Assessing interdependence between self and specific others has a rich history in psychological sc... more Assessing interdependence between self and specific others has a rich history in psychological science. Here, we report a novel scale to measure Shared Fate. Studies 1 and 2 (N1 = 198, N2 = 216) show that the Shared Fate scale has two factors assessing perceived shared fate and emotional shared fate with a target, has good reliability (Cronbach’s alpha = 0.81 to 0.91; McDonald’s omega = 0.89 to 0.96), and predicts participants’ willingness to help interdependent others. Studies 3 and 4 (N3 = 695, N4 = 629) indicate that the Shared Fate scale has good discriminant, convergent, concurrent, and predictive validity as well as test-retest reliability across a 14-day period. Taken together, our results suggest that Shared Fate scale is a useful instrument for work on cooperation, interdependence, and social behavior. However, there are still many open questions about the cognitive architecture underlying perceptions of shared fate and how shared fate interacts with genetic relatedness and other sources of fitness interdependence.
Despite continued transmission of SARS-CoV-2 and sustained recommendations to wear protective fac... more Despite continued transmission of SARS-CoV-2 and sustained recommendations to wear protective face coverings, many people remained reluctant to comply throughout the early months of the pandemic. In the present study we surveyed an international cohort of participants on three different occasions from July to August, 2020 (N = 695) to examine the relative contribution of several factors in explaining variation in mask wearing behavior across a range of routine and leisure activities. We examine the role of COVID-19 prevalence, perceived risk of infection, COVID-19 related stress, demographics, time orientation, and several mask wearing attitudes and intentions. We find that COVID-19-related stress and the intention to protect oneself were reliably associated with more mask wearing across contexts, while other factors, such as anxiety caused by others’ mask wearing and the intention to wear masks to protect others, were context dependent. We discuss potential avenues for future resea...
In three previous studies, we observe 1) relationship-specific differences in affective empathy, ... more In three previous studies, we observe 1) relationship-specific differences in affective empathy, 2) that relational-interdependence attenuates the positive effect of relational-empathy on willingness to help, 3) and that relational interdependence attenuates the positive effect of state-level empathic concern on willingness to help. Here we tested whether situational-interdependence attenuates the positive effect of empathic concern on helping motivation.
Microbes can influence host physiology and behavior in many ways. Here we review evidence suggest... more Microbes can influence host physiology and behavior in many ways. Here we review evidence suggesting that some microbes can contribute to host stress (and other microbes can contribute to increased resilience to stress). We explain how certain microbes, which we call "stress microbes," can potentially benefit evolutionarily from inducing stress in a host, gaining access to host resources that can help fuel rapid microbial replication by increasing glucose levels in the blood, increasing intestinal permeability, and suppressing the immune system. Other microbes, which we term "resilience microbes," can potentially benefit from making hosts more resilient to stress. We hypothesize that "stress microbes" use a fast life history strategy involving greater host exploitation while "resilience microbes" use a slow life history strategy characterized by more aligned evolutionary interests with the host. In this paper, we review the evidence that microbes affect host stress and explain the evolutionary pressures that could lead microbes to manipulate host stress, discuss the physiological mechanisms that are known to be involved in both stress and microbial activity, and provide some testable predictions that follow from this hypothesis.
Cancers are a leading cause of death in humans and for many other species. Diet has often been as... more Cancers are a leading cause of death in humans and for many other species. Diet has often been associated with cancers, and the microbiome is an essential mediator between diet and cancers. Here we review the work on cancer and the microbiome across species. We systematically reviewed over a thousand published articles and identified links between diet, microbes and cancers in several species of mammals, birds, and flies. Some microbes, specifically Fusobacteria, Bacteroides fragilis, Helicobacter bacteria, and papillomaviruses, have cancer-inducing effects in gerbils, mice, dogs, or cats. Other microbes, such as Lactobacillus species, mostly found in milk products, prevent gastrointestinal, breast, and lung cancers in mice and rats. Future work should examine a larger variety of host species to discover new model organisms for human preclinical trials, better understand the observed variance in cancer prevalence across species, and discover which microbes and diets are associated w...
