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This paper examines the debate over whether Acheulean handaxe shape results from the intentional imposition of a priorly held mental template upon the lithic material substrate or, alternatively, whether a knapper's intentions related to shape ‘emerge’ through the engagement (in action) of human agency and material affordances. We suggest that imposition of form and emergence of form are not mutually exclusive, and use Lave and Wenger's concept of ‘communities of practice’ to knit these opposed views together to explain the consolidation of homogenous handaxe shape at Boxgrove, c. 500,000 years ago. Here we propose that the consistency in handaxe shape found at sites like Boxgrove is a consequence of the emergent actions of individual knappers being simultaneously constrained by the imposition of social norms. Social norms are referred to in action and are negotiated, understood, and adhered to at the wider group level. Therefore, we propose that contextualizing Acheulean handaxe manufacture within its wider social context will show that handaxe shape was both imposed and emergent, not one or the other.

Research in sentence processing has increasingly examined the role of individual differences in language comprehension. In work on native and nonnative sentence processing, examining individual differences can contribute crucial insight into theoretical debates about the extent to which nativelike processing is possible in a nonnative language. Despite this increased interest in individual differences, whether commonly used psycholinguistic tasks can reliably measure individual differences between participants has not been systematically examined. As a preliminary examination of this issue in nonnative processing, we report a self-paced reading experiment on garden-path sentences in native and nonnative comprehension. At the group level we replicated previously observed findings in native and nonnative speakers. However, while we found that our self-paced reading experiment was a reliable way of assessing individual differences in overall reading speed and comprehension accuracy, it did not consistently measure individual differences in the size of garden-path effects in our sample (N = 64 native and 64 nonnative participants, and 24 experimental items). These results suggest that before individual differences in sentence processing can be meaningfully assessed, the question of whether commonly used tasks can consistently measure individual differences requires systematic examination.

A central aim of animal welfare science is to be able to compare the effects of different ways of keeping, managing or treating animals based on welfare indicators. A system to aggregate the different indicators is therefore needed. However, developing such a system gives rise to serious challenges. Here, we focus specifically on the ethical aspects of this problem, taking as our starting point the ambitious efforts to set up an aggregation system within the project Welfare Quality® (WQ). We first consider the distinction between intra- and inter-individual aggregation. These are of a very different nature, with inter-individual aggregation potentially giving rise to much more serious ethical disagreement than intra-individual aggregation. Secondly, we look at the idea of aggregation with a focus on how to compare different levels and sorts of welfare problems. Here, we conclude that animal welfare should not be understood as a simple additive function of negative or positive states. We also conclude that there are significant differences in the perceived validity and importance of different kinds of welfare indicators. Based on this, we evaluate how aggregation is undertaken in WQ. The main conclusion of this discussion is that the WQ system lacks transparency, allows important problems to be covered up, and has severe shortcomings when it comes to the role assigned to experts. These shortcomings may have serious consequences for animal welfare when the WQ scheme at farm or group level is applied. We conclude by suggesting ways to overcome some of these shortcomings.

We suggest that the accounts offered by the target articles could be strengthened by acknowledging the role of group selection and cultural niche construction in shaping the evolutionary trajectory of human music. We argue that group level traits and highly variable cultural niches can explain the diversity of human song, but the target articles' accounts are insufficient to explain such diversity.

