Animal Cognition最新文献

Many communicative systems have been selected for efficiency, shaped by the trade-off between information transmission and energetic or temporal constraints. Linguistic laws such as Menzerath’s law—predicting shorter elements in longer sequences—have emerged as widespread principles across vocal communication in many species. While these laws have been predominantly studied at the species level, the influence of individual and social factors remain underexplored. In this study, we investigated adherence to Menzerath’s law in the vocal communication of carrion crows, Corvus corone corone, hooded crows, Corvus corone cornix and hybrids. Our findings show that crow call sequences adhere to Menzerath’s law, with shorter calls occurring in longer sequences, demonstrating structural efficiency in vocal communication. In carrion crows specifically, we analysed call sequences in relation to individual characteristics (sex, age) and social variables (group size, dominance status, strength of affiliative relationships). Interestingly, adherence to Menzerath’s law was stronger in females and younger individuals, while no effects were found for group size, dominance, or affiliative relationships. This study provides the first evidence of Menzerath’s law in corvid vocal communication and suggests that individual-level traits, rather than broader social dynamics, may shape vocal efficiency. These findings broaden our understanding of widespread principles in animal communication and raise new questions about the ontogeny and flexibility of vocal efficiency in complex social species.

A recent proposal defines prosociality in terms of intentional behaviour that successfully benefits another. We suggest, however, that prosociality would be better defined more simply in terms of the intention to benefit another, regardless of whether a benefit really occurs, for three reasons: (i) the construct of “benefit” is itself difficult to operationalize, (ii) an intention-based definition is no less conservative than the proposed outcome-based one, and (iii) an outcome-based definition overlooks plausible cases of intended but unsuccessful prosocial actions as well as the psychological consequences of such actions. Amending the working definition of prosociality to be centred on intentions, not outcomes, would make it more useful as a tool for comparative and developmental research.

Spontaneous recovery of choice is a behavioral phenomenon where a delay period (without new experience) elicits the recovery of a preference consistent with a previous distribution of rewards, rather than the most recently experienced distribution of rewards. On short timescales (< 48 h), the occurrence of spontaneous recovery of choice has been effectively predicted by the Temporal Weighting Rule. However, previous study of this phenomenon over longer timescales (> 48 h) has found results inconsistent with model predictions. The present experiments investigated three potential explanations for these results: (1.) whether time’s passage alone causes animals to revert to random exploratory behavior; (2.) whether time’s effect on behavior is moderated by experience of volatility in rewards during training; and (3.) whether a drift toward random exploratory behavior produced by time’s passage can be distinguished from the effect of spontaneous recovery of choice. Subjects experienced varied reward conditions in a concurrent choice procedure before preference between options was evaluated at various test delays. Obtained results ruled out these first two explanations, but were inconclusive in distinguishing the effects of a drift toward random exploratory behavior from the effect of spontaneous recovery of choice. Limitations and directions for further investigation are discussed.

Over recent decades comprehensive catalogues of vocal, facial, and gestural signals have been established for most great ape species; however, a systematic description of wild gorilla gestural behaviour, particularly of the Eastern gorilla species, remains missing. We address this absence by cataloguing the physical form of gestural units used by 49 habituated wild mountain gorillas (Gorilla beringei beringei) from four social units in the Bwindi Impenetrable National Park, Uganda (n = 157 observation days over 8 months). We obtained a dataset of n = 3220 instances of intentional gesture, coded with a systematic ELAN-based framework (GesturalOrigins). Mountain gorillas employed a repertoire of 63 gesture actions, including potentially species-specific units, across 10 behavioural contexts. A latent class analysis on variants of gesture action expression split units further into 126 finer-grained forms (‘morphs’). We observed ~ 6 gestures per hour of observation time and species-level repertoire size was similar to those reported in both Pan species. Our study constitutes the first systematic description of the mountain gorilla gestural repertoire, providing a new understanding of their communication, filling current gaps in great ape gestural phylogeny, and complementing previous studies on their vocal signals. Living in cohesive, small-sized female-male bonded social units, gorillas show striking differences in social organisation as compared to Pan species and provide crucial context for theories on the potential ancestral states of human communicative behaviour.