To better understand risk management and mutual aid among American ranchers, we interviewed and m... more To better understand risk management and mutual aid among American ranchers, we interviewed and mailed a survey to ranchers in Hidalgo County, New Mexico, and Cochise County, Arizona, focusing on two questions: (1) When do ranchers expect repayment for the help they provide others? (2) What determines ranchers' degrees of involvement in networks of mutual aid, which they refer to as "neighboring"? When needs arise due to unpredictable events, such as injuries, most ranchers reported not expecting to be paid back for the help they provide. When help is provided for something that follows a known schedule or that can be scheduled, such as branding, most ranchers did expect something in return for the help they provide. This pattern makes sense in light of computational modeling that shows that transfers to those in need without expectations of repayment pool risk more effectively than transfers that create debt. Ranchers reported helping other ranchers more often when they belonged to more religious and civic organizations, when they owned larger ranches, when they relied less on ranch vs. other income, and when they had more relatives in the area. Operators of midsize ranches reported helping other ranchers more frequently than did those on smaller and larger ranches. None of our independent variables predicted how many times ranchers reported receiving help from other ranchers. Although ranch culture in the American West is often characterized by an ethic of individualism and independence, our study suggests that this ethic stands alongside an ethic of mutual aid during times of need.
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
The application of evolutionary and ecological principles to cancer prevention and treatment, as ... more The application of evolutionary and ecological principles to cancer prevention and treatment, as well as recognizing cancer as a selection force in nature, has gained impetus over the last 50 years. Following the initial theoretical approaches that combined knowledge from interdisciplinary fields, it became clear that using the eco-evolutionary framework is of key importance to understand cancer. We 1.1 | Cancer as a complex eco-evolutionary process Neoplasia has been detected in most multicellular groups, suggesting that its evolutionary roots can be traced back to the evolution This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Trichoplax adhaerens is the simplest multicellular animal with tissue differentiation and somatic... more Trichoplax adhaerens is the simplest multicellular animal with tissue differentiation and somatic cell turnover. Like all other multicellular organisms, it should be vulnerable to cancer, yet there have been no reports of cancer in T. adhaerens, or any other placozoan. We investigated the cancer resistance of T. adhaerens, discovering that they are able to tolerate high levels of radiation damage (218.6 Gy). To investigate how T. adhaerens survive levels of radiation that are lethal to other animals, we examined gene expression after the X-ray exposure, finding overexpression of genes involved in DNA repair and apoptosis including the MDM2 gene. We also discovered that T. adhaerens extrudes clusters of inviable cells after X-ray exposure. T. adhaerens is a valuable model organism for studying the molecular, genetic and tissue-level mechanisms underlying cancer suppression.
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...
According to Turnbull's 1972 ethnography The Mountain People, the Ik of Uganda had a culture of s... more According to Turnbull's 1972 ethnography The Mountain People, the Ik of Uganda had a culture of selfishness that made them uncooperative. His claims contrast with two widely accepted principles in evolutionary biology, that humans cooperate on larger scales than other species and that culture is an important facilitator of such cooperation. We use recently collected data to examine Ik culture and its influence on Ik behaviour. Turnbull's observations of selfishness were not necessarily inaccurate but they occurred during a severe famine. Cooperation re-emerged when people once again had enough resources to share. Accordingly, Ik donations in unframed Dictator Games are on par with average donations in Dictator Games played by people around the world. Furthermore, Ik culture includes traits that encourage sharing with those in need and a belief in supernatural punishment of selfishness. When these traits are used to frame Dictator Games, the average amounts given by Ik players increase. Turnbull's claim that the Ik have a culture of selfishness can be rejected. Cooperative norms are resilient, and the consensus among scholars that humans are remarkably cooperative and that human cooperation is supported by culture can remain intact.
