Increasing Group Size Research Articles

What influences aggression and foraging activity in social birds? Measuring individual, group and environmental characteristics

AbstractFor specialised feeders, accessing food resources may impact on the performance of appetitive foraging and social behaviours at individual and population levels. Flamingos are excellent examples of social species with complex, species‐specific feeding strategies. As attainment of coloured plumage depends upon intake of dietary carotenoids, and as study of free‐ranging flamingos shows that foraging is disrupted by aggression from other birds, we investigated the effect of four feeding styles on foraging and aggression in captive lesser flamingos. We evaluated individual and group differences in foraging and aggression when birds consumed bespoke “flamingo pellet” from a bowl, an indoor feeding pool and an outdoor feeding section of their pool. Natural foraging (when birds were feeding irrespective of the presence of pellet) was recorded for comparison with artificial feeding styles. One‐minute long video footage of the birds' activities in these different locations, recorded between 2013 and 2016, was used to evaluate behaviour. Total number of seconds engaged in feeding and in aggression was recorded by continuous sampling. The colour of individual birds was scored from 1 (mainly white) to 4 (mainly pink). For natural filter feeding in the outdoor pool, maximum foraging was twice as much as bowl feeding, whilst aggression was less than half as much as other feeding methods. Overall, a more restricted feeding style significantly predicted aggression, along with increasing group size. Plumage colour significantly influenced aggression (brightest flamingos were more aggressive) and showed a non‐significant trend with foraging (brighter birds fed less than paler birds). No sex effect on feeding or aggression was found. This study enhances our understanding of husbandry and species' biology impacts on captive behaviour and provides data‐based evidence to improve food presentation. For flamingos, implementation of spacious outdoor feeding areas can encourage natural foraging patterns by reducing excess aggression and enhances welfare by improving flock social stability.

Ecological drivers of group size variation in sika deer: habitat structure, population density, or both?

Habitat structure and population density have long been considered key factors in determining intraspecific variation in the group size of social ungulates. However, the effect of interaction between habitat structure and population density on group size is poorly understood, and whether the underlying causes of these relationships are biological adaptation, emergent properties, or both is still debated. Therefore, over 10 years, we examined group size of the sika deer (Cervus nippon) at different population densities and habitat types (open habitats vs closed forests). We found that deer group size was larger in open habitats than closed forests and increased with population density, and population density and habitat type had a synergistic effect on group size. There was greater density effect in open habitats, while the density effect was very weak in closed forests. Our findings in open habitat support emergent properties, because both population density and visibility enhanced the frequency of group fusion. Alternatively, our findings in closed forests support biological adaptation; the scarce food supply in closed forests may increase the cost of conspecific feeding competition, which consequently limits group size even under high densities. We suggest that both emergent properties and biological adaptation determine group size variability of sika deer, and emergent properties may be the mechanism that contributes to group size increase, whereas biological adaptation may be the mechanism that contributes to group size restriction.

Three-dimensional analysis of pile groups subject to torsion

A series of three-dimensional finite-element models was developed to investigate the non-linear behaviour of pile groups connected to rigid caps and subjected to torsion. Pile groups of sizes 1 × 2, 2 × 2 and 3 × 3 installed in sand were analysed to investigate group resistance as well as the variation of pile flexural and torsion deformation. Furthermore, the relative contributions of the pile cap, pile torsion resistance and pile lateral resistance to group torsion resistance were quantitatively evaluated. The influence of group size, pile spacing, pile length, cap condition and soil stiffness was thoroughly explored. Piles were assumed to behave in a linear elastic fashion, while soil was modelled by way of the non-linear hardening-soil model. The numerical results showed that the contribution of the torsion strength of individual piles to the group overall strength decreases with the increase in group size and pile spacing but increases with the increase in pile length and soil stiffness. Among these parameters, the torsion resisted by individual piles ranged from 20 to 45% of the external applied torque. Moreover, it is found that the pile cap contributes about 7% of group resistance for surface pile caps, while this contribution increases up to 53% for embedded pile caps.

Extended parenting and the evolution of cognition.