Estimation of RMR using prediction equations is the basis for calculating energy requirements. In the present study, RMR was predicted by Harris–Benedict, Schofield, Henry, Mifflin–St Jeor and Owen equations and measured by indirect calorimetry in 125 healthy adult women of varying BMI (17–44 kg/m2). Agreement between methods was assessed by Bland–Altman analyses and each equation was assessed for accuracy by calculating the percentage of individuals predicted within ± 10 % of measured RMR. Slopes and intercepts of bias as a function of average RMR (mean of predicted and measured RMR) were calculated by regression analyses. Predictors of equation bias were investigated using univariate and multivariate linear regression. At group level, bias (the difference between predicted and measured RMR) was not different from zero only for Mifflin–St Jeor (0 (sd153) kcal/d (0 (sd640) kJ/d)) and Henry (8 (sd163) kcal/d (33 (sd682) kJ/d)) equations. Mifflin–St Jeor and Henry equations were most accurate at the individual level and predicted RMR within 10 % of measured RMR in 71 and 66 % of participants, respectively. For all equations, limits of agreement were wide, slopes of bias were negative, and intercepts of bias were positive and significantly (P< 0⋅05) different from zero. Increasing age, height and BMI were associated with underestimation of RMR, but collectively these variables explained only 15 % of the variance in estimation bias. Overall accuracy of equations for prediction of RMR is low at the individual level, particularly in women with low and high RMR. The Mifflin–St Jeor equation was the most accurate for this dataset, but prediction errors were still observed in about one-third of participants.

ObjectiveTo investigate the association between sensory-based food education implemented in early childhood education and care (ECEC) centres and children’s willingness to choose and eat vegetables, berries and fruit, and whether the mother’s education level and children’s food neophobia moderate the linkage.DesignThe cross-sectional study involved six ECEC centres that provide sensory-based food education and three reference centres. A snack buffet containing eleven different vegetables, berries and fruit was used to assess children’s willingness to choose and eat the food items. The children’s parents completed the Food Neophobia Scale questionnaire to assess their children’s food neophobia.SettingECEC centres that provide sensory-based food education and reference ECEC centres in Finland.SubjectsChildren aged 3–5 years in ECEC (n 130) and their parents.ResultsSensory-based food education was associated with children’s willingness to choose and eat vegetables, berries and fruit. This association was stronger among the children of mothers with a low education level. A high average level of neophobia in the child group reduced the children’s willingness to choose vegetables, berries and fruit. No similar tendency was observed in the group that had received sensory-based food education. Children’s individual food neophobia had a negative association with their willingness to choose and eat the vegetables, berries and fruit.ConclusionsChild-oriented sensory-based food education seems to provide a promising method for promoting children’s adoption of vegetables, berries and fruit in their diets. In future sensory food education research, more focus should be placed on the effects of the education at the group level.

In this study, I propose supervisors’ upward leader–leader exchange relationships as an important boundary condition for the relationship between average leader–member exchange (LMX) relationships and a climate for innovation support at the group level. Specifically, I argue that the effect of resource spillover to poor-LMX subordinates within a work group is an important mechanism that leads to the development of a climate that supports innovation. I test the hypothesized moderated-mediation model by using multisource and multiwave data collected from 590 employees and 75 supervisors. The findings indicate that the indirect effect of team LMX relationships on team effectiveness via a climate for innovation support is more positive under high conditions of leader–leader exchange, whereas the effect is less positive under low conditions of leader–leader exchange. Implications and limitations relevant to developing research around LMX and innovation are addressed.

Traditionally, personalised nutrition was delivered at an individual level. However, the concept of delivering tailored dietary advice at a group level through the identification of metabotypes or groups of metabolically similar individuals has emerged. Although this approach to personalised nutrition looks promising, further work is needed to examine this concept across a wider population group. Therefore, the objectives of this study are to: (1) identify metabotypes in a European population and (2) develop targeted dietary advice solutions for these metabotypes. Using data from the Food4Me study (n 1607), k-means cluster analysis revealed the presence of three metabolically distinct clusters based on twenty-seven metabolic markers including cholesterol, individual fatty acids and carotenoids. Cluster 2 was identified as a metabolically healthy metabotype as these individuals had the highest Omega-3 Index (6·56 (sd 1·29) %), carotenoids (2·15 (sd 0·71) µm) and lowest total saturated fat levels. On the basis of its fatty acid profile, cluster 1 was characterised as a metabolically unhealthy cluster. Targeted dietary advice solutions were developed per cluster using a decision tree approach. Testing of the approach was performed by comparison with the personalised dietary advice, delivered by nutritionists to Food4Me study participants (n 180). Excellent agreement was observed between the targeted and individualised approaches with an average match of 82 % at the level of delivery of the same dietary message. Future work should ascertain whether this proposed method could be utilised in a healthcare setting, for the rapid and efficient delivery of tailored dietary advice solutions.

