Work with infants suggests that the adaptive problems humans faced with respect to plants have left their mark on the human mind

From 2019... How Plants Shape the Mind. Annie E.Wertz. Trends in Cognitive Sciences, Volume 23, Issue 7, July 2019, Pages 528-531. https://doi.org/10.1016/j.tics.2019.04.009

Full PDF: How Plants Shape the Mind (miami.edu)

Abstract: Plants are easy to overlook in modern environments, but were a fundamental part of human life over evolutionary time. Recent work with infants suggests that the adaptive problems humans faced with respect to plants have left their mark on the human mind.

Keywords: cognitive evolutionplantssocial learningavoidanceinfancy

Full text, references, photos, charts, in the PDF above

Plants Are A(n Adaptive) Problem

In many societies, plants are no longer a conspicuous part of human life. Plants are a part of the scenery outside and available for purchase, already packaged and processed, in grocery stores and garden centers. This limited contact with plants may seem perfectly normal, but across the entirety of human history it is quite unusual. Taking as a starting point the emergence of the genus Homo, humans spent 99% of our evolutionary history as hunter–gatherers. In a hunter–gatherer world, there were no such shops where the necessities of life could be easily acquired. Instead, our ancestors had to make a living by effectively utilizing the natural environment. Plants were an essential part of this process.

The archeological record and studies of modern hunter–gatherer and hunter–horticulturalist populations show that humans relied on plants in a variety of ways [1].

Plants are an important component of human diets, particularly the roots, fruits, and nuts of plants. Plant materials are used to construct a diverse array of artifacts and shelters. Plant chemicals are used to facilitate hunting and fishing, as well as in rituals and medicines. However, despite all of these benefits, plants can inflict serious costs. Plants have evolved an impressive set of defenses to protect against damage from herbivores [2]. All plants produce toxic chemical defenses, some of which can be harmful or even fatal to humans when ingested. Some plants also have mechanical defenses, such as thorns or stinging hairs, that can cause serious skin injury and in some cases systemic effects.

The problem is: how do humans figure out which plants are food (or otherwise useful) and which ones are fatal? This turns out to be a very difficult task. There are myriad plant species and herbivores that feed on them. The result of these complex coevolutionary relationships is that, from a human perspective, there are no morphological features common to all edible or toxic plants, even in the scale of the environments humans typically encounter without modern means of travel. Therefore, using general rules such as ‘Avoid plants with white flowers’ or ‘Purple fruits are edible’ simply would not work. In the former case, one would miss out on pears, and in the latter one would end up eating deadly nightshade. Importantly, the presence of difficult-to-detect and potentially fatal toxins makes learning about plants through trial and error sampling very costly. The best outcome for this process involves large amounts of wasted time and repeated exposure to noxious plant defenses. The worst-case scenario is death. These kinds of circumstances select for the evolution of social learning mechanisms [3].

The recurrent adaptive problems our species encountered over evolutionary time have shaped the human mind [4] and it is well known that plant defenses have structured the physiology and behavior of many animal species [2], including humans [5].  Accordingly, along with my colleagues, I have recently proposed a solution for the learning problems plants pose. We argue that the human mind contains a collection of behavioral avoidance strategies and social learning rules geared toward safely acquiring information about plants [6,7]. I will refer to this collection of cognitive systems as Plant Learning and Avoidance of Natural Toxins, or PLANT.

Evidence for PLANT

We have begun testing PLANT with studies of human infants. One line of work examines whether infants possess behavioral strategies that would mitigate plant dangers, similar to plant food rejections in older children [8]. Unlike the animate dangers that infants readily attend to (e.g., snakes, spiders [9]), dangerous plant toxins are difficult to detect but relatively easy to avoid. Plants are quite literally rooted to the spot and consequently can inflict harm only on individuals that come into contact with them. Therefore, we propose that PLANT includes behavioral avoidance strategies that protect infants by minimizing their physical contact with plants. To test this proposal, we present infants with plants and different kinds of control objects and measure their reaching behavior (Figure 1). Our results show that, as predicted, infants are reluctant to touch plants compared with other object types [7,10,11] and touch plants less frequently after making contact with them [10]. Infants are similarly avoidant of benign-looking plants and plants covered in sharp-looking thorns [10], suggesting that they initially treat all plants as potentially dangerous – a sensible strategy given that delicate-ooking plants can be deadly poisonous.