Traditional attempts to understand the evolution of human cognition compare humans with other primates. This research showed that relative brain size covaries with cognitive skills, while adaptations that buffer the developmental and energetic costs of large brains (e.g. allomaternal care), and ecological or social benefits of cognitive abilities, are critical for their evolution. To understand the drivers of cognitive adaptations, it is profitable to consider distant lineages with convergently evolved cognitions. Here, we examine the facilitators of cognitive evolution in corvid birds, where some species display cultural learning, with an emphasis on family life. We propose that extended parenting (protracted parent-offspring association) is pivotal in the evolution of cognition: it combines critical life-history, social and ecological conditions allowing for the development and maintenance of cognitive skillsets that confer fitness benefits to individuals. This novel hypothesis complements the extended childhood idea by considering the parents' role in juvenile development. Using phylogenetic comparative analyses, we show that corvids have larger body sizes, longer development times, extended parenting and larger relative brain sizes than other passerines. Case studies from two corvid species with different ecologies and social systems highlight the critical role of life-history features on juveniles' cognitive development: extended parenting provides a safe haven, access to tolerant role models, reliable learning opportunities and food, resulting in higher survival. The benefits of extended juvenile learning periods, over evolutionary time, lead to selection for expanded cognitive skillsets. Similarly, in our ancestors, cooperative breeding and increased group sizes facilitated learning and teaching. Our analyses highlight the critical role of life-history, ecological and social factors that underlie both extended parenting and expanded cognitive skillsets. This article is part of the theme issue 'Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals'.

The group size effect and synchronization of vigilance in the Tibetan wild ass

Vigilance behavior is considered as an effective strategy for prey species to detect predators. An individual benefits from living in a group by reducing the time spent being vigilant without affecting the probability of detecting a predator. However, the mechanism producing a decrease in vigilance with increasing group size is unclear. Many models of vigilance assume that group members scan independently of one another. Yet in recent studies, the other 2 patterns of vigilance, coordination and synchronization, were reported in some species. In 2 summers (2018 and 2019), we studied the group-size effect on vigilance and foraging of Tibetan wild ass in Chang Tang Nature Reserve of Tibet. We also tested whether individuals scan the environment independently, tend to coordinate their scans, or tend to synchronize their vigilance. The results showed that individuals decreased the time spent on vigilance with increasing group size, while increased the time spent foraging. Group members scanned the environment at the same time more frequently and there was a positive correlation between group members’ behaviors, indicating that Tibetan wild asses tend to synchronize their vigilance.

Nudging Mobile Customers with Real-Time Social Dynamics

The proliferation of mobile and sensor technologies has contributed to the rise of location-based mobile targeting. Beyond the location, time and spatial context of individuals, the social context wherein they are embedded can reveal rich information about individual behavior. In this study, we automatically detected the real-time social contexts of customers based on their detailed GPS trajectories using machine-learning methods. To evaluate the effectiveness of mobile targeting under different social contexts, we designed a randomized field experiment in a large shopping mall in 2015. Our analyses indicated significant heterogeneity in consumer behavior under different social contexts. We found a customer in a group with others is on average 1.5 times more responsive to mobile promotions than is a solo shopper, and this impact increases with increased group size (from dyad to triad). We also found significant heterogeneous interactions between mobile promotion design and social contexts. Overall, our study demonstrates the potential of inferring individuals’ social contexts from their movement trajectories and the value of leveraging such real-time social dynamics for improved mobile-targeting effectiveness.

The role of peer reward and punishment for public goods problems in a localized society

Cooperation in social dilemmas can be sustained if individuals are effectively rewarded or punished from peers within the group. However, as group size increases, we inevitably face localization, in which a global group is divided into several localized groups. In such societies, members can reward and punish only neighbors within the same localized group, while cooperation for social dilemmas should be solved through global group involvement. In this situation, the global group and the local group are not always equal in terms of welfare, and situations can arise in which cooperation is beneficial for the global group but not for the local group. We predict that in such a locally inefficient situation, peer reward and punishment cannot function to sustain global cooperation. We conducted an experiment in which 16 group members played a public goods game incorporating peer reward and punishment. We manipulated the range of peer reward and punishment (only local members/all global members) and payoff structure (locally efficient/locally inefficient). We found that high cooperation was not achieved and that peer reward and punishment did not function when, and only when, the group was divided into localized groups and the payoff structure was locally inefficient.

