Many animals produce courtship sounds, and receivers prefer some sounds over others. Shared ancestry and convergent evolution may generate similarities in preference across species and underlie Darwin's conjecture that some animals "have nearly the same taste for the beautiful as we have." In this study, we show that humans share acoustic preferences with a range of animals, that the strength of human preferences correlates with that in other animals, and that humans respond faster when in agreement with animals. Furthermore, we found greatest agreement in preference for adorned, ancestral, and lower-frequency sounds. Humans' music listening experience was associated with preferences. These results are consistent with theories arguing that biases in processing sculpt acoustic preferences, and they confirm Darwin's century-old hunch about the conservation of aesthetics in nature.

Many animals form behavioral collectives, and optimal interaction strategies often differ across social contexts. Sensory scenes generated by many interacting conspecifics are complex. Thus, maintaining socially calibrated responses requires individuals to distill key features from conspecific scenes to guide continued adjustments to social fluctuations. Túngara frogs produce mating calls in choruses varying in size, and interaction patterns differ across social environments; rivals alternate their calls in smaller choruses, but increasingly overlap one another's calls in a stereotyped fashion as chorus size increases. We used automated playback to investigate the cues guiding this socially mediated shift in interaction modes. We played conspecific stimulus calls to males at various delays relative to their own calls, preceded by various acoustic motifs that mimicked conspecific stimulation patterns males will hear in different social environments. Males almost never overlapped isolated stimulus calls at any delays. However, their probabilities of overlapping stimulus calls increased markedly when stimulus calls were preceded by motifs characteristic of larger choruses, i.e. those exhibiting intense conspecific stimulation patterns. Furthermore, the escalatory effects of motifs became increasingly pronounced as motif/stimulus combinations were played at later delays. Thus, interaction strategies are calibrated to current social dynamics each call cycle in response to a multifaceted cue that incorporates both the nature of conspecific stimulation experienced and how the timing of this stimulation interacts with endogenous responsiveness rhythms. Our results highlight that inactive phases within behavioral rhythms provide repeated opportunities to sample current social dynamics, allowing response patterns to be continually calibrated to social fluctuations in behavioral collectives.

Abstract Collective animal behavior occurs in high-stakes contexts where failing to coordinate effectively with group-mates can spell disaster for individuals. Yet, identifying instances of coordination failure is challenging, meaning their evolutionary effects remain mysterious. Synchronous calls in alternating frog choruses (i.e., inadvertent signal collisions) are unambiguous failure events that impose steep attractiveness costs. We modeled túngara frog chorusing dynamics to reveal the sensorimotor and social mechanisms underpinning synchrony. Ultimately, inter-male variation in two key sensorimotor attributes, the periods of male calling rhythms and call latencies, generated divergent synchrony engagement patterns. Modeling female preferences revealed that these varied behavioral outcomes then yielded disparate attractiveness consequences. By mechanistically linking the causes and consequences of coordination failure, we demonstrate that non-random failure patterns in collectives generate selection gradients that refine sensorimotor tuning.

The human larynx, compared to those of closely related primates, lies deeper in the throat and lacks vocal membranes and air sacs. These shifts are usually analyzed regarding their acoustic effects on vowel-like vocalizations, since the evolution of speech was long thought to require an expansion of vocal range driven by vocal tract modifications. However, vowels are just one type of phoneme, and speech is just one class of human utterance. To understand the evolutionary underpinnings of known shifts in human vocal morphology, a broader bioacoustic comparison is needed. Specifically, the range of sounds used in human speech must be compared to that employed in other human vocalizations and in the repertoires of extant close primate relatives. Here, we measure the acoustic-feature space occupied by human speech, non-linguistic, and musical vocalizations along with the calls of chimpanzees, bonobos, and chacma baboons. We use Mel-frequency cepstral coefficients to create an acoustic space depicting the spectro-temporal features of over 750,000 brief vocal segments sourced from published databases and other verified sources. Speech and song occupied significantly less volume in this acoustic space than human non-linguistic vocalizations. In addition, the acoustic-feature volumes of speech and song were not statistically distinct from those of non-human primates. These results suggest that speech was not enabled by an expansion of human vocal acoustic space. Anatomical shifts unique to humans may have led to an elaboration of non-linguistic utterances, but learned vocalizations use a surprisingly small fraction of this space. Our understanding of human vocal evolution will be further informed by additional systematic comparisons of the function and homology of non-speech vocalizations, along with the collection and incorporation of more complete non-human primate vocal datasets, especially from Gorilla and Orangutan.