Assessing interdependence between self and specific others has a rich history in psychological sc... more Assessing interdependence between self and specific others has a rich history in psychological science. Here, we report a novel scale to measure Shared Fate. Studies 1 and 2 (N1 = 198, N2 = 216) show that the Shared Fate scale has two factors assessing perceived shared fate and emotional shared fate with a target, has good reliability (Cronbach’s alpha = 0.81 to 0.91; McDonald’s omega = 0.89 to 0.96), and predicts participants’ willingness to help interdependent others. Studies 3 and 4 (N3 = 695, N4 = 629) indicate that the Shared Fate scale has good discriminant, convergent, concurrent, and predictive validity as well as test-retest reliability across a 14-day period. Taken together, our results suggest that Shared Fate scale is a useful instrument for work on cooperation, interdependence, and social behavior. However, there are still many open questions about the cognitive architecture underlying perceptions of shared fate and how shared fate interacts with genetic relatedness and...
Smartphone use changes the landscape of social interactions, including introducing new social dil... more Smartphone use changes the landscape of social interactions, including introducing new social dilemmas to daily life. The challenge of putting down one's smartphone is an example of a classic coordination problem from game theory: the stag hunt game. In a stag hunt game, there are two possible coordination points, one that involves big payoffs for both partners (e.g., working together to hunt large game like stag) and one that involves smaller payoffs for both partners (e.g., individually hunting small game like rabbits) but is safer because it does not require that your partner choose that option as well. This is similar to the challenges of putting down smartphones to have a face-to-face interaction: you and your interaction partner might both prefer the higher payoff option of having a face-to-face interaction, but neither of you wants to put down your phone and risk not having anything to do in the meantime. It is also discussed how new technological innovations are changing the payoffs of face-to-face conversation versus side-by-side smartphone scrolling. Insights that come from applying game theory to this "social media dilemma" are discussed here and potential solutions that come out of a game theoretic analysis are offered.
Kombucha, a fermented tea beverage with an acidic and effervescent taste, is composed of a multis... more Kombucha, a fermented tea beverage with an acidic and effervescent taste, is composed of a multispecies microbial ecosystem with complex interactions that are characterized by both cooperation and conflict. In kombucha, a complex community of bacteria and yeast initiates the fermentation of a starter tea (usually black or green tea with sugar), producing a biofilm that covers the liquid over several weeks. This happens through several fermentative phases that are characterized by cooperation and competition among the microbes within the kombucha solution. Yeast produce invertase as a public good that enables both yeast and bacteria to metabolize sugars. Bacteria produce a surface biofilm which may act as a public good providing protection from invaders, storage for resources, and greater access to oxygen for microbes embedded within it. The ethanol and acid produced during the fermentative process (by yeast and bacteria, respectively) may also help to protect the system from invasio...
Kombucha is a sweetened tea fermented by bacteria and yeast into a carbonated, acidic drink, prod... more Kombucha is a sweetened tea fermented by bacteria and yeast into a carbonated, acidic drink, producing a surface biofilm pellicle (colloquially called a SCOBY) during the process. Typically, liquid and a biofilm pellicle from a previously fermented culture is used as a starter for new cultures; however, there is no standard protocol for growing kombucha in the laboratory. In order to establish a standard protocol with low variability between replicates, we tested whether we could begin a kombucha culture with only well-mixed liquid stock. We found that viable kombucha cultures can be grown from low percentages of initial inoculum stock liquid, that new pellicles can form from liquid alone (with no ‘starter’ pellicle), and that the variation in the pellicle characteristics is lower when only a liquid starter is used (p = 0.0004). We also found that blending the pellicle before including it significantly reduces the variation among replicates, though the final pellicle was abnormal. W...
Philosophical transactions of the Royal Society of London. Series B, Biological sciences, Jan 5, 2017
The capacity to innovate is often considered a defining feature of human societies, but it is not... more The capacity to innovate is often considered a defining feature of human societies, but it is not a capacity that is unique to human societies: innovation occurs in cellular societies as well. Cellular societies such as multicellular bodies and microbial communities, including the human microbiome, are capable of innovation in response to novel opportunities and threats. Multicellularity represents a suite of innovations for cellular cooperation, but multicellularity also opened up novel opportunities for cells to cheat, exploiting the infrastructure and resources of the body. Multicellular bodies evolve less quickly than the cells within them, leaving them vulnerable to cellular innovations that can lead to cancer and infections. In order to counter these threats, multicellular bodies deploy additional innovations including the adaptive immune system and the development of partnerships with preferred microbial partners. What can we learn from examining these innovations in cooperat...