Factors Affecting Group Size and Vigilance Behaviour of Maasai Giraffe (Giraffa camelopardalis tippelskirchi) on the Serengeti-Ngorongoro Ecosystem, Tanzania

This study investigated the factors affecting different group sizes of Maasai giraffe (Giraffa camelopardalis tippelskirchi) in the Serengeti-Ngorongoro ecosystem. The study was motivated to test the following hypotheses: 1) in a given group, the sex ratio of males to females with calves is related to group size; 2) group size affects vigilance behaviour; 3) illegal hunting influences group size and vigilance behaviour; and 4) group size differs in different habitats, being larger in woodlands during the wet season and in riverine habitats during the dry season. A negative relationship between the ratio of the proportion of adult males to females with calves and group size was observed, whereas the proportion of females and calves increased with group size. The proportion of vigilant individuals decreased with an increase in group size. Habitat, risk of illegal hunting and proportion of calves in the group was found to be significant contributors to an increase in vigilance behaviour. However, the results do not support the hypotheses that seasonality and habitat preference affect group sizes of the Maasai giraffes. Emphasis should be put on anti-poaching efforts on males and nursery groups, especially in areas with a high risk of illegal activities.

Trends in the occurrence of large Whooping Crane groups during migration in the great plains, USA

Recent detections of large gatherings of Whooping Cranes suggest that flock sizes may be increasing at some stopover locations during both the spring and fall migrations. We used the public sightings database managed by the US Fish and Wildlife Service from 1942 to 2018 to analyze data for long-term trends in group size. We then examined the spatial distribution of large groups to explore potential explanations for these occurrences. The proportion of Whooping Crane groups comprised of 2, 3, and 4–6 individuals showed no trend over time. However, observations of individuals showed a declining trend and groups of 7–9 and ≥10 showed an increasing trend. The frequency of groups observed exceeding 5 and 10 individuals were better predicted by survey year than by Whooping Crane population size suggesting that an increasing population is not the sole driver of large group occurrences. Our results indicate that large groups occur disproportionately within the 50% migration corridor, at staging areas within the first or last 20–30% of the migration path, and near conservation-managed wetlands, particularly within the southern Great Plains. Our results suggest that in addition to population growth, conspecific attraction, location within the migration corridor, and habitat loss may be contributing to large group occurrences. Further research is needed to determine the degree to which these factors influence large Whooping Crane group formation. The gathering of large numbers of Whooping Cranes in a single location presents potential tradeoffs for the species. While increasing group sizes may improve threat detection and avoidance, it comes at a cost of increased disease and mass mortality risk.

Describing the Pearson R distribution of aggregate data.

Ecological studies and epidemiology need to use group averaged data to make inferences about individual patterns. However, using correlations based on averages to estimate correlations of individual scores is subject to an "ecological fallacy". The purpose of this article is to create distributions of Pearson R correlation values computed from grouped averaged or aggregate data using Monte Carlo simulations and random sampling. We show that, as the group size increases, the distributions can be approximated by a generalized hypergeometric distribution. The expectation of the constructed distribution slightly underestimates the individual Pearson R value, but the difference becomes smaller as the number of groups increases. The approximate normal distribution resulting from Fisher's transformation can be used to build confidence intervals to approximate the Pearson R value based on individual scores from the Pearson R value based on the aggregated scores.

Impact of environmental enrichment and social group size in the aggressiveness and foraging activity of Serrapinnus notomelas

Fish are widely used in scientific research, and many species are bred for ornamental purposes and human consumption. Despite the large number of fish kept in captivity, research on the welfare of these animals has only recently intensified. One commonly used method for improving fish welfare is environmental enrichment, and the issue of animal density is central to this debate. Both enrichment and variation in fish density may have different impacts on the welfare of fish, which will depend on the biology of each species. In this study, we verified if environmental enrichment reduced aggressiveness and increased foraging activity in Serrapinnus notomelas in captivity. S. notomelas is a Neotropical characin commonly used in the aquarium trade. It has also been reared in captivity for scientific research purposes. However, studies on the welfare of S. notomelas in captivity are still lacking. We measured the aggressiveness and foraging activity of fishes in aquariums with different levels of enrichment (enriched and highly enriched), in comparison to an enrichment-free aquarium. The same behavioral aspects were quantified in groups of six and 12 individuals since it is known that group size influences these characteristics in shoal fishes. We found no influence of environmental enrichment on the species’ aggressiveness. However, fish housed in highly enriched aquariums increased their foraging activity to levels similar to fish housed in enrichment-free aquariums. We also found no influence of group size on the aggressiveness of individuals. However, increased group size had a positive effect on foraging activity, therefore we suggest housing S. notomelas with a minimum of 12 individuals. Results reinforce the need for species-specific investigation regarding both enrichment and shoal size to improve the welfare of captive fishes. We also encourage future studies on the effects of different enrichment levels, because we found that the level of enrichment affected the welfare of S. notomelas.

