The question of what animals understand about their social worlds is fundamental to studies of the evolution of sociality, cognition, and animal culture. However, the presence and extent of social knowledge in individuals is difficult to detect , and when detections have been made , differences in methodology make cross-species comparisons difficult. We present a new method for detecting social knowledge. This method infers individual-level strategic rules for aggression in dominance hierarchies where rankdifferences between individuals may structure decision-making . We apply this method to a data from 172 social groups across 85 species in 22 orders. By looking for heuristics that depend upon knowledge of group-level facts , we can back-infer the types of knowledge individuals possess . Summary measures  then place groups within a taxonomy, providing a  "social assay" of group-level knowledge. This assay allows the identification of consensus strategies at the group level. The majority of animal groups in our dataset (112 groups, 65\%) follow a downward heuristic  , spreading aggression relatively equally across lower-ranked opponents . An additional 50 groups (29\%) use strategies that are indicative of more detailed rank knowledge. Different groups within the same species can use different strategies, indicating that the choice of heuristics may be contextual and that the structuring of aggression  should not be considered a fixed characteristic of a species . Instead, individuals may be able to plastically respond to changes in environmental or social conditions by changing their strategies. Our approach to studying animal conflict provides new opportunities to investigate the extent of rank knowledge across species , compare the evolution of social knowledge, and better understand the effect of social knowledge on individual behaviour in within-group conflict .
The information contained in social systems, and the part of it that animals actually possess, is a driver of the evolution of sociality, cognition, and animal culture. However, it is difficult to detect how much information individuals actually have about their social worlds. Even when information can be detected , differences in methodology make cross-species comparisons difficult. We present a new method for detecting social information in dominance hierarchies, that infers individual-level rules for aggression based on how aggression decisions are influenced by differences in social rank . We apply this method to 172 social groups across 85 species in 22 orders. By looking for heuristics that depend upon rank information , we can back-infer the types of information individuals possess about the macro-level properties of their group . Summary measures of these heuristics then place groups within a taxonomy, providing a biologically-relevant "social assay" to quantify the amount of social information and to identify consensus strategies at the group level. The majority of animal groups in our dataset (112 groups, 65\%) follow a downward heuristic to structure their fights , spreading aggression relatively equally across lower-ranked opponents but 50 groups (29\%) use strategies that are indicative of more detailed rank information. Strategies are not phylogenetically constrained and groups within the same species can use different strategies, indicating that the choice of heuristics may be contextual and that the structuring of aggression by social information should not be considered a fixed characteristic . Instead, individuals may be able to plastically respond to local conditions by increasing or decreasing the complexity of their strategies. Our approach provides new opportunities to study the use of social information across species and the evolution of social complexity and cognition .
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question of what animals understand about their social worlds is fundamental to studies
information contained in social systems, and the part of it that animals actually possess, is a driver
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the presence and extent of social knowledge in individuals
it
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, and when detections have been made
how much information individuals actually have about their social worlds. Even when information can be detected
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knowledge. This method
information in dominance hierarchies, that
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strategic
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in dominance hierarchies where rankdifferences between individuals may structure decision-making
based on how aggression decisions are influenced by differences in social rank
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a data from
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knowledge of group-level facts
rank information
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knowledge individuals possess
information individuals possess about the macro-level properties of their group
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of these heuristics
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biologically-relevant
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of group-level knowledge. This assay allows the identification of
to quantify the amount of social information and to identify
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to structure their fights
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. An additional
but
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knowledge. Different
information. Strategies are not phylogenetically constrained and
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by social information
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of a species
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changes in environmental or social conditions by changing
local conditions by increasing or decreasing the complexity of
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to studying animal conflict
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investigate the extent of rank knowledge across species , compare
study the use of social information across species and
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knowledge, and better understand the effect of social knowledge on individual behaviour in within-group conflict
complexity and cognition