Using an agent-based model to study risk-pooling in herder dyads using rules derived from Maasai ... more Using an agent-based model to study risk-pooling in herder dyads using rules derived from Maasai osotua ("umbilical cord") relationships, Aktipis et al. (2011) found that osotua transfers led to more risk-pooling and better herd survival than both no transfers and transfers that occurred at frequencies tied to those seen in the osotua simulations. Here we expand this approach by comparing osotua-style transfers to another type of livestock transfer among Maasai known as esile ("debt"). In osotua, one asks if in need, and one gives in response to such requests if doing so will not threaten one's own survival. In esile relationships, accounts are kept and debts must be repaid. We refer to these as "need-based" and "account-keeping" systems, respectively. Need-based transfers lead to more risk pooling and higher survival than account keeping. Need-based transfers also lead to greater wealth equality and are game theoretically dominant to acco...
Abundance of immune cells has been shown to have prognostic and predictive significance in many t... more Abundance of immune cells has been shown to have prognostic and predictive significance in many tumor types. Beyond abundance, the spatial organization of immune cells in relation to cancer cells may also have significant functional and clinical implications. However there is a lack of systematic methods to quantify spatial associations between immune and cancer cells. We applied ecological measures of species interactions to digital pathology images for investigating the spatial associations of immune and cancer cells in breast cancer. We used the Morisita-Horn similarity index, an ecological measure of community structure and predator-prey interactions, to quantify the extent to which cancer cells and immune cells colocalize in whole-tumor histology sections. We related this index to disease-specific survival of 486 women with breast cancer and validated our findings in a set of 516 patients from different hospitals. Colocalization of immune cells with cancer cells was significant...
Assessing interdependence between self and specific others has a rich history in psychological sc... more Assessing interdependence between self and specific others has a rich history in psychological science. Here, we report a novel scale to measure Shared Fate. Studies 1 and 2 (N1 = 198, N2 = 216) show that the Shared Fate scale has two factors assessing perceived shared fate and emotional shared fate with a target, has good reliability (Cronbach’s alpha = 0.81 to 0.91; McDonald’s omega = 0.89 to 0.96), and predicts participants’ willingness to help interdependent others. Studies 3 and 4 (N3 = 695, N4 = 629) indicate that the Shared Fate scale has good discriminant, convergent, concurrent, and predictive validity as well as test-retest reliability across a 14-day period. Taken together, our results suggest that Shared Fate scale is a useful instrument for work on cooperation, interdependence, and social behavior. However, there are still many open questions about the cognitive architecture underlying perceptions of shared fate and how shared fate interacts with genetic relatedness and other sources of fitness interdependence.
Despite continued transmission of SARS-CoV-2 and sustained recommendations to wear protective fac... more Despite continued transmission of SARS-CoV-2 and sustained recommendations to wear protective face coverings, many people remained reluctant to comply throughout the early months of the pandemic. In the present study we surveyed an international cohort of participants on three different occasions from July to August, 2020 (N = 695) to examine the relative contribution of several factors in explaining variation in mask wearing behavior across a range of routine and leisure activities. We examine the role of COVID-19 prevalence, perceived risk of infection, COVID-19 related stress, demographics, time orientation, and several mask wearing attitudes and intentions. We find that COVID-19-related stress and the intention to protect oneself were reliably associated with more mask wearing across contexts, while other factors, such as anxiety caused by others’ mask wearing and the intention to wear masks to protect others, were context dependent. We discuss potential avenues for future resea...