We argue that adopting a sociocultural lens to the origins of intergroup bias is important for understanding the nature of attacking and defending behavior at a group level. We specifically propose that the potential divergence in the development of in-group affiliation and out-group derogation supports De Dreu and Gross's framework but does indicate that more emphasis on early sociocultural input is required.

SUMMARYTo better understand the spread of disease in nature, it is fundamentally important to have broadly applicable model systems with readily available species which can be replicated and controlled in the laboratory. Here we used an experimental model system of fish hosts and monogenean parasites to determine whether host sex, group size and group composition (single-sex or mixed-sex) influenced host-parasite dynamics at an individual and group level. Parasite populations reached higher densities and persisted longer in groups of fish compared with isolated hosts and reached higher densities on isolated females than on isolated males. However, individual fish within groups had similar burdens to isolated males regardless of sex, indicating that females may benefit more than males by being in a group. Relative condition was positively associated with high parasite loads for isolated males, but not for isolated females or grouped fish. No difference in parasite dynamics between mixed-sex groups and single-sex groups was detected. Overall, these findings suggest that while host sex influences dynamics on isolated fish, individual fish in groups have similar parasite burdens, regardless of sex. We believe our experimental results contribute to a mechanistic understanding of host-parasite dynamics, although we are cautious about directly extrapolating these results to other systems.

SUMMARYAccurate detection of infection withMycobacterium bovisin live badgers would enable targeted tuberculosis control. Practical challenges in sampling wild badger populations mean that diagnosis of infection at the group (rather than the individual) level is attractive. We modelled data spanning 7 years containing over 2000 sampling events from a population of wild badgers in southwest England to quantify the ability to correctly identify the infection status of badgers at the group level. We explored the effects of variations in: (1) trapping efficiency; (2) prevalence ofM. bovis; (3) using three diagnostic tests singly and in combination with one another; and (4) the number of badgers required to test positive in order to classify groups as infected. No single test was able to reliably identify infected badger groups if 80% sensitive, at least 94% specific, and able to be performed rapidly in the field.

Over a decade since the completion of the human genome sequence, the promise of personalised nutrition available to all has yet to become a reality. While the definition was originally very gene-focused, in recent years, a model of personalised nutrition has emerged with the incorporation of dietary, phenotypic and genotypic information at various levels. Developing on from the idea of personalised nutrition, the concept of targeted nutrition has evolved which refers to the delivery of tailored dietary advice at a group level rather than at an individual level. Central to this concept is metabotyping or metabolic phenotyping, which is the ability to group similar individuals together based on their metabolic or phenotypic profiles. Applications of the metabotyping concept extend from the nutrition to the medical literature. While there are many examples of the metabotype approach, there is a dearth in the literature with regard to the development of tailored interventions for groups of individuals. This review will first explore the effectiveness of personalised nutrition in motivating behaviour change and secondly, examine potential novel ways for the delivery of personalised advice at a population level through a metabotyping approach. Based on recent findings from our work, we will demonstrate a novel strategy for the delivery of tailored dietary advice at a group level using this concept. In general, there is a strong emerging evidence to support the effectiveness of personalised nutrition; future work should ascertain if targeted nutrition can motivate behaviour change in a similar manner.