Of course, not all plants can be avoided.  Plant foods and materials must be foraged, which necessarily means coming into contact with plants. In some modern hunter–gatherer societies, plant foraging can begin as early as 2–3 years of age [1]. Therefore, in a second line of work, we are investigating whether infants are vigilant for social information about plants and use it to guide their behavior. These studies allow us to test the proposal that PLANT includes social learning rules.

Thus far, we have found that infants look more often to adults when they first encounter plants, in the time before touching them [11], suggesting that behavioral avoidance strategies operate in concert with social learning processes. This structure would enable infants to observe signals from adults before making contact with potentially dangerous plants. Infants appear to be particularly attuned to social signals that allow them to learn which plants are edible [6,12]. In our studies, we show 6- and 18-month-olds an adult eating pieces of fruit from a plant and a manmade object (Figure 2A).

Despite seeing the same social information demonstrated with both object types, infants identify the plant, over the artifact, as a food source [6]. Once infants have learned that fruits from a particular plant are edible, 18-month-olds generalize this information only to other plants that share the same leaf shape and fruit color [12]. This combination of social learning and restrictive generalization rules would prevent infants from inadvertently ingesting toxic plants.

Seeing the Forest for the Trees

Our empirical findings to date are consistent with the proposed PLANT systems.  Infants appear to deploy a collection of behavioral avoidance strategies and social learning rules for plants. Consequently, PLANT minimizes infants’ exposure to harmful plant defenses and allows them to safely acquire information about the specific plants they encounter from more knowledgeable individuals. In short, this work supports the claim that plants have shaped the human mind.

PLANT is a novel research area that provides fertile ground for future exploration (Figure 2). Of particular interest are cross-cultural studies that can shed light on the development of PLANT in different environments and comparative studies that can clarify the evolution of PLANT. Further, the integral role that plants played in human life and human evolution means that PLANT is likely to be enmeshed in a web of cognitive systems that support broader capacities like food learning, threat mitigation, categorization, and cultural transmission, among others. This interconnectedness makes PLANT an excellent starting point for future inquiry in these areas. At the same time, it is highly unlikely that infants, or adults for that matter, will treat plants as a special category in all circumstances. Research on cognitive systems like PLANT can provide new ways of exploring fundamental aspects of human cognition and understanding the evolution of learning.

Results robustly show that humans across the Globe (25 countries, 6 continents) respond with stronger preferences for dominant leaders when they find themselves in contexts of intergroup conflict

Intergroup Conflict and Preferences for Dominant Leaders: Testing Universal Features of Human Followership Psychology across 25 Countries. Lasse Laustsen, Xiaotian Sheng, Mark van Vugt. Human Behavior & Evolution Society HBES 2021, Jun-Jul 2021. https://www.hbes.com/hbes2021/

Abstract: Research shows that followers exhibit heightened preferences for dominant leaders in situations of intergroup conflict and coalitional competition (e.g. Little et al., 2007; Spisak et al., 2012; Laustsen & Petersen, 2017). Accordingly, humans are theorized to possess an evolved psychology of adaptive followership that flexibly regulates preferences for leader dominance in accordance with levels of intergroup conflict (Laustsen & Petersen, 2015). However, existing research is based exclusively on studies conducted in the US or Western Europe. Consequently, the central claim that the adaptive followership psychology constitutes a human universal remains untested. This project tests if followers across the Globe-spanning 25 countries (across six continents) such as Colombia, Kenya, Pakistan, Hungary and China-hold stronger preferences for dominant leaders during intergroup conflict. Building on existing experimental protocols, subjects we assigned subjects randomly to either an intergroup conflict condition or a no-conflict condition asking them to choose their favored leader from dominant and non-dominant looking alternatives. Results robustly show that humans across the Globe respond with stronger preferences for dominant leaders when they find themselves in contexts of intergroup conflict. Hence, the project provides unique and unprecedented support for the notion of a universal and context sensitive human followership psychology.

