Jolyon J. Faria

Emergent Sensing of Complex Environments by Mobile Animal Groups

The Power of the Collective Sensing the environment is generally considered to require significant cognitive sampling and comparison, not to mention time. However, species that do not necessarily have the cognitive ability, or the time, have also proven to be quite adept at sensing and evaluating their environment. Berdahl et al. (p. 574) show that in shiners, a species of schooling fish, mere attraction to, and movement toward, neighboring individuals allows the group to track preferred darkness in a variable-light environment. Living in a group amplifies the reach of an individuals capacity to sense environmental changes. The capacity for groups to exhibit collective intelligence is an often-cited advantage of group living. Previous studies have shown that social organisms frequently benefit from pooling imperfect individual estimates. However, in principle, collective intelligence may also emerge from interactions between individuals, rather than from the enhancement of personal estimates. Here, we reveal that this emergent problem solving is the predominant mechanism by which a mobile animal group responds to complex environmental gradients. Robust collective sensing arises at the group level from individuals modulating their speed in response to local, scalar, measurements of light and through social interaction with others. This distributed sensing requires only rudimentary cognition and thus could be widespread across biological taxa, in addition to being appropriate and cost-effective for robotic agents.

Behavioural trait assortment in a social network: patterns and implications

The social fine structure of a population plays a central role in ecological and evolutionary processes. Whilst many studies have investigated how morphological traits such as size affect social structure of populations, comparatively little is known about the influence of behaviours such as boldness and shyness. Using information on social interactions in a wild population of Trinidadian guppies (Poecilia reticulata), we construct a social network. For each individual in the network, we quantify its behavioural phenotype using two measures of boldness, predator inspection tendency, a repeatable and reliably measured behaviour well studied in the context of co-operation, and shoaling tendency. We observe striking heterogeneity in contact patterns, with strong ties being positively assorted and weak ties negatively assorted by our measured behavioural traits. Moreover, shy fish had more network connections than bold fish and these were on average stronger. In other words, social fine structure is strongly influenced by behavioural trait. We assert that such structure will have implications for the outcome of selection on behavioural traits and we speculate that the observed positive assortment may act as an amplifier of selection contributing to the maintenance of co-operation during predator inspection.

Swarm intelligence in humans: diversity can trump ability

We identify some of the possibilities and limitations of human swarm intelligence (SI) using the response of the public to two types of cognitive problems. Furthermore, we propose a simple measure for the quantification of collective information that could form the basis for SI in study populations for specific tasks. Our three main results are (1) that the potential benefits of SI depend on the type of problem, (2) that individual performance and collective performance can be uncorrelated and that a group of individually high performers can be outcompeted by a same-size group of individually low performers, and (3) that adding diversity to a group can be more beneficial than adding expertise. Our results question the emphasis that societies and organizations can put on individual performance to the detriment of diversity as far as teams are concerned. Nevertheless, it is important to point out that while diversity is a necessary condition for effective SI, diversity alone is clearly not sufficient. Finally, we discuss the potential implications of our findings for the evolution of group composition and the maintenance of personality diversity in animals.

Navigation in human crowds; testing the many-wrongs principle

The ‘many-wrongs principle’ predicts that animal group cohesion can cause groups to navigate more accurately than singletons. Recent theoretical work using individual-based simulations and several empirical studies of bird flock behaviour support this principle. However, for real animal groups it remains unclear what key factors are involved and whether group cohesion alone can act to produce the effect. We tested model predictions using human participants in a large circular arena. They were tested alone and in groups of two, three, six and 10, in three trials. For each trial, individuals were instructed to stay together and approach a preset but unmarked target on the arena perimeter. The target instruction included a degree of directional uncertainty of 22.5°, 67.5° or 112.5°. Individual directional uncertainty was equal for each group member within a trial, but differed between trials. As expected, we found that groups comprising individuals with lower directional uncertainty navigated more accurately. Group navigational accuracy increased with group size but only between singletons and groups of 10 and only when individuals had a high directional uncertainty of 112.5°. This study provides evidence in human groups that group cohesion can increase navigational accuracy but that this effect is restricted to larger group sizes and when individual directional uncertainty is high.

Kin assortment in juvenile shoals in wild guppy populations

Grouping provides many potential benefits to individuals in terms of foraging and anti-predator protection. However, it has been suggested that individuals could gain additional benefits in terms of indirect fitness by grouping with kin. Surprisingly, the genetic composition of wild fish shoals and the importance of kin-associated shoaling remain poorly understood. The Trinidadian guppy (Poecilia reticulata) has life history traits that might promote kin structure of shoals such as internal fertilisation and small brood size in contrast to many other fish species. Even though previous studies did not find any indication of kin structure in shoals of adult guppies, it is possible that related juveniles remain together in shoals, partly because of lower mobility and because the advantages of kin association may change with age. Using 10 microsatellite markers, we conducted a genetic analysis on 40 shoals from four populations. Pair-wise relatedness was inferred using a modified version of the software package COLONY and permutation tests were conducted to test the hypothesis that kin occur together in juvenile shoals more often than expected by chance. The frequency of sib dyads among juveniles within shoals was significantly larger than that between shoals in two high predation populations but not in two low predation populations. This finding contributes to the understanding of factors underlying shoal composition and highlights the potential of recent methodological advances for detecting such relationships.

Does defection during predator inspection affect social structure in wild shoals of guppies

Reciprocal altruism has been proposed as a possible mechanism for the evolution of cooperative behaviour. However, very few investigations have tested predictions of reciprocity in wild animal populations. In the current investigation we simulated defection during predator inspection in a wild population of guppies, Poecilia reticulata. Two experiments were run: the first simulating defection during a single exposure to a predator and the second during multiple exposures to a predator. We then compared subsequent social and cooperative interactions with those observed prior to the treatments. From theory and previous experiments on cooperation and reciprocity, we predicted that defection would result in a reduction in social and cooperative interactions during subsequent predator inspections. However, our experiments did not find any effect of simulated defection(s) on the subsequent social structure, or on patterns of predator inspection behaviour. We discuss the potential reasons for the observed results and suggest future directions for research to address mechanisms underpinning the nature of cooperative interactions during predator inspection.

Collective cognition in humans: groups outperform their best members in a sentence reconstruction task.

Group-living is widespread among animals and one of the major advantages of group-living is the ability of groups to solve cognitive problems that exceed individual ability. Humans also make use of collective cognition and have simultaneously developed a highly complex language to exchange information. Here we investigated collective cognition of human groups regarding language use in a realistic situation. Individuals listened to a public announcement and had to reconstruct the sentence alone or in groups. This situation is often encountered by humans, for instance at train stations or airports. Using recent developments in machine speech recognition, we analysed how well individuals and groups reconstructed the sentences from a syntactic (i.e., the number of errors) and semantic (i.e., the quality of the retrieved information) perspective. We show that groups perform better both on a syntactic and semantic level than even their best members. Groups made fewer errors and were able to retrieve more information when reconstructing the sentences, outcompeting even their best group members. Our study takes collective cognition studies to the more complex level of language use in humans.