Male t & uacute;ngara frogs appear in choruses and have well-defined vocal cords at a size of 19 mm snout-vent length (SVL), but they do not begin producing advertisement calls until they reach approximately 24 mm SVL. Is this because the larynx is not fully mature until the latter point, or is it because the calls of small-bodied adults would not be attractive enough to outweigh the costs (energy, predation and parasitism) of producing them? We investigate this question by tuning bond graph models of the t & uacute;ngara frog larynx with parameter values across this critical body size range. Simulations were informed by a new set of diceCT-based measurements of key laryngeal morphological features from an ontogenetic series. Models produce sustained oscillations in airflow through the larynx (sound) with species-typical spectral features across the full range of the ontogenetic 'silent zone', suggesting that muteness during this period is facultative and not physically enforced. This result illuminates the morphological and behavioural consequences of an interplay of natural and sexual selection. Sexual selection and developmental constraints may lead the early development of laryngeal vibratory tissues, while natural selection (energetic costs and predation avoidance) and sexual selection (reduced call attractiveness) act to mute smaller adult frogs.

To attract mates, organisms relying on advertisement signals must encode relevant information and transmit it to target receivers, yet the effectiveness of this process is mediated by the environment. The acoustic adaptation hypothesis (AAH) proposes that habitat properties impose selective forces on acoustic signal design to enhance transmission efficiency. In tropical forests, pronounced vertical heterogeneity in microhabitats creates a variety of conditions for signalers, raising the question of how calling height influences signal transmission efficiency across forest strata. To investigate how vertical microhabitat variation modulates signal transmission, we experimentally broadcast the advertisement calls of 24 species from a Neotropical anuran community from both the understory and the relatively understudied dimension of the forest, the canopy. Across species, calls showed lower transmission performance in the canopy than in the understory, regardless of the species' natural calling height. The transmission performance did not consistently differ among species occupying different vertical strata, nor did it align with the predictions from the AAH. Although our results are inconsistent with AAH, they suggest that habitat properties that vary with height, such as vegetation architecture and background noise, likely modulate signal transmission, increasing excess attenuation, degradation, and reverberation. This study emphasizes that the complex nature of vertical forest microhabitats may affect signal transmission in different forest types and sensory modalities, ultimately modulating the evolution of signal design.

Asexual species, despite lacking recombination, can evolve in response to environmental changes and influence the evolutionary trajectory of coexisting sexual species. Gynogenesis, where asexual females rely on sperm from males of a different species, offers a unique perspective on the eco-evolutionary dynamics between asexual females and their sexual hosts. The Amazon molly, Poecilia formosa, is a gynogenetic species that primarily uses sperm from two sympatric sexual species: the sailfin molly (P. latipinna) and the Atlantic molly (P. mexicana). To understand shape variation in an asexual species relative to their sexual hosts, we analysed shape variation among wild Amazon mollies and their sexual hosts. We tested three hypotheses: (i) Amazon mollies mimic their sexual hosts to enhance mating opportunities (sexual mimicry hypothesis); (ii) ecological interactions or male mate choice drive morphological divergence (character displacement hypothesis); and (iii) Amazon mollies exhibit random shape variation due to their asexual nature (null hypothesis). Our findings revealed significant shape variation in Amazon mollies, which differ from their sexual hosts in a host-specific manner (e.g. Amazon mollies with P. latipinna resemble P. mexicana and vice versa), supporting character displacement at the interspecific level in a sexual-asexual system.

