The Evolution of Animal Communication: Reliability and Deception in Signaling Systems. William A. Searcy and S. Nowicki

Among Darwin’s brilliant ideas was his (1871) conception of animal communication signals as adaptive characteristics of a species. The idea was subsequently taken up by the ethologists of Europe in the 1930s (Lorenz, Tinbergen, and von Frisch in particular) in their studies of animal signaling systems in nature. For many subsequent researchers, human language was the implicit model for an animal communication system. Although not expecting the same level of complexity, these researchers assumed that animal signals transmitted information from sender to receiver that was honest, and that benefitted them both. However, the honest signaling/mutual benefit view was challenged by new researchers steeped in the sociobiology and behavioral ecology movement of the 1960s. The emphasis on competition in this new field inspired these researchers to reconceive the animal signaling process as one in which the sender manipulates the receiver to the sender’s advantage. This view was challenged in turn when researchers recognized that the receiver was not a passive party in the interaction, but fully capable of manipulating the sender to its advantage. The communication interaction can be viewed as an arm’s race. The handicap principle—the idea that honesty in signaling can be maintained if signals are costly—is one way the receiver may gain an edge in this competition. Eventually, game theory considerations led to the development of a revised perspective in which signals evolve only when both the sender and the receiver benefit on average, and where signals are honest on average. Researchers examining a particular signaling system’s signals these days ask not are the signals honest, but how reliable are the signals.

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Bioluminescent backlighting illuminates the complex visual signals of a social squid in the deep sea

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1920875117 ◽

2020 ◽

Vol 117 (15) ◽

pp. 8524-8531 ◽

Cited By ~ 1

Author(s):

Benjamin P. Burford ◽

Bruce H. Robison

Keyword(s):

Deep Sea ◽

Animal Communication ◽

Deep Ocean ◽

Visual Signals ◽

Entire Body ◽

Limited Information ◽

Dosidicus Gigas ◽

Low Light ◽

Signaling Systems ◽

Humboldt Squid

Visual signals rapidly relay information, facilitating behaviors and ecological interactions that shape ecosystems. However, most known signaling systems can be restricted by low light levels—a pervasive condition in the deep ocean, the largest inhabitable space on the planet. Resident visually cued animals have therefore been hypothesized to have simple signals with limited information-carrying capacity. We used cameras mounted on remotely operated vehicles to study the behavior of the Humboldt squid, Dosidicus gigas, in its natural deep-sea habitat. We show that specific pigmentation patterns from its diverse repertoire are selectively displayed during foraging and in social scenarios, and we investigate how these behaviors may be used syntactically for communication. We additionally identify the probable mechanism by which D. gigas, and related squids, illuminate these patterns to create visual signals that can be readily perceived in the deep, dark ocean. Numerous small subcutaneous (s.c.) photophores (bioluminescent organs) embedded throughout the muscle tissue make the entire body glow, thereby backlighting the pigmentation patterns. Equipped with a mechanism by which complex information can be rapidly relayed through a visual pathway under low-light conditions, our data suggest that the visual signals displayed by D. gigas could share design features with advanced forms of animal communication. Visual signaling by deep-living cephalopods will likely be critical in understanding how, and how much, information can be shared in one of the planet’s most challenging environments for visual communication.

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Separating noise and function in systems of animal communication: a comparative study of aggressive signaling in crayfish

10.1101/2020.08.03.234419 ◽

2020 ◽

Author(s):

Zackary A. Graham ◽

Michael J. Angilletta

Keyword(s):

Animal Communication ◽

Freshwater Crayfish ◽

Biological Noise ◽

Signaling System ◽

Functional Variation ◽

Physiological Noise ◽

Signaling Systems ◽

Statistical Property ◽

And Function ◽

Relative Body Size

ABSTRACTA primary issue in the study of dishonest signaling is the researcher’s ability to detect and describe a signal as being dishonest. However, by understanding the relative honesty of a signal as a statistical property of an individual or population, researchers have recently quantitively describe dishonest communication. Thus, dishonesty signals can be understood as when there is a breakdown in the correlation between a signal and its underlying meaning; creating variation within a signaling system. However, such variation in signaling systems may not be attributed to dishonesty, because of inherent noise within biological systems driven by evolutionary or physiological noise. Here, we try to separate out functional variation within honest or dishonesty signaling systems from inherent biological noise by leveraging homologous structures that have evolved for separate functions – the enlarged claws of freshwater crayfish. Because burrowing species of freshwater crayfish claws have not evolved as signals, the variability in the size and strength of their claws should be minimal when compared to claws of non-burrowing species that evolved as signals during aggression. We found that despite the claws of burrowing and nonburrowing crayfish claws having evolved to serve difference functions, the claws of all species in our study were inherently noisy. Furthermore, although claws that unreliably correlate to the strengthen the wielder may function as dishonest signals in other crustaceans, we did not find support for this hypothesis; because crayfish escalated aggression based on relative body size.

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The Rain Calls of Frogs and the Reigning Paradigm of American Herpetology

Archives of Natural History ◽

10.3366/anh.2020.0649 ◽

2020 ◽

pp. 1-35

Author(s):

Gordon L. Miller

Keyword(s):

Twentieth Century ◽

Animal Communication ◽

The United States ◽

Emotional States ◽

Breeding Sites ◽

Gradual Disappearance ◽

The Times ◽

Traditional Natural ◽

Breeding Seasons ◽

The Comparative Study

American zoologists and herpetologists during the past fifty years have successfully deciphered the mating calls of frogs and toads with ever increasing precision and sophistication. However, the vocalizations most commonly termed “rain calls,” which typically occur beyond both normal breeding seasons and breeding sites, have remained a persistent puzzle. This article traces the gradual disappearance of rain calls, along with a corresponding decline in any mention of emotional states, from herpetological studies of anuran vocalizations in the United States from the middle of the twentieth century to the present and examines the historical roots of this disappearance. This evaporation of rain calls is indicative of a much larger change in the scientific climate of the times involving the transition from traditional natural history to the Neo-Darwinian, adaptationist paradigm of contemporary biology. Rain calls thus increasingly became anomalous, thereby eliminating a possibly fruitful line of inquiry in the comparative study of human-animal communication, in this case with evolution's earliest vocalizers. The contours and benefits of a more encompassing paradigm, envisioned by some leading early twentieth-century zoologists, are briefly discussed.

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