In three previous studies, we observe 1) relationship-specific differences in affective empathy, ... more In three previous studies, we observe 1) relationship-specific differences in affective empathy, 2) that relational-interdependence attenuates the positive effect of relational-empathy on willingness to help, 3) and that relational interdependence attenuates the positive effect of state-level empathic concern on willingness to help. Here we tested whether situational-interdependence attenuates the positive effect of empathic concern on helping motivation.
Microbes can influence host physiology and behavior in many ways. Here we review evidence suggest... more Microbes can influence host physiology and behavior in many ways. Here we review evidence suggesting that some microbes can contribute to host stress (and other microbes can contribute to increased resilience to stress). We explain how certain microbes, which we call "stress microbes," can potentially benefit evolutionarily from inducing stress in a host, gaining access to host resources that can help fuel rapid microbial replication by increasing glucose levels in the blood, increasing intestinal permeability, and suppressing the immune system. Other microbes, which we term "resilience microbes," can potentially benefit from making hosts more resilient to stress. We hypothesize that "stress microbes" use a fast life history strategy involving greater host exploitation while "resilience microbes" use a slow life history strategy characterized by more aligned evolutionary interests with the host. In this paper, we review the evidence that microbes affect host stress and explain the evolutionary pressures that could lead microbes to manipulate host stress, discuss the physiological mechanisms that are known to be involved in both stress and microbial activity, and provide some testable predictions that follow from this hypothesis.
Cancers are a leading cause of death in humans and for many other species. Diet has often been as... more Cancers are a leading cause of death in humans and for many other species. Diet has often been associated with cancers, and the microbiome is an essential mediator between diet and cancers. Here we review the work on cancer and the microbiome across species. We systematically reviewed over a thousand published articles and identified links between diet, microbes and cancers in several species of mammals, birds, and flies. Some microbes, specifically Fusobacteria, Bacteroides fragilis, Helicobacter bacteria, and papillomaviruses, have cancer-inducing effects in gerbils, mice, dogs, or cats. Other microbes, such as Lactobacillus species, mostly found in milk products, prevent gastrointestinal, breast, and lung cancers in mice and rats. Future work should examine a larger variety of host species to discover new model organisms for human preclinical trials, better understand the observed variance in cancer prevalence across species, and discover which microbes and diets are associated w...
To better understand risk management and mutual aid among American ranchers, we interviewed and m... more To better understand risk management and mutual aid among American ranchers, we interviewed and mailed a survey to ranchers in Hidalgo County, New Mexico, and Cochise County, Arizona, focusing on two questions: (1) When do ranchers expect repayment for the help they provide others? (2) What determines ranchers' degrees of involvement in networks of mutual aid, which they refer to as "neighboring"? When needs arise due to unpredictable events, such as injuries, most ranchers reported not expecting to be paid back for the help they provide. When help is provided for something that follows a known schedule or that can be scheduled, such as branding, most ranchers did expect something in return for the help they provide. This pattern makes sense in light of computational modeling that shows that transfers to those in need without expectations of repayment pool risk more effectively than transfers that create debt. Ranchers reported helping other ranchers more often when they belonged to more religious and civic organizations, when they owned larger ranches, when they relied less on ranch vs. other income, and when they had more relatives in the area. Operators of midsize ranches reported helping other ranchers more frequently than did those on smaller and larger ranches. None of our independent variables predicted how many times ranchers reported receiving help from other ranchers. Although ranch culture in the American West is often characterized by an ethic of individualism and independence, our study suggests that this ethic stands alongside an ethic of mutual aid during times of need.