Testing the buffering hypothesis: Breastfeeding problems, cessation, and social support in the UK

Testing the buffering hypothesis: Breastfeeding problems, cessation, and social support in the UK. Abigail E. Page, Emily H. Emmott, Sarah Myers. American Journal of Human Biology, May 30 2021. https://doi.org/10.1002/ajhb.23621

Abstract

Objectives: Physical breastfeeding problems can lead women to terminate breastfeeding earlier than planned. In high-income countries such as the UK, breastfeeding problems have been attributed to the cultural and individual “inexperience” of breastfeeding, ultimately leading to lower breastfeeding rates. Yet, cross-cultural evidence suggests breastfeeding problems still occur in contexts where breastfeeding is common, prolonged, and seen publicly. This suggests breastfeeding problems are not unusual and do not necessarily lead to breastfeeding cessation. As humans evolved to raise children cooperatively, what matters for breastfeeding continuation may be the availability of social support during the postnatal period. Here, we test the hypothesis that social support buffers mothers from the negative impact breastfeeding problems have on duration.

Methods: We run Cox models on a sample of 565 UK mothers who completed a retrospective online survey about infant feeding and social support in 2017–2018.

Results: Breastfeeding problems were important predictors of cessation; however, the direction of the effect was dependent on the problem type and type of support from a range of supporters. Helpful support for discomfort issues (blocked ducts, too much milk) was significantly associated with reduced hazards of cessation, as predicted. However, helpful support for reported milk insufficiency was assoicated with an increased hazard of cessation.

Conclusions: Experiencing breastfeeding problems is the norm, but its impact may be mitigated via social support. Working from an interdisciplinary approach, our results highlight that a wide range of supporters who provide different types of support have potential to influence maternal breastfeeding experience.

5 DISCUSSION

In our sample of 565 relatively affluent and well-educated women from the UK, we find that almost everyone reported problems breastfeeding, underlining that breastfeeding problems are the norm rather than the exception. Such problems potentially explain why, as reported elsewhere, 71% of respondents who stopped breastfeeding prior to 8 weeks found infant feeding stressful and 60% emotionally draining (Myers et al., 2021). As women often report feeling unprepared, abnormal and isolated when they encounter common issues (Brown, 2016; Wall, 2001), every attempt should be made to inform women antenatally that breastfeeding is a learnt behavior (Varki et al., 2008) and how best to prepare for, and overcome, future challenges (Brown, 2016; Emmott et al., 2020b).

The women in this study were, overall, well-supported. Unhelpful support was rarely reported, and women frequently indicated a wide range of supporters as providing helpful support. Partners were documented as particularly helpful, as were midwives and health visitors. Beyond these well-established supporters, we also see that the mother's mothers (infant's maternal grandmothers), friends and sisters were also providing helpful support across informational, practical and emotional domains. This indicates that multidimensional social support is an important feature of the postnatal period in the UK, even though women, especially those who are more highly educated, frequently live further from family and friends (Chan & Ermisch, 2015). As we have argued previously (Emmott et al., 2020a, 2021; Emmott & Mace, 2015; Myers et al., 2021), the benefit of an evolutionary anthropological approach is the exploration of investment transfers to mothers from a wide range of supporters due to the emphasis on cooperative childrearing (Emmott & Page, 2019). An evolutionary framework highlights that there are many mechanisms by which support can work, and support which can facilitate breastfeeding need not be limited to health care professionals.