The present study examines the immediate impact of empathic attitudes on the receiver, by comparing an empathic conversation (EC) with a neutral one (NC) on experiencing depth (EXP), perceived empathy and vagal tone. We also evaluate if empathy effects depend on personality dispositions relevant to interpersonal functioning. An experimental, counterbalanced, within-subject design was implemented wherein participants (n = 27, age M = 22.6, SD = 4.0, 52% females) talked about a personal, meaningful topic for 20 minutes under both the EC and NC conditions. At the group level, main results indicated that the EC was more effective than the NC in promoting increases in EXP over time (F(1, 25) = 21.04, p < .001, ηp2 = .457) and perceived empathy in women (F(1, 25) = 9.42, p = .005, ηp2 = .264). At the individual level, the NC particularly precluded EXP gains in people expressing a better interpersonal functioning (βs < –.46, ps < .05 for attachment security and empathy and β = .38, p < .05 for aggression), and who also inhibited their vagal tone throughout this very condition (β = .40, p = .024). We conclude that the empathic context has an immediate positive impact on healthy psychological variables, whereas a more impersonal setting would drive people away from this positive effect. Those results are discussed in the light of the role of interpersonal proximity (being empathic to another’s experience and the lack of this attitude) in psychotherapy and healthy functioning.

Most commentators supported the thesis of the target article, though there were also those who were less fully persuaded. I will begin with a response to the most critical commentaries. First, I will justify an evolutionary perspective that includes group organization and nongenetic inheritance. Next, I will discuss the concept of emergence. Following that, I will transition to an exploration of ideas and concerns brought up by some of the more supportive commentators. This will include a discussion of different types of groups; the psychology of group-level traits; the uses and limitations of an institutional perspective; the link between transmission, adaptation, and selection; current and future methodologies; and the variety of fields that may benefit from a group-level traits perspective.

Richerson et al. argue that relatively large culturalFSTvalues provide evidence for group structure and therefore scope for group selection. However, recent research on spatial patterns of cultural variation demonstrates that, as in the genetic case, apparent group structure can be a consequence of geographic clines, not group barriers. Such a pattern limits the scope for cultural group selection.

Gowdy & Krall's target article complements our recent theorizing on group behavior. In our comment, we elucidate complementary aspects of the two theories and highlight the importance of differentiation of selves for human groups to reap the benefits of ultrasociality. We propose that achieving optimal group outcomes depends on the differentiation of individual selves.

On-farm scoring of behavioural indicators of animal welfare is challenging but the increasing availability of low cost technology now makes automated monitoring of animal behaviour feasible. We discuss some of the issues with using automated methods to measure animal behaviour within the context of assessing animal welfare. Automated feeders (eg for dairy calves) can help measure the degree that animals are hungry and have potential to identify sick animals even in group housing. Such equipment is best used for longitudinal studies of individual animals rather than making comparisons between farms. Devices attached to animals (eg accelerometers or GPS devices) can help measure the activity levels of animals with a high degree of accuracy and can easily be transported between farms, making them best suited for welfare assessment at the group level. Automated image analysis has great potential to assess movement within groups of animals, but following individual animals can be difficult. The techniques have been validated against traditional methods (eg direct observation). The accuracy of measures taken automatically varies between methods but can be increased by combining measures. Technological developments have provided us with a variety of tools that can be used to monitor behaviour automatically, and these have great potential to improve our ability to monitor animal welfare indicators on-farm. However, it is important that methods be developed to measure a wider range of behaviour patterns. Animal welfare assessment schemes should not place undue emphasis on behavioural indicators solely on the basis that they can be monitored automatically.