Cooperation in Groups of Different Sizes: The Effects of Punishment and Reputation-Based Partner Choice.

Reputation and punishment are two distinct mechanisms that facilitate cooperation among strangers. However, empirical research on their effectiveness is mainly limited to relatively small groups and does not address how they enhance cooperation in relatively larger groups. We address this gap in the literature by testing hypotheses from competing perspectives about the extent to which reputation-based partner choice and punishment enhance cooperation in both small and large groups. Prior work recognizes that an increase in group size is accompanied by a change in the incentive structure, which determines whether the temptation (extra benefit for each person from non-cooperation over cooperation, regardless of others’ choices) or gain (extra benefit for each person from full cooperation over full non-cooperation) remains constant or varies with group size. Thus, we first test how group size affects cooperation when temptation or gain increases with group size (Study 1), and then move on to testing predictions on the effectiveness of reputation and punishment across different group sizes (Study 2). In Study 1 (N = 820), we randomly assigned participants to play an online one-shot public goods game in groups of 4, 20, or 40, while keeping the marginal group return or marginal per capita return fixed across groups, in which case the temptation or gain increased with group size. In Study 2 (N = 1,132), we further compared a public goods situation involving a punishment or reputation mechanism with an anonymous situation across group sizes, while the marginal group return was fixed across groups. Overall, we found that when temptation increased with group size, 20-person groups cooperated significantly less than 4-person groups in one-shot interactions, and that this effect was explained by lower expectation of others’ cooperation, less perceived collective efficacy, and greater perceived conflict. However, 40-person and 4-person groups did not vary in one-shot cooperation. Importantly, reputation-based partner choice and punishment invariably promoted one-shot cooperation in groups of different sizes. These findings suggest no simple effect of group size on cooperation and underscore the utility of reputation and punishment in fostering cooperation (at least in one-shot interactions) regardless of the size of groups.

The Contributions of Diversity, Accuracy, and Group Size on Collective Accuracy

In this paper, we characterize a group's collective accuracy on a classification problem as a function of its diversity, size, and its member's individual accuracies. We first derive necessary and sufficient conditions on the individuals' classification models for the existence of an aggregation function that produces perfect accuracy. We then characterize the set of possible group accuracies under majority rule. For majority rule, we show that increasing individual accuracy produces a setwise increase in collective accuracy. In contrast, increases in diversity and size have conditional effects. For groups with low diversity, increasing either diversity or size increases the set of possible group accuracies but does not change the set's midpoint. For highly diverse groups, increasing diversity weakly increases setwise accuracy, whereas increases in group size need not. In an extension, we consider a collection of classification models drawn from a population and derive a general condition for increasing group size to raise or lower expected accuracy.

Threshold Models of Collective Behavior II: The Predictability Paradox and Spontaneous Instigation

Collective behavior can be notoriously hard to predict. We revisited a possible explanation suggested by Granovetter’s classic threshold model: collective behavior can unexpectedly fail, despite a group’s strong interest in the outcome, because of the sensitivity of cascades to small random perturbations in group composition and the distribution of thresholds. Paradoxically, we found that a small amount of randomness in individual behavior can make collective behavior less sensitive to these perturbations and therefore more predictable. We also examined conditions in which collective behavior unexpectedly succeeds despite the group’s weak interest in the outcome. In groups with an otherwise intractable start-up problem, individual randomness can lead to spontaneous instigation, making outcomes more sensitive to the strength of collective interests and therefore more predictable. These effects of chance behavior become much more pronounced as group size increases. Although randomness is often assumed to be a theoretically unimportant residual category, our findings point to the need to bring individual idiosyncrasy back into the study of collective behavior.