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
The application of evolutionary and ecological principles to cancer prevention and treatment, as ... more The application of evolutionary and ecological principles to cancer prevention and treatment, as well as recognizing cancer as a selection force in nature, has gained impetus over the last 50 years. Following the initial theoretical approaches that combined knowledge from interdisciplinary fields, it became clear that using the eco-evolutionary framework is of key importance to understand cancer. We 1.1 | Cancer as a complex eco-evolutionary process Neoplasia has been detected in most multicellular groups, suggesting that its evolutionary roots can be traced back to the evolution This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Trichoplax adhaerens is the simplest multicellular animal with tissue differentiation and somatic... more Trichoplax adhaerens is the simplest multicellular animal with tissue differentiation and somatic cell turnover. Like all other multicellular organisms, it should be vulnerable to cancer, yet there have been no reports of cancer in T. adhaerens, or any other placozoan. We investigated the cancer resistance of T. adhaerens, discovering that they are able to tolerate high levels of radiation damage (218.6 Gy). To investigate how T. adhaerens survive levels of radiation that are lethal to other animals, we examined gene expression after the X-ray exposure, finding overexpression of genes involved in DNA repair and apoptosis including the MDM2 gene. We also discovered that T. adhaerens extrudes clusters of inviable cells after X-ray exposure. T. adhaerens is a valuable model organism for studying the molecular, genetic and tissue-level mechanisms underlying cancer suppression.
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...
According to Turnbull's 1972 ethnography The Mountain People, the Ik of Uganda had a culture of s... more According to Turnbull's 1972 ethnography The Mountain People, the Ik of Uganda had a culture of selfishness that made them uncooperative. His claims contrast with two widely accepted principles in evolutionary biology, that humans cooperate on larger scales than other species and that culture is an important facilitator of such cooperation. We use recently collected data to examine Ik culture and its influence on Ik behaviour. Turnbull's observations of selfishness were not necessarily inaccurate but they occurred during a severe famine. Cooperation re-emerged when people once again had enough resources to share. Accordingly, Ik donations in unframed Dictator Games are on par with average donations in Dictator Games played by people around the world. Furthermore, Ik culture includes traits that encourage sharing with those in need and a belief in supernatural punishment of selfishness. When these traits are used to frame Dictator Games, the average amounts given by Ik players increase. Turnbull's claim that the Ik have a culture of selfishness can be rejected. Cooperative norms are resilient, and the consensus among scholars that humans are remarkably cooperative and that human cooperation is supported by culture can remain intact.
Assessing interdependence between self and specific others has a rich history in psychological sc... more Assessing interdependence between self and specific others has a rich history in psychological science. Here, we report a novel scale to measure Shared Fate. Studies 1 and 2 (N1 = 198, N2 = 216) show that the Shared Fate scale has two factors assessing perceived shared fate and emotional shared fate with a target, has good reliability (Cronbach’s alpha = 0.81 to 0.91; McDonald’s omega = 0.89 to 0.96), and predicts participants’ willingness to help interdependent others. Studies 3 and 4 (N3 = 695, N4 = 629) indicate that the Shared Fate scale has good discriminant, convergent, concurrent, and predictive validity as well as test-retest reliability across a 14-day period. Taken together, our results suggest that Shared Fate scale is a useful instrument for work on cooperation, interdependence, and social behavior. However, there are still many open questions about the cognitive architecture underlying perceptions of shared fate and how shared fate interacts with genetic relatedness and...
Smartphone use changes the landscape of social interactions, including introducing new social dil... more Smartphone use changes the landscape of social interactions, including introducing new social dilemmas to daily life. The challenge of putting down one's smartphone is an example of a classic coordination problem from game theory: the stag hunt game. In a stag hunt game, there are two possible coordination points, one that involves big payoffs for both partners (e.g., working together to hunt large game like stag) and one that involves smaller payoffs for both partners (e.g., individually hunting small game like rabbits) but is safer because it does not require that your partner choose that option as well. This is similar to the challenges of putting down smartphones to have a face-to-face interaction: you and your interaction partner might both prefer the higher payoff option of having a face-to-face interaction, but neither of you wants to put down your phone and risk not having anything to do in the meantime. It is also discussed how new technological innovations are changing the payoffs of face-to-face conversation versus side-by-side smartphone scrolling. Insights that come from applying game theory to this "social media dilemma" are discussed here and potential solutions that come out of a game theoretic analysis are offered.