Accurate dietary assessment is an essential foundation of research in nutritional epidemiology. Due to the weaknesses in current methodology, attention is turning to strategies that automate the dietary assessment process to improve accuracy and reduce the costs and burden to participants and researchers. ‘My Meal Mate’ (MMM) is a smartphone application designed to support weight loss. The present study aimed to validate the diet measures recorded on MMM against a reference measure of 24 h dietary recalls. A sample of fifty volunteers recorded their food and drink intake on MMM for 7 d. During this period, they were contacted twice at random to conduct 24 h telephone recalls. Daily totals for energy (kJ) and macronutrients recorded on MMM were compared against the corresponding day of recall usingttests for group means and Pearson's correlations. Bland–Altman analysis was used to assess the agreement between the methods. Energy (kJ) recorded on MMM correlated well with the recalls (day 1:r0·77 (95 % CI 0·62, 0·86), day 2:r0·85 (95 % CI 0·74, 0·91)) and had a small mean difference (day 1 (MMM − recall): − 68 kJ/d (95 % CI − 553, 418 kJ) ( − 16 kcal/d, 95 % CI − 127, 100 kcal); day 2 (MMM − recall): − 441 kJ/d (95 % CI − 854, − 29 kJ) ( − 105 kcal/d, 95 % CI − 204, − 7 kcal)). Bland–Altman analysis showed wide limits of agreement between the methods: − 3378 to 3243 kJ/d ( − 807 to 775 kcal/d) on day 1. At the individual level, the limits of agreement between MMM and the 24 h recall were wide; however, at the group level, MMM appears to have potential as a dietary assessment tool.

David Sloan Wilson has recently revived the idea of a group mind as an application of group selectionist thinking to cognition. Central to my discussion of this idea is the distinction between the claim that groups have a psychology and what I call the social manifestation thesis—a thesis about the psychology of individuals. Contemporary work on this topic has confused these two theses. My discussion also points to research questions and issues that Wilson's work raises, as well as their connection to externalist conceptions of the mind familiar since the work of Putnam and Burge.

ObjectiveTo evaluate the errors incurred by young adults using single portion size colour food photographs to quantify foods and nutrients consumed at six meals on two non-consecutive days.DesignBreakfast menus remained the same for the 2 days; but lunch and dinner menus varied. The amounts of food eaten by individuals were determined by weighing individual serving dishes pre- and post-consumption. The day after eating, all foods consumed were quantified in terms of fractions or multiples of the amounts shown in the food photographs.SubjectsThirty adult volunteers (15 male, 15 female), aged 18–36 years, completed the protocol for day one; 27 (90%) completed day two.ResultsSome foods were more difficult to quantify accurately than others. The largest error range was −38.9% to +284.6% (cheese), whereas the smallest errors were incurred for juice (−21.5% to +34.6%, day one). All subjects who consumed muesli (day one) overestimated (+3.7% to +113.7%). No other foods were consistently over-or underestimated. For foods consumed at breakfast by the same subjects on both days, individual estimation errors were inconsistent in magnitude and/or direction. At the group level, most nutrients were estimated to within ±10% of intake; exceptions were thiamin (+10.5%, day one) and vitamin E (−10.1%, day one; −15.3%, day two). Between 63% and 80% of subjects were correctly classified into tertiles on the basis of estimated intakes.ConclusionsDespite some large food quantification errors, single portion size food photographs were effective when used to estimate nutrient intakes at the group level. It remains to be established whether, under the conditions used in this study, more photographs per food would improve estimates of nutrient intake at the individual level.

Mutual aid societies represent intentional institutionalized cooperation. Groups of individuals pool their resources to provide risk protection and social benefits for themselves in what are usually inhospitable settings. Such organizations are clearly adaptive at the group level. However, their development and maintenance require considerable investment of time and financial resources that could be applied to more individualistic ends. What incentives encourage individuals to assume leadership responsibilities in such organizations? And by what means are free riders prevented from negating the organizations’ efforts by sinking the system?

We argue that Smaldino has not established that group-level traits constitute a unit of selection distinct from selection on individuals, as group-level traits are neither replicators nor interactors. Moreover, we argue that Wimsatt's analysis of emergence and aggregativity supports an understanding of group-level and other emergent traits as explanatorily reducible to the individual level.