5.1 Hypothesis 1: Breastfeeding problems increase the likelihood of cessation

While breastfeeding problems are frequently reported as reasons to stop breastfeeding (Dewey et al., 2003; DiGirolamo et al., 2005; Verronen, 1982), our results highlight that different types of problems have different associations with breastfeeding cessation. As is demonstrated consistently in other studies (Ahluwalia et al., 2005; Ingram et al., 2002; Kirkland & Fein, 2003; Lamontagne et al., 2008), we find that women who reported not having enough breast milk, or struggling to obtain a good latch, were much more likely to terminate breastfeeding within 3 months. These two problems can be understood as relating to infants' nutritional intake (Ingram et al., 2002; Kirkland & Fein, 2003; Li et al., 2008; Verronen, 1982), as a poor latch can result in less efficient feeding. Some have suggested that insufficient milk is often provided as a reason for stopping breastfeeding because the focus on the infant's wellbeing is a more “acceptable” reason to terminate breastfeeding within a society which often relates breastfeeding to “good” mothering (Ingram et al., 2002; Whelan & Lupton, 1998). While we have no data that can directly speak to whether insufficient milk was overreported, it is worth noting it was the second least reported problem. We also did not ask women why they stopped breastfeeding, thus reducing the motivation to inaccurately report and increasing confidence that insufficient milk was perceived to be an actual problem by participants. In contrast, we found that women who reported having problems with blocked ducts, mastitis, sore nipples or too much breast milk were less likely to terminate breastfeeding. These problems can be conceptualized as relating more to mothers' (not insignificant) pain and discomfort, or issues which require management (i.e., pumping excess milk) (Binns & Scott, 2002). Some women may be more able to endure issues of breastfeeding when it is at their own cost, rather than their infant's, which may relate to common parenting ideals focused on intensive mothering—a primarily white, middle-class emphasis on child centered and self-sacrificial parenting (Reyes-Foster & Carter, 2018). Therefore, as argued by Fahy and Holschier (1988), successful breastfeeding occurs not in the absence of problems, but in the mother's ability to overcome these problems (Binns & Scott, 2002).

5.2 Hypothesis 2: Social support will moderate the negative relationship between breastfeeding problems and cessation

In the un-moderated model, blocked ducts and too much breast milk were associated with reduced hazards of breastfeeding termination. However, by exploring the interactions between social support and breastfeeding problems, it was evident that this effect was driven by support that was considered helpful. Across the blocked ducts models, the lowest hazards of stopping breastfeeding were associated with helpful practical and informational support. Furthermore, women who had issues around blocked ducts or too much breast milk and reported unhelpful informational support (from friends, partners and midwives) were more likely to stop breastfeeding prior to 3 months. It has been reported elsewhere that inconsistent conflicting advice from HCPs results in mothers becoming frustrated, confused and more likely to cease breastfeeding (Garner et al., 2016; Ingram et al., 2002; Lamontagne et al., 2008). While we cannot speak to the specifics of the informational support received by our participants, our results nonetheless indicate that this effect may go beyond HCPs, with unhelpful advice from partners and friends having similar effects.

Contra to predictions, rather than reducing the negative impact of milk insufficiency on duration, support of all types—but particularly emotional support—from sisters, health visitors and midwives was associated with increased likelihoods of cessation. While the direction of causality is unknown, this relationship may be related to a woman's support needs. After experiencing perceived milk insufficiency mothers may wish to switch to formula to ensure infant's weight gain. Thus, informational and practical support may help them wean their infants. Supporters who empathize with a mother's situation or affirm her decision to stop breastfeeding may be experienced as being emotionally supportive. Levels of breastfeeding intent in our sample were high (Myers et al., 2021), potentially increasing the importance of emotional support for women who decide to stop early. This may be particularly important in a UK context where breastfeeding is currently heavily promoted, thus to cease breastfeeding is to go against a central tenant of the prevailing, White middle-class mothering discourse (Crossley, 2009; Faircloth, 2015; Kukla, 2006; Lee, 2007). While our study did not explore women's mental wellbeing, the relationship between breastfeeding expectations, problems and postnatal depression has been well documented (Brown et al., 2016; Shakespeare et al., 2004). This highlights that social support during the postnatal period is not only about prolonging breastfeeding but also about supporting mothers mental wellbeing (Emmott et al., 2020b; Trickey, 2018; UNICEF, 2018).