Decision making has important fitness consequences in domains as varied as foraging, mating and predator avoidance. In noisy ecosystems, animals often inform their decisions via information streams that may span sensory modalities. Despite theoretical predictions, we have little understanding of whether attending to multiple cues enhances decision-making performance or reduces it by creating cognitive overload. The predatory fringe-lipped bat, Trachops cirrhosus, hunts by eavesdropping on auditory prey cues, but it utilizes information from other sensory modalities when challenged in the laboratory and rapidly adopts new hunting behaviours through social learning. When hunting frogs, it uses their calls to identify palatable species. T & uacute;ngara frog, Engystomops pustulosus, males court females with a multimodal display: their calls (auditory) and the simultaneously inflating vocal sac (visual) create water ripples (seismic). Here we evaluated decision making in fringe-lipped bats attending to ambiguous stimuli with and without additional cues. We quantified foraging decisions in response to synthesized hybrid calls spanning a gradient from calls of the palatable t & uacute;ngara frog to those of a poisonous toad. Hybrid calls were presented to bats in silence and with additional stimuli: social cues (conspecific chewing noises), environmental noise (anuran chorus) and additional cues associated with target frog calls (vocal sac motion and water ripples). We predicted (1) social and target cues would make hybrid calls more attractive as a potential food source and (2) decision making would be slower in the presence of noise. Counter to expectation, bats maintained highly consistent responses to hybrid stimuli regardless of treatment, supporting neither the enhanced performance hypothesis nor the cognitive overload hypothesis on decision making. We observed flexibility in minimum approach thresholds, however. Bats showed greater exploratory and risk-taking behaviour when given access to information in the form of target cues in noise. Our results elucidate how cognitively complex animals deal with information complexity in varying decision-making contexts. (c) 2025 The Authors. Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/li censes/by-nc-nd/4.0/).

An animal's internal state can shift its behavior. Animals that would typically avoid dangerous foraging conditions may choose to forego safety when food is restricted. Furthermore, physiological demands such as gravidness can drive sex differences in foraging behavior among individuals of the same species. In bats, moonlight can impose risk: some bat species decrease or completely avoid foraging on full moon nights when visually oriented predators are most active. In this study, we tested the hypothesis that hunger increases risky foraging behavior. Previous work with the Jamaican fruit bat, Artibeus jamaicensis, demonstrated that this species shifts its foraging behavior in moonlight by increasing latency to land. In this experiment, bats trained to feed from a food platform were then observed landing in conditions of satiation and food-restriction, with and without the presence of artificial full moonlight. As predicted, we found that bats forage significantly more quickly when food-restricted than when satiated. We found that bats showed a nonsignificant trend to avoid moonlight via increased latencies to land on the food platform. Males-but not females-were significantly slower to land in the presence of moonlight when satiated but not when food-restricted. Our results demonstrate that internal state influences foraging decisions, with individuals landing faster when hungry than when satiated, but that the increased foraging risks associated with moonlight affect male bats more than females. Animals may forego antipredator behaviors if they are hungry. We show that the hunger state in animals can influence feeding decisions in risky environments but only for one sex. In Jamaican fruit bats, we found sex differences in moonlight avoidance when bats were well-fed, where male bats were more cautious to approach a risky food source than female bats. However, when bats had limited food access, we saw these sex differences disappear.

Males of many insect and anuran species send courtship calls to females from within crowded chorusing aggregations. Despite large phylogenetic distances between insects and frogs, many convergences in communication behavior are evident due to similar selection pressures arising when competing acoustically within choruses. Consequently, mechanistic call-timing models and theoretical frameworks originally derived from work on synchronizing insects have been applied fruitfully to alternating frogs. However, despite such similarities, there exist extensive differences in the details of the communication ecologies and nervous systems of these taxa, suggesting interesting differences may have been overshadowed by these broad similarities. Here, we synthesize recent findings regarding the call-timing mechanisms of túngara frogs, a species showing flexible calling interaction patterns across varied chorusing environments. Based on these findings, and hints present in other frogs, we suggest that the unique demands arising within the dense choruses frogs form have selected for call-timing mechanisms whose parameters are highly flexible, and malleable moment-to-moment in response to complex stimulation patterns arising in varied acoustic environments. Such fine-scale malleability and responsiveness to external stimulation are neglected in traditional theoretical models of call-timing mechanisms, possibly because the resulting variability would be detrimental to the highly structured interaction patterns of the synchronizing insects from which much of this work derives. Though further experiments are needed to fully vet our broader claims, we hope to inspire researchers to consider previously neglected factors influencing call-timing responses and chorusing dynamics, and to complement the impressive work on similarities across chorusing taxa with additional details on finer differences.

