Trying to uncover the roots of human speech and language has been the premier motivation to study the signalling behaviour of nonhuman primates for several decades. Focussing on the question of ...whether we find evidence for linguistic reference in the production of nonhuman primate vocalizations, I will first discuss how the criteria used to diagnose referential signalling have changed over time, and will then turn to the paradigmatic case of semantic communication in animals, the alarm calls of vervet monkeys,
Chlorocebus pygerythrus
. A recent in-depth analysis of the original material revealed that, while the alarm calls could be well distinguished, calls of similar structure were also used in within- and between-group aggression. This finding is difficult to reconcile with the idea that calls denote objects in the environment. Furthermore, nonhuman primates show only minimal signs of vocal production learning, one key prerequisite for conventionalized and symbolic communication. In addition, the structure of calls in different populations or closely related species is highly conserved. In conclusion, any continuity between nonhuman primate and human communication appears to be found at the level of the processing of signals. Why and how the ancestors of our own species one day began to talk to each other continues to be an enigma. Future research should focus on changes in the neural structure supporting volitional control over vocalizations, the gene networks associated with vocal production, and the developmental processes involved in the integration of production and perception of vocalizations.
Paired, single-atom catalysts have been shown to demonstrate synergistic effects computationally and experimentally which enable them to outperform the benchmark catalyst, Pt/C, for electrochemical ...reactions. We explore the limit of these catalysts by screening different transition metal atoms (M = Co, Pt, Fe, Ni) in nitrogen-doped graphene for their ability to catalyze the oxygen reduction reaction (ORR). We employ density functional theory methods to explore the electronic factors affecting catalytic activity in an effort to rationalize trends in the performance of materials which are promising candidates for the next generation of electrocatalysts. It is found that CoPt@N8V4, composed of paired Co and Pt in a nitrogen-doped four-atom vacancy in graphene (N8V4), performs ideally for the ORR with an overpotential (η) of 0.30 V, followed closely by Co and Ni (η = 0.35 V) and paired Co (η = 0.37 V). The origin of activity is suggested to be the changing reduction potential of the active Co atom via the local distortion of the pore by the spectating metal partner. We utilize the ORR scaling relations and plot catalytic activity on a volcano plot, which we correlate with the degree of antibonding interactions with the O atom in the OH intermediate of the ORR. We establish that the local tuning of paired catalysts allows for the reactivity of metal atoms to be specifically modified for desirable reactivity.
Towards a new taxonomy of primate vocal production learning Fischer, Julia; Hammerschmidt, Kurt
Philosophical transactions of the Royal Society of London. Series B. Biological sciences,
01/2020, Letnik:
375, Številka:
1789
Journal Article
Recenzirano
Odprti dostop
The extent to which vocal learning can be found in nonhuman primates is key to reconstructing the evolution of speech. Regarding the adjustment of vocal output in relation to auditory experience ...(vocal production learning in the narrow sense), effects on the ontogenetic trajectory of vocal development as well as adjustment to group-specific call features have been found. Yet, a comparison of the vocalizations of different primate genera revealed striking similarities in the structure of calls and repertoires in different species of the same genus, indicating that the structure of nonhuman primate vocalizations is highly conserved. Thus, modifications in relation to experience only appear to be possible within relatively tight species-specific constraints. By contrast, comprehension learning may be extremely rapid and open-ended. In conjunction, these findings corroborate the idea of an ancestral independence of vocal production and auditory comprehension learning. To overcome the futile debate about whether or not vocal production learning can be found in nonhuman primates, we suggest putting the focus on the different mechanisms that may mediate the adjustment of vocal output in response to experience; these mechanisms may include auditory facilitation and learning from success. This article is part of the theme issue 'What can animal communication teach us about human language?'
In the last decade, drones have become an affordable technology offering highly mobile aerial platforms that can carry a range of sensory equipment into hitherto uncharted areas. Drones have thus ...become a widely applicable tool for surveying animal populations and habitats to assist conservation efforts or to study the behavioural ecology of species by monitoring individual and group behaviour.
Here, we review current applications for drone surveys and the potential of recently developed computer algorithms for automatic species detection and individual tracking in drone footage. We further review which factors are reportedly associated with animal disturbance during drone presentations and how drones may be used to study anti‐predator behaviour.
Drone surveys of species and their environments allow scientists to create digital terrain models of habitats, estimate species abundance, monitor individual behaviour and study the composition, spatial organization and movement of groups. As drones can influence the behaviour of many bird and mammal species directly, they also provide an experimental tool to study animal responses to novel situations, including the drone itself.
We conclude that the combined use of drones and automated detection software can assist population estimates and opens new possibilities to study individual and collective behaviour. With regard to drone‐related disturbance and their potential use as predator models, we recommend to interpret results against the background of population‐specific predation pressure and sources of anthropogenic disturbance.