As indicated above, emotional support goes beyond friends and family. In our interaction models, emotional support moderated the relationship between various problems and duration when it originated from all types of health professionals. Graffy and Taylor (2005), in a qualitative analysis of interviews with 654 women from the UK, report that although women requested informational support, women were more often sensitive to the way HCPs treated them. Alongside practical tips and guidance, they wanted acknowledgement of their experiences and to be reassured that issues during breastfeeding were normal, and thus were encouraged to continue. Clearly, emotional support from HCPs has an important role to play. This is highlighted by the negative impact that poor emotional support from GPs had in our study. Emotionally unsupportive GPs could be increasing maternal stress, making breastfeeding more difficult and further adding to mothers' concerns. Conversely, emotional support, through acknowledgement, reassurance and encouragement (Graffy & Taylor, 2005) may increase a mother's self-efficacy to deal with latching, or other issues.

Support from a wide range of sources interacted with breastfeeding problems to predict duration. However, no significant effects were found for the mother's mother, father and brothers. This result is perhaps less surprising for brothers, given their lower levels of helpful support apparent in Figure 1, but much more surprising for mothers' mothers as they have been identified as key supporters of women in the postpartum period and beyond (Scelza, 2009; Scelza & Hinde, 2019; Sear & Coall, 2011; Sear & Mace, 2008; Snopkowski & Sear, 2015). It may be that our sample lacks the variance required to explore our question in relation to mother's mothers, as the vast majority of women reported helpful support from them. Further analyses in a more diverse sample may help unpack this. Peer supporters also demonstrated a different trend, in which the hazard of termination was the lowest when their support was absent. This probably stems from the fact that unlike GPs, health visitors and midwives, not everyone will encounter a peer supporter (as indicated in Figure 1) and likely only do so when they are facing considerable problems. Therefore, those people receiving help from peer supporters may already be more likely to stop breastfeeding.

5.3 Hypothesis 3: The type of support impacts the moderating effect

Practical support is framed within evolutionary approaches as reducing, or having the potential to reduce, a mother's workload, meaning mothers will have more energy to invest in tasks which maximize lifetime fitness, as construed in the current environment (Emmott & Page, 2019; Kramer & Veile, 2018; Meehan et al., 2013; Page et al., 2021). Consequently, while not true of all types of practical support (e.g., allofeeding—individuals other than the mother feeding the infant [Emmott & Mace, 2015; Myers et al., 2021]), overall, practical support is hypothesized to increase breastfeeding duration. In our sample, in which the majority expressed a wish to breastfeed (Myers et al., 2021), mothers who received helpful practical support from family members may have been able to focus on breastfeeding. This additional energy devoted to breastfeeding may have allowed them to work through problems, providing the time required to access specialist breastfeeding support.

Interestingly, in our sample, moderating practical support was received from the partner's parents (the infant's paternal grandparents), rather than the mothers' parents (the infant's maternal grandparents). Who helps mothers is likely to be partially context specific; nonetheless, evolutionary theories of kinship do predict differential investment by paternal and maternal grandparents (Beise, 2005; Gibson & Mace, 2005; Sear, 2008; Sear & Coall, 2011), suggesting that relatives from different lineages may invest in different types of supportive activities (Sear & Mace, 2008). However, it may also be the case that, as noted above, there is simply more variance in partner's family for us to pick up on these trends. It is also important to note that, by focusing on helpfulness, in this analysis we have explored all types of practical support collectively, combining allofeeding with other forms of practical support. Since allofeeding has been demonstrated to have a negative relationship with breastfeeding duration (Emmott & Mace, 2015), this may be confounding results in relation to supporters most likely to perform allofeeding—which in this sample are the partner and mother's mother (Myers et al., 2021).

