Compression principle and Zipf’s Law of brevity in infochemical communication

Abstract

Compression has been presented as a general principle of animal communication. Zipf’s Law of brevity is a manifestation of this postulate and can be generalized as the tendency of more frequent communicative elements to be shorter. Previous works supported this claim, showing evidence of Zipf’s Law of brevity in animal acoustical communication and human language. However, a significant part of the communicative effort in biological systems is carried out in other transmission channels, such as those based on infochemicals. To fill this gap, we seek, for the first time, evidence of this principle in infochemical communication by analysing the statistical tendency of more frequent infochemicals to be chemically shorter and lighter. We analyse data from the largest and most comprehensive open-access infochemical database known as Pherobase, recovering Zipf’s Law of brevity in interspecific communication (allelochemicals) but not in intraspecific communication (pheromones). Moreover, these results are robust even when addressing different magnitudes of study or mathematical approaches. Therefore, different dynamics from the compression principle would dominate intraspecific chemical communication, defying the universality of Zipf’s Law of brevity. To conclude, we discuss the exception found for pheromones in the light of other potential communicative paradigms such as pressures on successful communication or the Handicap principle.

Direct and indirect evidence of compression of word lengths. Zipf’s law of abbreviation revisited

“…A salient case is Zipf's law of abbreviation, the tendency of more frequent words to be shorter (Zipf, 1949). It holds across language families (Bentz and Ferrer-i-Cancho, 2016;Koplenig et al, 2022;Levshina, 2022;Meylan and Griffiths, 2021;Piantadosi et al, 2011), writing systems (Sanada, 2008;Wang and Chen, 2015) and modalities (Börstell et al, 2016;Hernández-Fernández and Torre, 2022;Torre et al, 2019), and also when word length in characters is replaced by word duration in time (Hernández-Fernández et al, 2019). Furthermore, the number of species where a parallel of this law has been confirmed in animal communication is growing over time (Semple et al, 2022).1 In language sciences, research on the law of abbreviation in languages measures word length in discrete units (e.g., characters) whereas, in biology, research on the law in other species typically uses duration in time.…”