanuatu.ParticipantsNi-Vanuatu adults (n 810) aged 20–85 years.ResultsAmong individuals in the tertile characterized by positive responses to most of or all the twelve modernization questions, weight and mea...
Public Health Nutrition
ObjectiveThe present study evaluates the use of multiple correspondence analysis (MCA), a type of... more ObjectiveThe present study evaluates the use of multiple correspondence analysis (MCA), a type of exploratory factor analysis designed to reduce the dimensionality of large categorical data sets, in identifying behaviours associated with measures of overweight/obesity in Vanuatu, a rapidly modernizing Pacific Island country.DesignStarting with seventy-three true/false questions regarding a variety of behaviours, MCA identified twelve most significantly associated with modernization status and transformed the aggregate binary responses of participants to these twelve questions into a linear scale. Using this scale, individuals were separated into three modernization groups (tertiles) among which measures of body fat were compared and OR for overweight/obesity were computed.SettingVanuatu.ParticipantsNi-Vanuatu adults (n 810) aged 20–85 years.ResultsAmong individuals in the tertile characterized by positive responses to most of or all the twelve modernization questions, weight and mea...
Public Health Nutrition
ObjectiveThe present study evaluates the use of multiple correspondence analysis (MCA), a type of... more ObjectiveThe present study evaluates the use of multiple correspondence analysis (MCA), a type of exploratory factor analysis designed to reduce the dimensionality of large categorical data sets, in identifying behaviours associated with measures of overweight/obesity in Vanuatu, a rapidly modernizing Pacific Island country.DesignStarting with seventy-three true/false questions regarding a variety of behaviours, MCA identified twelve most significantly associated with modernization status and transformed the aggregate binary responses of participants to these twelve questions into a linear scale. Using this scale, individuals were separated into three modernization groups (tertiles) among which measures of body fat were compared and OR for overweight/obesity were computed.SettingVanuatu.ParticipantsNi-Vanuatu adults (n 810) aged 20–85 years.ResultsAmong individuals in the tertile characterized by positive responses to most of or all the twelve modernization questions, weight and mea...
Public Health Nutrition
ObjectiveThe present study evaluates the use of multiple correspondence analysis (MCA), a type of... more ObjectiveThe present study evaluates the use of multiple correspondence analysis (MCA), a type of exploratory factor analysis designed to reduce the dimensionality of large categorical data sets, in identifying behaviours associated with measures of overweight/obesity in Vanuatu, a rapidly modernizing Pacific Island country.DesignStarting with seventy-three true/false questions regarding a variety of behaviours, MCA identified twelve most significantly associated with modernization status and transformed the aggregate binary responses of participants to these twelve questions into a linear scale. Using this scale, individuals were separated into three modernization groups (tertiles) among which measures of body fat were compared and OR for overweight/obesity were computed.SettingVanuatu.ParticipantsNi-Vanuatu adults (n 810) aged 20–85 years.ResultsAmong individuals in the tertile characterized by positive responses to most of or all the twelve modernization questions, weight and mea...
American Journal of Physical Anthropology
Several studies demonstrate that human ovarian function is responsive to the energetic environmen... more Several studies demonstrate that human ovarian function is responsive to the energetic environment, which has led to the development of theoretical models that explain this phenomenon. Although many genes are involved in ovarian hormone production, the possibility that genetic polymorphism may affect ovarian response to energetic conditions has not been considered. Cytochrome P450c17α is an enzyme that produces androgen precursors used to make estrogens during ovarian steroidogenesis, and is encoded by the CYP17 gene. A functionally significant variant within the promoter region of CYP17 has been linked to variation in steroid production, and some evidence suggests that this polymorphism could alter transcription of CYP17 in an insulin-dependent manner. We tested the hypothesis that the CYP17 variant affected the relationship between anthropometric measurements and salivary estradiol in healthy women in the United States (n = 28). PCR-RLFP analysis was used to genotype women for the genetic variant, and estradiol was assayed from saliva by EIA. Moderated regression analysis of these preliminary data revealed a significant interaction between waist-to-hip ratio and CYP17 genotype (P = 0.004). Our study provides evidence that gene–environment interactions should be considered in future adaptive models for human ovarian function. Moreover, our results stand to illuminate possible associations between this genetic variant and reproductive disease. Am J Phys Anthropol, 2014.