Our data indicate that emotional and practical support were important moderators; however, contra predictions, so was informational support. While this hypothesis was not formally designed to separate the independent effects of emotional, practical and informational support, we did see that informational support was the most frequent moderator, and the receipt of helpful informational support was often associated with a lower likelihood of breastfeeding cessation. This underlines the fact that breastfeeding is a learnt behavior (Volk, 2009) and suggests while women benefit from practical and emotional support helping them to persist in spite of problems, informational support may curtail the duration of the problem itself. It may also be that the usefulness of informational support is dependent on its delivery alongside emotional support (Fallon et al., 2017; Fallon et al., 2019; Trickey, 2018). Future work should tease out these effects in greater depth.

Informational support was not limited to HCP but also received from partners, sisters and friends. Similar results have been found elsewhere; for example, Swedish mothers whose own mothers had discussed breastfeeding with them were more likely to breastfeed for longer, reporting greater increased confidence (Ekström et al., 2003). This demonstrates the importance of information and advice from a range of supporters. Consequently, researchers and public health specialists need to consider where else information is coming from and how to direct (helpful) information-based interventions beyond the mother (Daniele et al., 2018; Negin et al., 2016; Wolfberg et al., 2004).

Our focus on the physiological experience of breastfeeding problems and the individual experience of social support is not to suggest that wider socioeconomic and political factors are not key predictors of breastfeeding, nor is it easy to untangle the impact of behavior, norms and structural factors (Palmquist & Doehler, 2014). There are large inequalities in infant feeding experience along structural lines in the UK and similar HIC (Victora et al., 2016), contributing to socioeconomic gradients in inflammation and infant weight (McDade & Koning, 2021). These inequalities exist due to cultural and religious norms around breastfeeding, particularly in public (Chang et al., 2021), access to social support (Grubesic & Durbin, 2020; Tomori, 2009), opportunity costs of breastfeeding (Hough et al., 2018; Tully & Ball, 2018), as well having convenient and quick-to-access places to breastfeed (Brown et al., 2020; Hauck et al., 2020). Furthermore, the experience of breastfeeding problems is unlikely to be evenly distributed as one study found that young, unmarried and non-college educated US women were more likely to experience breastfeeding problems resulting in disrupted lactation (Stuebe et al., 2014). Therefore, our results may be underplaying the importance of breastfeeding problems given our sample of educated, affluent white women, who likely have privileged access to formal and informal social support. Here, we have demonstrated the importance of variation in social support in moderating the relationship between breastfeeding problems and duration, but further research with a more diverse sample is required to explore what causes variations in this support.

5.4 Limitations

We have already noted that our sample is a key limitation in this research. While 565 women is not an insignificant sample size, there was a lack of diversity in breastfeeding durations and support received. This is a product of the homogenous nature of our sample, which is largely educated, affluent and white—a clear limitation of this study. As a result, statistical power was likely an issue in our models increasing the likelihood of Type II errors. For this reason, while we often see nonoverlapping confidence intervals between helpful and unhelpful support, the intervals for unhelpful support are often wide and spanning one making interpretation difficult. Our sample was recruited online using convenience-sampling, which likely biased it to more affluent women (Topolovec-Vranic & Natarajan, 2016). This issue is not uncommon within survey-based breastfeeding studies and should be addressed in future research. Middle-class, more affluent women have the time, energy and desire to engage with scientific studies; more needs to be done to make this process low cost and desirable to a wider demographic. An additional concern with online-based data collection are programs which automatically fill in surveys (e.g., bots) (Dupuis et al., 2019) and low effort respondents, both which are likely to occur when financial incentive is offered for survey completion (Buchanan & Scofield, 2018). No financial incentive was offered for the present survey, reducing our concern regarding bots—which is further diminished by the absence of suspiciously rapid completion times. Furthermore, the majority (78.6%) of respondents invested significant effort into responding to a number of optional open-text questions (not used in this analysis, but utilized in Emmott et al. (2020a))—these would be expected to be skipped by low-effort respondents and either skipped, answered incoherently, or repetitively by bots, which data exploration points against.