Kombucha, a fermented tea beverage with an acidic and effervescent taste, is composed of a multis... more Kombucha, a fermented tea beverage with an acidic and effervescent taste, is composed of a multispecies microbial ecosystem with complex interactions that are characterized by both cooperation and conflict. In kombucha, a complex community of bacteria and yeast initiates the fermentation of a starter tea (usually black or green tea with sugar), producing a biofilm that covers the liquid over several weeks. This happens through several fermentative phases that are characterized by cooperation and competition among the microbes within the kombucha solution. Yeast produce invertase as a public good that enables both yeast and bacteria to metabolize sugars. Bacteria produce a surface biofilm which may act as a public good providing protection from invaders, storage for resources, and greater access to oxygen for microbes embedded within it. The ethanol and acid produced during the fermentative process (by yeast and bacteria, respectively) may also help to protect the system from invasio...
Kombucha is a sweetened tea fermented by bacteria and yeast into a carbonated, acidic drink, prod... more Kombucha is a sweetened tea fermented by bacteria and yeast into a carbonated, acidic drink, producing a surface biofilm pellicle (colloquially called a SCOBY) during the process. Typically, liquid and a biofilm pellicle from a previously fermented culture is used as a starter for new cultures; however, there is no standard protocol for growing kombucha in the laboratory. In order to establish a standard protocol with low variability between replicates, we tested whether we could begin a kombucha culture with only well-mixed liquid stock. We found that viable kombucha cultures can be grown from low percentages of initial inoculum stock liquid, that new pellicles can form from liquid alone (with no ‘starter’ pellicle), and that the variation in the pellicle characteristics is lower when only a liquid starter is used (p = 0.0004). We also found that blending the pellicle before including it significantly reduces the variation among replicates, though the final pellicle was abnormal. W...
Philosophical transactions of the Royal Society of London. Series B, Biological sciences, Jan 5, 2017
The capacity to innovate is often considered a defining feature of human societies, but it is not... more The capacity to innovate is often considered a defining feature of human societies, but it is not a capacity that is unique to human societies: innovation occurs in cellular societies as well. Cellular societies such as multicellular bodies and microbial communities, including the human microbiome, are capable of innovation in response to novel opportunities and threats. Multicellularity represents a suite of innovations for cellular cooperation, but multicellularity also opened up novel opportunities for cells to cheat, exploiting the infrastructure and resources of the body. Multicellular bodies evolve less quickly than the cells within them, leaving them vulnerable to cellular innovations that can lead to cancer and infections. In order to counter these threats, multicellular bodies deploy additional innovations including the adaptive immune system and the development of partnerships with preferred microbial partners. What can we learn from examining these innovations in cooperat...
Using an agent-based model to study risk-pooling in herder dyads using rules derived from Maasai ... more Using an agent-based model to study risk-pooling in herder dyads using rules derived from Maasai osotua ("umbilical cord") relationships, Aktipis et al. (2011) found that osotua transfers led to more risk-pooling and better herd survival than both no transfers and transfers that occurred at frequencies tied to those seen in the osotua simulations. Here we expand this approach by comparing osotua-style transfers to another type of livestock transfer among Maasai known as esile ("debt"). In osotua, one asks if in need, and one gives in response to such requests if doing so will not threaten one's own survival. In esile relationships, accounts are kept and debts must be repaid. We refer to these as "need-based" and "account-keeping" systems, respectively. Need-based transfers lead to more risk pooling and higher survival than account keeping. Need-based transfers also lead to greater wealth equality and are game theoretically dominant to acco...
Abundance of immune cells has been shown to have prognostic and predictive significance in many t... more Abundance of immune cells has been shown to have prognostic and predictive significance in many tumor types. Beyond abundance, the spatial organization of immune cells in relation to cancer cells may also have significant functional and clinical implications. However there is a lack of systematic methods to quantify spatial associations between immune and cancer cells. We applied ecological measures of species interactions to digital pathology images for investigating the spatial associations of immune and cancer cells in breast cancer. We used the Morisita-Horn similarity index, an ecological measure of community structure and predator-prey interactions, to quantify the extent to which cancer cells and immune cells colocalize in whole-tumor histology sections. We related this index to disease-specific survival of 486 women with breast cancer and validated our findings in a set of 516 patients from different hospitals. Colocalization of immune cells with cancer cells was significant...
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