The theoretical concepts developed in the target article, in which the author proposes a new paradigm of cultural evolution based not on the individuals' characteristics, but rather on more global collective properties described as “group-traits” (which emerge when a group of individuals exhibit both differentiation and organization), may have a broader scientific impact that transcend the boundaries of social and evolutionary psychology, paving the way for the emergence of macro-neuroeconomics and social evolutionary game theory.

Understanding the cultural evolution of complicated group-level traits requires the mathematical formulation of a dynamical system with birth and death events at multiple levels, that is, at the level of individual humans and at the level of groups of humans. Both levels are characterized by cultural traits that have complicated transmission, innovation, and inheritance mechanisms and that can undergo a form of Lamarckian evolution.

I suggest that we should distinguish between weak and strong group-level traits. It is the latter that are especially problematic for developing models of cultural evolution. Using Campbell's notion of vicarious selection mechanisms, I argue that these mechanisms become intertwined with other group-level traits resulting in selection-transmission thickets that are obstacles to modeling cultural evolution.

Smaldino makes a solid contribution to the literature on the evolution of human social organization by pointing out that group-level-traits (GLTs) often emerge from the interactions of group members in such a way that their effects are not easily partitioned into individual selection. However, we argue that he too readily dismisses institutional analysis as a tool for understanding these traits.

Smaldino's target article draws on and seeks to add to a literature that has partially rejected orthodox, gene-centric evolutionary theory. However, orthodox theory has much to say about group-level traits. The target article does not reference or refute these views, and provides no explicit arguments for this narrow approach. In this commentary we: (i) give two examples of topics that the target article might and probably should have discussed (cultural epidemiology and the psychology of individual differences); and (ii) argue that the orthodox approach has much more to say about the emergence of group-level traits than the target article recognises, or gives credit for.

Smaldino is right to argue that we need a richer theory of group-level traits. He is wrong, however, in limiting group-level traits to units of cultural selection, which require explanations based on group selection. Traits are best understood when explanations focus on both process (i.e., selection) and product (i.e., adaptation). This approach can distinguish group-level traits that arise through within-group processes from those that arise through between-group processes.

Group-level traits (GLTs) clarify the necessity of cultural multilevel selection theory. We propose a revised definition of the GLT concept. We also highlight the need to better understand the interplay between the dimensions of cooperation and coordination in the ontogeny of GLTs.

We agree that emergent group-level properties are important; however, we disagree that current approaches, especially culture-gene coevolutionary (CGC) approaches, have neglected them. We explain how CGC helps demystify the tumult of humans' group-level complexity by “starting at the start,” and why (a) assuming undifferentiated individuals and (b) focusing on cooperation are actually powerful tools to this end.

Smaldino proposes emergent properties of human groups, arising when individuals display both differentiation and organization, constitute a novel unit of cultural selection not addressed by current evolutionary theory. We propose existing theoretical frameworks for maintenance of genetic diversity – social heterosis and social genomes – can similarly explain the appearance and maintenance of human cultural diversity (i.e., group-level traits) and collaborative interdependence.

Following Smaldino's definition, we claim that language is also an emergent group-level trait, and propose two facets (human groups tend to organize in a way to efficiently trigger language and linguistic interactions can render formation of certain social organization) to verify this statement, both of which also provide a general framework to address the future work about group-level traits.

An explicit role for emergent group-level traits, social role diversification, and coordination makes good sense when thinking about human evolution. To most effectively understand these and other facets, we need to move toward an integrative model that assumes niche construction and encompasses positive feedback systems at individual, subgroup and larger group levels, demographic processes, and local ecologies.

Psychological research on social influence illuminates many mechanisms through which role differentiation and collaborative interdependence may affect cultural evolution. We focus here on psychological processes that produce specific patterns of asymmetric influence, which in turn can have predictable consequences for the emergence and transmission of group-level traits.