Postprandial glycaemic responses in women co-ingesting green leafy vegetables with a carbohydrate meal: interactions with the sirtuin system

AbstractThe addition of vegetable to carbohydrate-based meals has been shown to improve postprandial glucose homeostasis. Inter-individual variation in responses preclude conclusive evidence, particularly in women. The sirtuins and associated genes involved in producing the chemical, nicotinamide adenine dinucleotide (NAD), are emerging as key players in blood glucose control and may contribute to variable responses. This study aimed to investigate effects of co-ingesting green leafy vegetables (GLV) on postprandial glucose regulation following a carbohydrate meal and factors affecting inter-individual variation particularly around the sirtuin system.Twenty-five women (BMI 24.8–30.5 kg/m2) were recruited to ‘The impact of Vegetables’ (VegGI) study on acute glycaemia and Glycaemia induced CVD risk in women: metabolic effects and Inter-individual variations. Postprandial glycaemic responses (GR) following rice (75 g of available carbohydrate), rice with bok choy (150g) or spinach (150g) were measured every 5 minutes for 4 hours using a Continuous Glucose Monitoring system (Medtronic Ltd). Anthropometric, cholesterol (Cholestech LDX, Alere), HbA1c (Afinion AS100, Alere) and insulin (Mercodia AB) measures were made in a fasted state. Oestradiol, progesterone, follicular stimulating hormone and testosterone were measured (ADVIA Centaur). Total RNA was extracted from postprandial blood collected at 0 h, 30 min, 1 h and 2 h in PAXgene blood RNA tubes (PreAnalytiX GmbH) using a Blood RNA Kit (Qiagen, Crawley, UK) and quality assessed by Agilent Bioanalyser (Agilent Technologies, Bracknell, UK). Gene expression was measured using the GenomeLab System and a custom designed multiplex assay, the hSIRTNADPlex (25 targets involved in the sirtuin signalling).Linear mixed models (ver.24.0; SPSS Inc) revealed no effect of GLV consumption on postprandial GR. Principal component analysis (SIMCA-P + 12.0 software, MKS Instruments UK Ltd.) of postprandial GR indicated inter-individual variation in the responses associated with the test meals. Partial Least Square (PLS) stratified the cohort into two subgroups based on sirtuin system gene expression profiles. Postprandial GR was a contributing factor in the stratification observed, together with BMI, plasma lipid, insulin and glucose levels, but not menopausal status.Preliminary evidence indicates that co-ingesting GLV with a carbohydrate meal does not reduce postprandial GR in women (BMI 24.8–30.5 kg/m2) and that significant inter-individual variation in postprandial GR may be linked to the sirtuin system, BMI, plasma lipid, insulin, and glucose levels but not menopausal status. Recruitment and data analysis are ongoing to increase group size and further assess contributing factors.This work was supported by Scottish Government's Rural and Environment Science and Analytical Services Division

Vigilance behaviour in Siberian ibex (Capra sibirica): Effect of group size, group type, sex and age

Gregarious prey species modify their behaviours in response to predation risk in two ways: by increasing vigilance level or enlarging herd size. However, individuals of various sex and age have different responses to the same danger, and even the same individuals react differently depending on their status during biological events or within group types. But how these factors influence the interactions between vigilance level and group size is still poorly understood. Therefore, we studied this phenomenon by observing and analyzing the behaviours of the Siberian ibex (Capra sibirica) in the Eastern Tian-Shan Mountains (China). We found that similar to many other gregarious ungulates, Siberian ibex demonstrated a decrease in vigilance level with an increase in group size, since staying in larger groups increased the probability of predator detection and reduced the possibility of being captured. In general, males were more vigilant than females during the rut due to the sharp increase in their social alertness to achieve greater success in reproduction. In contrast, females were more vigilant than males out of rutting time, particularly significantly following parturition, since mothers spent a lot of their energy in maternal care, which coupled with having small and unexperienced newborns, made them more vulnerable to predation than other conspecifics. Siberian ibex had the same vigilance level in summer and winter, because of seasonally opposite trade-offs between feeding duration and vigilance level based on seasonal changes in food availability. Individuals in mixed-sex and female groups were more often targeted by predators, prompting individuals from these groups to be more vigilant than in male groups. The vigilance level in males decreased with age likely because of their increased body size and enhanced vigilance experience, which reduced their risk of predation. Our study confirmed that the Siberian ibex’ vigilance level inversely correlated with group size, but other various factors, such as forage biomass/quality, sex, biological cycle, group types and age, had significant impacts on their interrelationship.

