Understanding the information conveyed by animal signals requires studies of both production and perception. It is important to determine the relationship between signal morphology and the circumstances of production, the way signaller behavior varies with motivational state and the role of context in mediating responses to signals. Alarm calls are well-suited to research of this type because they are widespread in birds and mammals and typically evoke unambiguous responses. We review studies of alarm calling in primates and ground-dwelling sciurid rodents, concentrating especially on whether these signal systems may be viewed as ‘functionally referential’, that is, as conveying sufficient information about an event for receivers to select appropriate responses. Comparisons of the physical, behavioral and habitat characteristics of these species suggest that incompatibility of the escape responses required to avoid different classes of predators may have been an important factor in the evolution of functionally referential alarm calls.

Essay on Contemporary Issues in Ethology: Variation among Mammalian Alarm Call Systems and the Problem of Meaning in Animal Signals

Obesity represents one of the most serious global health issues with approximately 310 million people presently affected. It develops because of a mismatch between energy intake and expenditure that results from behavior (feeding behavior and time spent active) and physiology (resting metabolism and expenditure when active). Both of these traits are affected by environmental and genetic factors. The dramatic increase in the numbers of obese people in Western societies reflects mostly changing environmental factors and is linked to reduced activity and perhaps also increased food intake. However, in all societies and subpopulations, there are both obese and nonobese subjects. These differences are primarily a consequence of genetic factors as is revealed by the high heritability for body mass index. Most researchers agree that energy balance and, hence, body weight are regulated phenomena. There is some disagreement about exactly how this regulation occurs. However, a common model is the "lipostatic" regulation system, whereby our energy stores generate signals that are compared with targets encoded in the brain, and differences between these drive our food intake levels, activity patterns, and resting and active metabolisms. Considerable advances were made in the last decade in understanding the molecular basis of this lipostatic system. Some obese people have high body weight because they have broken lipostats, but these are a rare minority. This suggests that for the majority of obese people, the lipostat is set at an inappropriately high level. When combined with exposure to an environment where there is ready availability of food at low energy costs to obtain it, obesity develops. The evolutionary background to how such a system might have evolved involves the evolution of social behavior, the harnessing of fire, and the development of weapons that effectively freed humans from the risks of predation. The lipostatic model not only explains why some people become obese whereas others do not, but also allows us to understand why energy-controlled diets do not work. Drug-based solutions to the obesity problem that work with the lipostat, rather than against it, are presently under development and will probably be in regular use within 5-10 y. However, several lines of evidence including genetic mapping studies of quantitative trait loci associated with obesity suggest that our present understanding of the regulatory system is still rudimentary. In particular, we know nothing about how the target body weight in the brain is encoded. As our understanding in this field advances, new drug targets are likely to emerge and allow us to treat this crippling disorder.

Obesity: The Integrated Roles of Environment and Genetics

A molecular analysis based on the termination of stimuli that are positively correlated with shock and the production of stimuli that are negatively correlated with shock provides a parsimonious count for both traditional discrete-trial avoidance behavior and the data derived from more recent free-operant procedures. The necessary stimuli are provided by the intrinsic feedback generated by the subject's behavior, in addition to those presented by the experimenter. Moreover, all data compatible with the molar principle of shock-frequency reduction as reinforcement are also compatible with a delay-of-shock gradient, but some data compatible with the delay gradient are not compatible with frequency reduction. The delay gradient corresponds to functions relating magnitude of behavioral effect to the time between conditional and unconditional stimuli, the time between conditioned and primary reinforcers, and the time between responses and positive reinforcers.

https://sites.oxy.edu/clint/learn/articles/stimuliinevitablygeneratedbybehaviorthatavoidselectricshockareinherentlyreinforcing.pdf

Stimuli inevitably generated by behavior that avoids electric shock are inherently reinforcing.