When vocalizing, many animals engage in decision-making processes that integrate information regarding the current social context. The midbrain dopaminergic system may provide a conserved mechanism underlying this process. For instance, in songbirds, modulation of dopamine release appears to contribute to social context-dependent changes to song. However, relatively little is known about the degree to which dopamine may contribute to similar vocal production and decision-making processes in other taxa, particularly the highly vocal anurans (frogs and toads). Here, we treated wild-caught male túngara frogs (Engystomops pustulosus) with a general dopamine agonist (apomorphine) and assessed its effects on motor performance and motivation as well as vocal decision-making in response to auditory stimuli that varied in social relevance. We found that the dopamine agonist generally increased vocal speed, with decreases in response latencies and call durations. Additionally, we found that dopamine increased call complexity, but only in response to the most socially relevant auditory stimulus (conspecific call). Finally, dopamine treatment and auditory stimulus interacted to affect decision-making regarding call timing and overlap with the stimulus. Compared to controls, frogs with apomorphine were more likely to overlap the playback stimulus in a manner predicted to be more attractive to females. These results highlight a role of dopaminergic circuits in modulating vocal outputs based on social inputs within a species of basal tetrapod.

Sexual selection drives the evolution of a broad diversity of traits, such as the enlarged claws of fiddler crabs, the high-energy behavioral displays of hummingbirds, the bright red plumage of house finches, the elaborated antennae of moths, the wing "snapping" displays of manakins and the calculated calls of túngara frogs. A majority of work in sexual selection has aimed to measure the magnitude of these traits. Yet, we know surprisingly little about the physiology shaping such a diversity of sexually selected behavior and supportive morphology. The energetic properties underlying sexual signals are ultimately fueled by metabolic machinery at multiple scales, from mitochondrial properties and enzymatic activity to hormonal regulation and the modification of muscular and neural tissues. However, different organisms have different physiological constraints and face various ecological selection pressures; thus, selection operates and interacts at multiple scales to shape sexually selected traits and behavior. In this perspective piece, we describe illustrative case studies in different organisms to emphasize that understanding the physiological and energetic mechanisms that shape sexual traits may be critical to understanding their evolution and ramifications with ecological selection. We discuss (1) the way sexual selection shapes multiple integrated components of physiology, behavior, and morphology, (2) the way that sexually selected carotenoid pigments may reflect some aspects of cellular processes, (3) the relationship between sexually selected modalities and energetics, (4) the hormone ecdysone and its role in shaping sex-specific phenotypes in insects, (5) the way varied interaction patterns and social contexts select for signaling strategies that are responsive to social scenes, and (6) the role that sexual selection may have in the exploitation of novel thermal niches. Our major objective is to describe how sexually selected behavior, physiology, and ecology are shaped in diverse organisms so that we may develop a deeper and more integrated understanding of sexual trait evolution and its ecological consequences.

Predators use prey-emitted cues to assess and localize potential food sources. Sexual advertisement calls offer conspicuous cues for eavesdropping predators. While the ontogeny of predatory behaviour is key for survival and can determine adult responses, our understanding of the development of the responses to prey-emitted cues is limited. Here, we measured the responses of juvenile and adult fringe-lipped bats ( Trachops cirrhosus ) to the acoustic advertisement calls of co-occurring anurans. We confirmed that adult bats modulate their foraging behaviour based on their prey’s acoustic cues associated with prey palatability. The responses of juvenile bats revealed that ontogeny plays an important role in bat predatory responses. In contrast to adults, prey palatability did not predict predatory behaviour in juveniles, which responded strongly to poisonous toads and little to some palatable frog species, suggesting that avoidance of poisonous species is learned through experience. Despite these differences, both juveniles and adults appeared to attend to acoustic cues related to body size. Our results support the hypothesis that, over development, acoustic preferences of eavesdropping predators become more closely aligned with advantageous foraging outcomes. Overall, these results offer the first evidence of developmental changes refining decision-making in an eavesdropping predator in the wild.