Metal heteroatoms dispersed in nitrogen-doped graphene display promising catalytic activity for fuel cell reactions such as the hydrogen evolution reaction (HER). Here we explore the effects of the ...dopant concentration on the synergistic catalytic behavior of a paired metal atom active site comprising Co and Pt atoms that have been shown to be particularly active catalysts in these materials. The metals are coordinated to six atoms in a vacancy of N-doped graphene. We find that the HER activity is enhanced with increasing N concentration, where the free energy of hydrogen atom adsorption ranges from 0.23 to −0.42 eV as the doping changes from a single N atom doped in the pore to fully doped coordination sites. The results indicate that the effect of N is to make the metal atoms more active toward H adsorption, presenting a means through which transition metals can be modified to make more effective and sustainable fuel cell catalysts.
The steepness of dominance hierarchies provides information about the degree of competition within animal social groups and is thus an important concept in socioecology. The currently most widely ...used metrics to quantify steepness are based on David's scores (DS) derived from dominance interaction networks. One serious drawback of these DS‐based metrics is that they are biased, that is, network density systematically decreases steepness values.
We provide a novel approach to estimate steepness based on Elo‐ratings, implemented in a Bayesian framework (STEER: Steepness estimation with Elo‐rating). We evaluate and validate its performance by means of experimentation on empirical and artificial datasets and compare its performance to that of several other steepness estimators.
STEER has two key advantages. First, it is unbiased, precise and more robust to data density than DS‐based steepness. Second, it provides explicit probability distributions of the estimated steepness coefficient, which allows uncertainty assessment. In addition, it relies on the same underlying concept and is on the same scale as the original measure, and thus allows comparison to existing published results.
STEER provides a considerable improvement over existing methods to estimate dominance hierarchy steepness. We demonstrate its application with an example comparing within‐ and between species variation in steepness in a comparative analysis and present guidelines on how to use it. The R package EloSteepness allows convenient numeric and graphical assessment of the new steepness measure.
Ritualized greetings, defined as exchanges of non-aggressive signals, are common among males living in multi-male groups and are thought to balance the trade-offs of male co-residence. While ...ritualized greetings are widespread in the animal kingdom, the behavioral repertoire described in the genus Papio is exceptional, as it involves potentially harmful behaviors such as genital fondling. Although greetings are one of the most striking male social interactions in baboons, their function is still disputed. We investigated the function of male–male ritualized greeting behavior in wild Guinea baboons. This species lives in multilevel societies where several ‘units’ comprising a primary male, females with young, and occasionally a secondary male form a ‘party’, and two to three parties form a gang. Adult males maintain affiliative relationships with preferred male partners whom they support in coalitions, regardless of kinship. We examined the social behavior of 24 adolescent and adult males (∼900 h focal observations) in the Niokolo-Koba National Park, Senegal, to test whether greetings reflect relationship quality or function to buffer tension. Greetings were ten times more frequent than aggression and twice as frequent as affiliation. Neither dyadic aggression nor tense context predicted greeting rate, discounting the buffering hypothesis. Greetings occurred almost exclusively between males of the same party, even when other parties were around. Within parties, spatially tolerant partners greeted more frequently but dyads did not greet due to proximity prior to the greeting. Although affiliation did not predict overall greeting rate, intense and potentially costly greetings were more likely between males with stronger affiliative relationships. Greetings in Guinea baboons appear to signal commitment among party members, test relationships among spatially tolerant partners, and accentuate relationship strength among highly affiliated males. Although ritualized baboon greetings lack the symbolic component of human rituals, they appear to serve similar functions, specifically to strengthen in-group affiliation and promote cooperation.
Against the background of the seminal papers on the vervet monkey alarm call system by Seyfarth, Cheney and Marler (1980a. 1980b), I provide an overview of context specificity in calling and call ...comprehension learning in the genus Chlorocebus, and to which degree these findings inform the reconstruction of the evolution of speech and language. The alarm calls of vervet monkeys (Chlorocebus pygerythrus) and West African green monkeys (Chlorocebus sabaeus) are astoundingly similar in terms of the structure of calls given in response to their main predator types. Green monkeys also spontaneously produced calls that sounded like ‘eagle alarms’ in response to a novel aerial threat (a drone), supporting the view that both the link between the predator category and the call, as well as the call structure itself are largely hard-wired. In contrast, learning shapes the responses to sounds. As recent field experiments showed, monkeys are able to rapidly attach meaning to a novel sound, and they are also able to factor in contextual information when choosing their responses. These findings corroborate the view of a fundamental dichotomy in the degree of flexibility in terms of the production of calls with a specific structure vs. the comprehension of calls and suggest that the emergence of auditory learning abilities preceded the evolution of flexible vocal production. In summary, nonhuman primate communication shares fewer similarities with human speech than many scholars may have hoped for, but we would never have learned so much about primate vocal communication were it not for the breakthrough study by Seyfarth, Cheney, and Marler.
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