Vocal communication in nonhuman primates receives considerable research attention, with many investigators arguing for similarities between this calling and speech in humans. Data from development and neural organization show a central role of affect in monkey and ape sounds, however, suggesting that their calls are homologous to spontaneous human emotional vocalizations while having little relation to spoken language. Based on this evidence, we propose two principles that can be useful in evaluating the many and disparate empirical findings that bear on the nature of vocal production in nonhuman and human primates. One principle distinguishes production-first from reception-first vocal development, referring to the markedly different role of auditory-motor experience in each case. The second highlights a phenomenon dubbed dual neural pathways, specifically that when a species with an existing vocal system evolves a new functionally distinct vocalization capability, it occurs through emergence of a second parallel neural pathway rather than through expansion of the extant circuitry. With these principles as a backdrop, we review evidence of acoustic modification of calling associated with background noise, conditioning effects, audience composition, and vocal convergence and divergence in nonhuman primates. Although each kind of evidence has been interpreted to show flexible cognitively mediated control over vocal production, we suggest that most are more consistent with affectively grounded mechanisms. The lone exception is production of simple, novel sounds in great apes, which is argued to reveal at least some degree of volitional vocal control. If also present in early hominins, the cortically based circuitry surmised to be associated with these rudimentary capabilities likely also provided the substrate for later emergence of the neural pathway allowing volitional production in modern humans.

Two organizing principles of vocal production: Implications for nonhuman and human primates

Summary This study examined the perceptual features of leopards (Panthera pardus) used as recognition cues by bonnet macaques (Macaca radiata) at three sites in southern India. Two of these sites were protected deciduous forest areas, the Mudumalai Wildlife Sanctuary and the Kalakad-Mundanthurai Tiger Reserve. The third study site was a predator-rare urban setting, Bangalore city. Four models were presentedfor 10-s intervals:(1) upright spotted leopard ina stalking proe le with its head facing the subjects;(2) the same spotted model presentedupside down; (3) a dark-brown leopard model with the same cone guration as the spotted model; and e nally (4), the dark-brown model presented upside down. The upright models characterized the two leopard morphs found in the wild — spotted and dark melanic. Inverted presentations of the spotted model examined the effects of the same cone guration in an incongruous position to document whether leopard spots were still recognized. Differences between models were examined using alarm calls and e ight elicitationas indices of fear. The spotted upright model was found to be the most feared, followed by the spotted upside-down model, the dark upright model, and e nally the dark upside-down model. Analysis of when individuals looked at troop members to assess risks revealed that the spotted upright and dark upsidedown models engendered signie cantly lower frequencies of information seeking; the upright model typically engendered immediate e ight and the dark upside-down model was generally ignored. The spotted upside-down model and the dark upright model engendered high rates

Perceptual aspects of leopard recognition by wild bonnet macaques (macaca radiata)

In Part 1, we analyzed alarm calls produced by captive vervets (Cercopithecus aethiops) in response to naturally occurring stimuli. Females and juveniles regularly alarm called to airplanes, birds, and barking dogs. Juvenile females accounted for 60% of these alarm calls. In Part 2, we isolated several monkeys from the colony and presented them with life-sized silhouettes of a leopard, snake, eagle, baboon, vervet, and goose. Adult monkeys alarm called more than did juveniles. Alarm calls were elicited by leopard, snake, baboon, and vervet silhouettes, but none were elicited by eagle or goose silhouettes. Some leopard and snake alarm calls matched those recorded in the wild in the context of the vervets' natural predators. Results indicate that silhouette stimuli are a useful technique for eliciting monkey vocalizations in the laboratory.

Silhouettes elicit alarm calls from captive vervet monkeys (Cercopithecus aethiops).

If the functional relations governing the strength of a conditioned reinforcer correspond to those obtained with other Pavlovian procedures (e.g., Kaplan, 1984), the termination of stimuli appearing early in the interval between successive food deliveries should be reinforcing. During initial training we presented four key colors, followed by food, in a recurrent sequence to each of 6 pigeons. This established a baseline level of autoshaped pecking. In later sessions, we terminated each of these colors or only the first color for a brief period following each peck, replacing the original color with a standard substitute to avoid darkening the key. Pecking decreased in the presence of the last color in the sequence but increased in the presence of the first. In accord with contemporary models of Pavlovian conditioning, these and other data suggest that the behavioral effects of stimuli in a chain may be better understood in terms of what each stimulus predicts, as measured by relative time to the terminal reinforcer, than in the exclusively positive terms of the traditional formulation (Skinner, 1938). The same model may also account for the initial pause under fixed-interval and fixed-ratio schedules of reinforcement.

/pdf/escape-from-serial-stimuli-leading-to-food-5ditrm6a0i.pdf

Marceline M. Brown

Papers

Silhouettes elicit alarm calls from captive vervet monkeys (Cercopithecus aethiops).

Escape from serial stimuli leading to food.