Recent calls for pluralistic alignment of Large Language Models (LLMs) encourage adapting models to diverse user preferences. However, most prior work on personalized reward models heavily rely on additional identity information, such as demographic details or a predefined set of preference categories. To this end, we introduce SynthesizeMe, an approach to inducing synthetic user personas from user interactions for personalized reward modeling. SynthesizeMe first generates and verifies reasoning to explain user preferences, then induces synthetic user personas from that reasoning, and finally filters to informative prior user interactions in order to build personalized prompts for a particular user. We show that using SynthesizeMe induced prompts improves personalized LLM-as-a-judge accuracy by 4.4% on Chatbot Arena. Combining SynthesizeMe derived prompts with a reward model achieves top performance on PersonalRewardBench: a new curation of user-stratified interactions with chatbots collected from 854 users of Chatbot Arena and PRISM.

Across many taxa, males gather in leks to perform multisensory courtship displays for females. At a lek, changes in the sensory scene over the course of mate evaluation are inevitable. This dynamic nature makes a female’s ability to recall the location of individual signalers an important component of female mate choice. It is hypothesized that complex (especially multimodal) displays may improve a female’s ability to remember and thus discriminate amongst potential mates. To test this hypothesis, we presented female túngara frogs ( Physalaemus (= Engystomops ) pustulosus ) with male calls (auditory) and robotic frogs (visual) that could later be obstructed from view via the lowering of blinds. Specifically, we asked if the visual component of a multimodal display improves the ability of a receiver to remember a signaler. While our initial experiment did not find memory instantiation in female frogs, subsequent experiments with a longer presentation time and a brief period of silence successfully instantiated memories in females. Moreover, females continued to demonstrate significant preferences for calls associated with the visual cue even after 25 s following the obstruction of the visual stimulus (robotic frog). Thus, we propose that the duration of presentation and/or the silent period impact memory capability. Silence is common in choruses, and our data suggest that complex, multisensory stimuli may have evolved to help females remember their preferred mate even with such fluctuations in signal production. LAY SUMMARY Multisensory signals function to stimulate one or more of a receiver’s senses, and in doing so, may make signalers more memorable to receivers. Multisensory signals are common in mating displays, including the advertisement of a male túngara frog: a call (acoustic) and a vocal sac inflation (visual). Here, we demonstrate that female túngara frogs were more likely to remember a multisensory male display over a unisensory display, but only after fluctuations in the signal’s intensity. ### Competing Interest Statement The authors have declared no competing interest. National Science Foundation, https://ror.org/021nxhr62, IOS-1914646

For chorusing males, optimally timing their calls relative to nearby rivals' calls and fluctuations in background chorus noise is crucial for reproductive success. A caller's acoustic environment will vary by chorus density and the properties of his chorus-mates' calls and will fluctuate unpredictably due to chorusing dynamics emerging among his chorus-mates. Thus, callers must continuously monitor moment-to-moment fluctuations in the acoustic scene they perceive at the chorus for advantageous times to call. In live experimental choruses, we investigated the factors influencing t & uacute;ngara frog call-timing responses to chorus-mates' calls on an interaction-by-interaction basis, revealing that intrinsic and extrinsic factors influenced call-timing decisions. Callers were more likely to overlap calls from smaller chorus-mates and chorus-mates at intermediate distances, as well as calls containing lower frequencies and exhibiting lower final amplitude minima. Consequently, variation among males in call properties led to variation in levels of call-interference received when calling in the same social environment. Additionally, callers were more likely to overlap chorus-mates' calls after experiencing extended periods of inhibition and were less likely to overlap synchronized chorus-mates' calls relative to single calls. In chorusing species, female choice is influenced by inter-caller dynamics, selecting for male call-timing strategies which, in turn, constitute the selective environment further refining these same strategies. Thus, understanding the specific factors driving call-timing decisions is essential for understanding how sexual selection operates in chorusing taxa. Chorusing t & uacute;ngara frogs track changes in background chorus noise levels to allow them to place calls in unpredictably occurring quiet gaps. When doing so, they are sensitive to chorus noise fluctuations produced by several lower-level processes, such as variation in the properties of the calls of nearby rivals, the relative spatial arrangement of these rivals, and the kinds of calling interactions occurring among them.