The second limitation is the potential for reporting bias due to the retrospective design of this study. We asked women with children aged up to 24 months of age about the problems they experienced and support they received since giving birth. Women may forget key early events in the light of later ones, and the perceived severity of a problem is likely impacted by the severity of later ones (Williamson et al., 2012). Further, given the retrospective nature of this study we have captured breastfeeding problems in a simplistic fashion. Our binary measure of yes/no hides variation in severity, duration, and number of occurrences as well as varying causes or exacerbating factors (such as maternal or infant factors). Prospective study designs are better-suited to explore the causal relationship between support, problems and breastfeeding—all factors which fluctuate on a daily basis—and we encourage their future use.

A veil of ignorance can promote fairness in a mammal society

H. H. Marshall, R. A. Johnstone, F. J. Thompson, H. J. Nichols, D. Wells, J. I. Hoffman, G. Kalema-Zikusoka, J. L. Sanderson, E. I. K. Vitikainen, J. D. Blount, M. A. Cant. A veil of ignorance can promote fairness in a mammal society. Nature Communications, 2021; 12 (1) DOI: 10.1038/s41467-021-23910-6

Abstract: Rawls argued that fairness in human societies can be achieved if decisions about the distribution of societal rewards are made from behind a veil of ignorance, which obscures the personal gains that result. Whether ignorance promotes fairness in animal societies, that is, the distribution of resources to reduce inequality, is unknown. Here we show experimentally that cooperatively breeding banded mongooses, acting from behind a veil of ignorance over kinship, allocate postnatal care in a way that reduces inequality among offspring, in the manner predicted by a Rawlsian model of cooperation. In this society synchronized reproduction leaves adults in a group ignorant of the individual parentage of their communal young. We provisioned half of the mothers in each mongoose group during pregnancy, leaving the other half as matched controls, thus increasing inequality among mothers and increasing the amount of variation in offspring birth weight in communal litters. After birth, fed mothers provided extra care to the offspring of unfed mothers, not their own young, which levelled up initial size inequalities among the offspring and equalized their survival to adulthood. Our findings suggest that a classic idea of moral philosophy also applies to the evolution of cooperation in biological systems.

Popular version: Mongooses solve inequality problem -- ScienceDaily

Introduction

The idea that impartiality or ignorance on the part of decision-makers promotes cooperation and fairness in human societies has a long pedigree in philosophy and economics1,2,3. Individuals that are blind to their own gains are predicted to allocate resources for the good of the group rather than themselves1, typically reducing inequality2. In biology, an analogous argument has been proposed as a mechanism for the evolution of cooperation among self-interested agents4,5. Meiosis, for example, ensures that each allele has an equal chance of ending up in any given offspring, creating a “Mendelian veil of ignorance”4, which aligns the fitness interests of each gene with that of the organism4,6,7,8. In insect societies, uncertainty over relatedness promotes cooperative behaviour: workers cooperate to raise the offspring of other workers when relatedness to offspring is uncertain, but kill such offspring when they can discriminate worker-laid vs. queen-laid eggs5. Our aim was to understand if a veil of ignorance over kinship can also promote fairness in an animal society, in the sense of a redistribution of resources to reduce initial inequalities, analogous to Rawls’2 redistributive concept of fairness in human societies.

We studied fairness in the allocation of postnatal care in wild groups of cooperatively breeding banded mongooses Mungos mungo9. The veil of ignorance arises in this system because multiple females (mean ± s.d. = 5.0 ± 2.6, n = 84 litters) synchronize birth to the same morning in a shared underground den. There is good evidence that this extreme birth synchrony removes cues to the parentage of offspring. First, mothers are observed to suckle pups in synchronously produced litters without any apparent discrimination, and pups move from female to female to suckle in a single suckling session10. Second, after pups emerge from the den parents and other helpers do not preferentially care for more closely related offspring in communal litters11. Third, on rare occasions when cues to parentage are available (e.g., in the minority of breeding attempts that are asynchronous12, or when older females are reproductively suppressed using contraceptives13), females kill the pups of other females rather than care for them, suggesting that such cues are absent in natural, synchronous litters.