Modeling active sensing reveals echo detection even in large groups of bats

Active sensing animals perceive their surroundings by emitting probes of energy and analyzing how the environment modulates these probes. However, the probes of conspecifics can jam active sensing, which should cause problems for groups of active sensing animals. This problem was termed the cocktail party nightmare for echolocating bats: as bats listen for the faint returning echoes of their loud calls, these echoes will be masked by the loud calls of other close-by bats. Despite this problem, many bats echolocate in groups and roost socially. Here, we present a biologically parametrized framework to quantify echo detection in groups. Incorporating properties of echolocation, psychoacoustics, acoustics, and group flight, we quantify how well bats flying in groups can detect each other despite jamming. A focal bat in the center of a group can detect neighbors in group sizes of up to 100 bats. With increasing group size, fewer and only the closest and frontal neighbors are detected. Neighbor detection is improved by longer call intervals, shorter call durations, denser groups, and more variable flight and sonar beam directions. Our results provide a quantification of the sensory input of echolocating bats in collective group flight, such as mating swarms or emergences. Our results further generate predictions on the sensory strategies bats may use to reduce jamming in the cocktail party nightmare. Lastly, we suggest that the spatially limited sensory field of echolocators leads to limited interactions within a group, so that collective behavior is achieved by following only nearest neighbors.

Firm performance in networks: The interplay between firm centrality and corporate group size

Corporate groups or networks, which are defined as collections of two or more legally independent firms connected through ownership ties, are prevalent in both developed and developing countries. The separate effects of firm centrality and corporate group size on firm performance have been largely discussed in the literature. However, the effect of their interaction remains underexplored. This paper attempts to fill the gap by introducing a new normalized measure of firm centrality independent of corporate group size. Our empirical analysis is based on a set of global corporate networks encompassing 17.8 million firms and the ownership ties between them extracted from the ORBIS database in 2014. We further investigate the firm performance in the corporate networks above by gathering financial information on 483,835 Italian firms from the AIDA database from 2014 to 2016. We find a positive relationship between firm centrality and firm performance, but the significance of the relationship decreases as corporate group size increases.

Evaluation of an Elk Detection Probability Model in the Black Hills, South Dakota

Since 1993, elk (Cervus canadensis nelsoni) abundance in the Black Hills of South Dakota has been estimated using a detection probability model previously developed in Idaho, though it is likely biased because of a failure to account for visibility biases under local conditions. To correct for this bias, we evaluated the current detection probability across the Black Hills during January and February 2009–2011 using radio-collared elk. We used logistic regression to evaluate topographic features, habitat characteristics, and group characteristics relative to their influence on detection probability of elk. Elk detection probability increased with less vegetation cover (%), increased group size, and more snow cover (%); overall detection probability was 0.60 (95% CI 0.52–0.68), with 91 of 152 elk groups detected. Predictive capability of the selected model was excellent (ROC = 0.807), and prediction accuracy ranged from 70.2% to 73.7%. Cross-validation of the selected model with other population estimation methods resulted in comparable estimates. Future applications of our model should be applied cautiously if characteristics of the area (e.g., vegetation cover >50%, snow cover >90%, group sizes >16 elk) differ notably from the range of variability in these factors under which the model was developed.

Larger group sizes facilitate the emergence and spread of innovations in a group-living bird

The benefits of group living have traditionally been attributed to risk dilution or the efficient exploitation of resources; individuals in social groups may therefore benefit from access to valuable information. If sociality facilitates access to information, then individuals in larger groups may be predicted to solve novel problems faster than individuals in smaller groups. Additionally, larger group sizes may facilitate the subsequent spread of innovations within animal groups, as has been proposed for human societies. We presented a novel foraging task (where a food reward could be accessed by pushing a self-shutting sliding door) to 16 groups of wild, cooperatively breeding Australian magpies, Cracticus tibicen dorsalis, ranging in size from two to 11 individuals. We found a nonlinear decline in the time taken for the innovative behaviour to emerge with increasing group size, and social information use facilitated the transmission of novel behaviour, with it spreading more quickly in larger than smaller groups. This study provides important evidence for a nonlinear relationship between group size and the emergence of innovation (and its subsequent transmission) in a wild population of animals. Further work investigating the scope and strength of group size–innovation relationships, and the mechanisms underpinning them, will help us understand the potential advantages of living in larger social groups.