Acoustic communication signals are important for species recognition and mate attraction across numerous taxa. For instance, most of the thousands of species of frogs have a species-specific advertisement call that females use to localize and discriminate among potential mates. Thus, the acoustic structure of the advertisement call is critical for reproductive success. The acoustic structure of calls will generally diverge over evolutionary time and can be influenced by the calls of sympatric species. While many studies have shown the influence of geography on contemporary call variation in populations of frogs, no study has compared the acoustic structure of frog calls across many species to ask whether we can detect an influence of divergence time and overall geographic overlap on the differences in acoustic structure of species-typical calls that we observe now. To this end, we compared acoustic features of the calls of 225 species of frogs within 4 families. Furthermore, we used a behavioral assay from 1 species of frog to determine which acoustic features to prioritize in our large-scale analyses. We found evidence that both phylogeny (time) and geography (place) relate to advertisement call acoustics albeit with large variation in these relationships across the 4 families in the analysis. Overall, these results suggest that, despite the many ecological and evolutionary forces that influence call structure, the broad forces of time and place can shape aspects of advertisement call acoustics.

Sexual selection can result in the evolution of extreme armaments and ornaments, and the development and maintenance of these traits can come at a considerable cost. These costs have been implicated in enforcing an upper limit on trait divergence and promoting condition-dependent traits such that only individuals in sufficiently high condition can effectively wield these armaments and advertise these ornaments. Numerous studies demonstrate the condition-dependence of sexually selected traits, especially those used by males to advertise to females. In this study, we investigated condition-dependent mating calls in the túngara frog Physalaemus (=Engystomops) pustulosus. We manipulated male condition in the laboratory over a nine-day period by restricting food availability. We then documented the relationship between male condition (the relative change in body mass from night 1 to night 9) and acoustic parameters of his mating call; how male condition influenced the male’s responses to call playbacks; and finally, if male condition influenced the attractiveness of the male’s calls to females. Males who were not fed during this period showed significant changes in call frequency, duration, and amplitude. In response to playbacks, unfed males called less, and made fewer complex calls. Finally, in phonotaxis experiments, females were more attracted to the calls of unfed males on night 1 to the calls of the same males on night 9. Fed males, on the other hand, showed no significant differences between nights 1 and 9 in call parameters, calling effort, and call attractiveness. This study shows the pervasive effects of condition on three aspects of sexual communication: signal parameters, behavioral response to vocal competition, and mating call attractiveness.

Extreme climatic events, such as hurricanes, droughts, and floods, have been implicated in altering various phenotypic traits in affected populations. The 2015 El Niño cycle led to one of the driest wet seasons recorded throughout parts of Central America. We examined the effects of this climatic event on sexual and natural selection using behavioral and morphological data from túngara frogs (Engystomops pustulosus) collected before, during, and after this event. In a species renowned for robust female mating preferences, we found a cross-generational reduction and loss of female mate preferences for certain male advertisement call properties following this event. We identified reductions in body length and simultaneous increases in condition during the climatic event. Reduced availability and permanence of aquatic breeding sites may explain these behavioral and morphological changes. Mate choice preferences reverted rapidly, while the restoration of body length was sex dependent following this period of drastically reduced precipitation. These findings highlight immediate and lingering effects of single climatic events and demonstrate the ability of climatic events to disrupt established mate preferences. As climate change increases the frequency and severity of extreme events, monitoring behavioral and morphological phenotypes will be imperative to fully understand the consequences of these events on animal populations.