The communal litter (hereafter “litter”) is suckled underground and guarded at the den by babysitters for the first month, after which the pups emerge from the den and form one-to-one caring relationships with particular adults, called escorts11,14,15. Escorts, who can be any adult male or female in the group, feed and protect the pup in their care until it reaches nutritional independence at around 90 days old (see “Methods”). Both escorts and pups contribute to maintaining the association14,16,17,18. Escorts individually recognize and preferentially respond to the calls of “their” particular pup16,18, and actively seek out their pup if it becomes separated or lost14. Escorts almost exclusively provision the pup with which they are associated14,19, and young pups receive almost all their food from their escort19. Pups, for their part, aggressively defend access to their escort14,15,17 and beg continuously for food16. Pups who receive more escorting are heavier at independence20 and heavier pups are more likely to survive21.

Below we develop a simple game theoretical model to investigate how the veil of ignorance over parentage in banded mongoose communal litters might influence fairness in the distribution of postnatal care among the offspring. We test our model by creating inequalities among helpers and among offspring through the targeted provisioning of pregnant females, and then measuring whether mothers and helpers act to reduce or amplify these inequalities.

Both Democrats & Republicans provide examples of the other party behaving badly, & react most negatively toward incivility when someone from their out-group party is engaging in it; both think that the other side is to blame

Conservatives and Incivility. Ashley Muddiman. Chapter in Conservative Political Communication, 1st Edition. Routledge 2021. https://www.taylorfrancis.com/chapters/edit/10.4324/9781351187237-8/conservatives-incivility-ashley-muddiman

Abstract: This chapter investigates the question, to what extent do Republicans and Democrats agree on what counts as unacceptable, uncivil behavior in U.S. politics? A series of studies indicates that there are not as many differences between political partisans as may be expected. Republicans and Democrats largely provide similar examples of incivility. When exposed to descriptions of incivility, Republicans and Democrats react in similar ways. Finally, when selecting news, both Republicans and Democrats are slightly attracted to civil rather than uncivil news. Instead of a difference between partisans, the studies detailed in this chapter consistently find that partisans of any kind react to incivility in a partisan way. Both Democrats and Republicans provide examples of the other party behaving badly, and both react most negatively toward incivility when someone from their out-group party is engaging in it. Instead of exposing widespread differences between Republicans and Democrats, the studies tell a different story: partisans react similarly to incivility, but they think that the other side is to blame.

From 2019... Vocabulary skills declined among American adults within levels of educational attainment, 1974–2016

From 2019... Declines in vocabulary among American adults within levels of educational attainment, 1974–2016. Jean M. Twenge, W. Keith Campbell, Ryne A. Sherman. Intelligence, Volume 76, September–October 2019, 101377. https://doi.org/10.1016/j.intell.2019.101377

Highlights

• When controlled for educational attainment, adults' vocabulary skills have declined.

• The vocabulary of U.S. college graduates was lower in the 2010s vs. the late 1970s.

• Vocabulary declined across all levels of educational attainment.

• The decline in vocabulary is primarily a time period effect.

Abstract: We examined trends over time in vocabulary, a key component of verbal intelligence, in the nationally representative General Social Survey of U.S. adults (n = 29,912). Participants answered multiple-choice questions about the definitions of 10 specific words. When controlled for educational attainment, the vocabulary of the average U.S. adult declined between the mid-1970s and the 2010s. Vocabulary declined across all levels of educational attainment (less than high school, high school or 2-year college graduate, bachelor's or graduate degree), with the largest declines among those with a bachelor's or graduate degree. Hierarchical linear modeling analyses separating the effects of age, time period, and cohort suggest that the decline is primarily a time period effect. Increasing educational attainment has apparently not improved verbal ability among Americans. Instead, as educational attainment has increased, those at each educational level are less verbally skilled even though the vocabulary skills of the whole population are unchanged.