Smaldino proposes a conceptual extension to the theory of cultural evolution to include emergent group-level traits as a unit of selection. It is important to recognize the role that group-level traits have played in the evolution of human culture. However, the emergent group-level trait of division of labor provides an illustrative example that is implementable within the existing framework of cMLS theory and may not even need a departure from the standard model.

At the group level, reported intakes based on estimates of portion size using IPSAS were very close to the intakes reported in the WI (within 5% for all groups). The limits of agreement are quite narrow, ranging from an underestimate of 41 % of energy intake to an overestimate of 72 % and an underestimate of 47 % of weight of food consumed to an overestimate of 77 %. The vast majority of estimates were within 50% of the value reported using the WI and over a third were within 10 %. IPSAS is accurate, practical, easy to use and provides an excellent alternative to the weighed food diary. This work was funded by the Food Standards Agency.

Introduction Dietary assessment is essential for investigating the relationship between diet and disease. Previously it has been assumed that dietary measures used in adults were appropriate in younger age groups. However research has highlighted that measuring the diets of adolescents in particular, poses unique challenges (Livingstone et al, 2004). It has been suggested the development of new and innovative techniques for obtaining dietary intakes of adolescents could improve the accuracy of reporting in this age group. This study aims to investigate whether DietPhone is a valid dietary assessment tool and whether it is acceptable to use with adolescents. Methods Eleven third year girls were required to keep a five day dietary record using both diet diaries and DietPhone over separate time periods. Comparisons of the mean daily intakes of energy, protein, carbohydrate, total fat and calcium were made between the two methods. Using the Bland & Altman technique, the level of agreement between the two methods was determined. Additionally focus groups were carried out to establish whether this group found DietPhone to be acceptable to use. Results At the group level, analysis revealed good agreement between the two methods for carbohydrate, with a mean difference of 15.9g being observed. However there appears to be a lack of agreement for intakes of energy, protein, total fat and calcium, with mean differences of 169kcal, 9.3g, 8.3g and 72mg respectively. Furthermore wide limits of agreement were observed for all the nutritional parameters measured, suggesting a lack of agreement at the individual level. Nevertheless DietPhone was established as the preferred method of choice during the focus groups. In addition the group identified several modifications that could ultimately improve DietPhone. Conclusion Due to the lack of agreement observed between the two methods, it is not appropriate to recommend replacing diet diaries with DietPhone as a dietary assessment tool at this time. However it appears that participants enjoyed using DietPhone and it was favoured over using diet diaries, suggesting this technology is acceptable to use with this population. Therefore in the future, DietPhone has the potential to improve the accuracy of dietary assessment in adolescents.

AimThe aim of the study was to evaluate the impact of hygiene routines and characteristics of the daycare centre (DCC) on sickness absence in preschool children.BackgroundIn Sweden most children attend daycare outside home during daytime. Daycare outside home results in cognitive and social gains for the children, but it also increases the risk of infectious symptoms. About 17%–30% of the respiratory tract infections in preschool children are due to the daycare stay. Factors of importance for sickness absence in DCC have been studied earlier but no study has had a broader focus on routines and daycare characteristics at the same.MethodsIn 2003–2004 a national sample of 138 DCCs were visited by a study nurses who assisted in filling in a questionnaire on hygiene routines and daycare characteristics. Thereafter the DCC reported sickness absence on group level during two weeks in the autumn and two weeks in the spring.FindingsSickness absence was about 10% both in the autumn and in the spring. Only about 10% of the DCC had written rules about hand washing in children but almost all had unwritten rules. More than 50 children at the DCC and no regular contact with the child health centres were found to be of significant importance for sickness absence using a multiple logistic regression model.

Wilson & Sober's discussion of group selection is marred by the absence of plausible examples of human group-level behavioral adaptation. The trait of authoritarianism is one possible example of such an adaptation. It reduces within-group variance in reproductive success, manifests itself more strongly in response to group-level threat, and is found in a variety of cultures.