American Journal of …, Jan 1, 2012
Conference Presentations by Andrew Van Horn
20-22 July 2013. Poster presented at the 2013
Morphological characters such as sexual size dimorphism (SSD), residual testes weight (RTW) and s... more Morphological characters such as sexual size dimorphism (SSD), residual testes weight (RTW) and sperm midpiece volume (MPV) differ among species and between groups of species with similar mating systems. However, because species-specific intensities of pre- and post-copulatory, male-male competition are difficult to quantify and mating system categories are broad, hypotheses of sexual selection are difficult to test. We used principal components analysis (PCA) to reduce the dimensions of a morphological dataset and create a 2-dimensional morphospace. We analyzed a correlation matrix of data on RTW, MPV and three measures of SSD for 27 species. Species’ PC scores were plotted on a bivariate graph. The first two PCs accounted for 80.13% of variance in the dataset (48.48% and 31.65%, respectively). PC1 correlated with SSD traits, and PC2 with MPV and RTW. We calculated the area of the convex hull of species’ positions in morphospace and asked whether species c lustered more tightly by mating system or phylogeny. We then compared mean PC1 and mean PC2 values between mating systems using ANOVA. Species clustered more closely when grouped by mating system than when grouped by phylogeny and mean PC values differed between mating systems (p < 0.005). In post-hoc analysis, we separated polygyandrous species above the fourth quintile of PC1 from those below, which tightened clustering by both measures. These results suggest reproductive skew may be highest in strongly dimorphic, polygynandrous primates. Further, variation in the intensity of precopulatory competition is an important driver of phenotypic diversity in polygynandrous primates.
Preeclampsia (PE) is a human specific disease affecting 5-10% of pregnancies. It is a leading cau... more Preeclampsia (PE) is a human specific disease affecting 5-10% of pregnancies. It is a leading cause of maternal/fetal
morbidity and mortality world-wide, in part because delivery of the fetus is the only cure. The etiology of the
disease is multifactorial and remains poorly understood but is clearly associated with placental dysfunction,
specifically the shallow invasion of cytotrophoblast (fetal) cells into the endometrium which compromises placental
blood supply. A genetic component of PE is suggested by several studies that report differential gene expression
levels in normal vs. preeclamptic placentae, and GWAS analyses identify multiple regions of the genome that could
be involved. My lab and collaborators have used a comparative transcriptome approach to investigate whether
placental genes differentially expressed in PE are evolving differently in humans relative to non-human primates.
We suggest that such genes may be among the most sensitive to dysregulation and therefore strong drivers of the
disease. HTRA1 is the only one of nearly 100 candidates that fits these criteria; it is under the strongest detectable
level of purifying selection in the human lineage. In the placenta HTRA1 expression is localized to the
cytotrophoblast and syncytiotrophoblast cells, HtrA1 levels are elevated in the sera of PE vs normal pregnancy
women, it can inhibit cell migration, modulate cell proliferation/apoptosis, and the protein has been implicated in
other vascular disorders. Thus, it appears to impact the most essential steps in successful placentation. An
evolutionary signature of lineage-specific, exceptionally strong, purifying selection may narrow the focus on
individual candidate genes in this and other disease states.
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Papers by Andrew Van Horn
Conference Presentations by Andrew Van Horn
morbidity and mortality world-wide, in part because delivery of the fetus is the only cure. The etiology of the
disease is multifactorial and remains poorly understood but is clearly associated with placental dysfunction,
specifically the shallow invasion of cytotrophoblast (fetal) cells into the endometrium which compromises placental
blood supply. A genetic component of PE is suggested by several studies that report differential gene expression
levels in normal vs. preeclamptic placentae, and GWAS analyses identify multiple regions of the genome that could
be involved. My lab and collaborators have used a comparative transcriptome approach to investigate whether
placental genes differentially expressed in PE are evolving differently in humans relative to non-human primates.
We suggest that such genes may be among the most sensitive to dysregulation and therefore strong drivers of the
disease. HTRA1 is the only one of nearly 100 candidates that fits these criteria; it is under the strongest detectable
level of purifying selection in the human lineage. In the placenta HTRA1 expression is localized to the
cytotrophoblast and syncytiotrophoblast cells, HtrA1 levels are elevated in the sera of PE vs normal pregnancy
women, it can inhibit cell migration, modulate cell proliferation/apoptosis, and the protein has been implicated in
other vascular disorders. Thus, it appears to impact the most essential steps in successful placentation. An
evolutionary signature of lineage-specific, exceptionally strong, purifying selection may narrow the focus on
individual candidate genes in this and other disease states.
morbidity and mortality world-wide, in part because delivery of the fetus is the only cure. The etiology of the
disease is multifactorial and remains poorly understood but is clearly associated with placental dysfunction,
specifically the shallow invasion of cytotrophoblast (fetal) cells into the endometrium which compromises placental
blood supply. A genetic component of PE is suggested by several studies that report differential gene expression
levels in normal vs. preeclamptic placentae, and GWAS analyses identify multiple regions of the genome that could
be involved. My lab and collaborators have used a comparative transcriptome approach to investigate whether
placental genes differentially expressed in PE are evolving differently in humans relative to non-human primates.
We suggest that such genes may be among the most sensitive to dysregulation and therefore strong drivers of the
disease. HTRA1 is the only one of nearly 100 candidates that fits these criteria; it is under the strongest detectable
level of purifying selection in the human lineage. In the placenta HTRA1 expression is localized to the
cytotrophoblast and syncytiotrophoblast cells, HtrA1 levels are elevated in the sera of PE vs normal pregnancy
women, it can inhibit cell migration, modulate cell proliferation/apoptosis, and the protein has been implicated in
other vascular disorders. Thus, it appears to impact the most essential steps in successful placentation. An
evolutionary signature of lineage-specific, exceptionally strong, purifying selection may narrow the focus on
individual candidate genes in this and other disease states.