Richard W. Byrne

Machiavellian intelligence : social expertise and the evolution of intellect in monkeys, apes, and humans

Editorial - the Machiavellian intelligence hypotheses. The origins of the idea what primates know about social relationships social complexity - the effect of a third party are primates mind-readers? deception - including tactical deception in baboons, deception and social manipulation in symbol-using apes, the ontogeny of tactical deception in humans social or non-social origins of intelligence? exploiting the expertise of others taking stock - including the experimental context of intellect, the evolution of purpose. References. Index.

Tactical deception in primates

Tactical deception occurs when an individual is able to use an “honest” act from his normal repertoire in a different context to mislead familiar individuals. Although primates have a reputation for social skill, most primate groups are so intimate that any deception is likely to be subtle and infrequent. Published records are sparse and often anecdotal. We have solicited new records from many primatologists and searched for repeating patterns. This has revealed several different forms of deceptive tactic, which we classify in terms of the function they perform. For each class, we sketch the features of another individuals state of mind that an individual acting with deceptive intent must be able to represent, thus acting as a “natural psychologist.” Our analysis will sharpen attention to apparent taxonomic differences. Before these findings can be generalized, however, behavioral scientists must agree on some fundamental methodological and theoretical questions in the study of the evolution of social cognition.

The thinking ape : evolutionary origins of intelligence

Introduction: the limits of fossil evidence 1. Taxonomy and the reconstruction of evolution 2. What is intelligence and what is it for? 3. How animals learn 4. Why animals learn better in social groups 5. Imitative behaviour in animals 6. Understanding how things work 7. Understanding minds: doing and seeing, knowing and thinking 8. What use is a theory of mind? 9. Planning and thinking ahead 10. Apes and language 11. Food for thought 12. Machiavellian intelligence 13. Testing the theories 14. Taking stock

Memory for urban geography

Consistent patterns of errors are found in estimations of distances and angles along urban routes, even among subjects who know the areas well. These patterns can be used to discover the organization of the knowledge we use to find our way around in everyday life. In the first experiment, 80 undergraduates estimated by ratio scaling the walking distances between pairs of locations in St. Andrews. Routes varied independently in their location, number of major bends, and length. Relative overestimation of length was found with routes in the town centre, with routes having several major bends, and (perhaps as an experimental artifact) with short routes. In the second experiment, 30 Cambridge residents estimated the angles between pairs of roads, by drawing the configuration of roads at their junctions. The real angles were either in the range 60–70° or 110–120°. All the estimates differed little from 90°, regardless of the true magnitude of the angle. The implications of these findings for theories of mental representation of largescale space are discussed. A model is supported in which a spatial area is represented as a “network-map”, consisting of strings of locations forming a net of paths known to be traversable, but vector distance is not preserved.

Neocortex size predicts deception rate in primates.

Human brain organization is built upon a more ancient adaptation, the large brain of simian primates: on average, monkeys and apes have brains twice as large as expected for mammals of their size, principally as a result of neocortical enlargement. Testing the adaptive benefit of this evolutionary specialization depends on finding an association between brain size and function in primates. However, most cognitive capacities have been assessed in only a restricted range of species under laboratory conditions. Deception of conspecifics in social circumstances is an exception, because a corpus of field data is available that encompasses all major lines of the primate radiation. We show that the use of deception within the primates is well predicted by the neocortical volume, when observer effort is controlled for; by contrast, neither the size of the rest of the brain nor the group size exert significant effects. These findings are consistent with the hypothesis that neocortical expansion has been driven by social challenges among the primates. Complex social manipulations such as deception are thought to be based upon rapid learning and extensive social knowledge; thus, learning in social contexts may be constrained by neocortical size.

Ecology, feeding competition and social structure in baboons

Abstract Predictions of the model of van Schaik (1989) of female-bonding in primates are tested by systematically comparing the ecology, level of within-group contest competition for food (WGC), and patterns of social behaviour found in two contrasting baboon populations. Significant differences were found in food distribution (percentage of the diet from clumped sources), feeding supplant rates and grooming patterns. In accord with the model, the tendencies of females to affiliate and form coalitions with one another, and to be philopatric, were strongest where ecological conditions promoted WGC. Group fission in the population with strong WGC was “horizontal” with respect to female dominance rank, and associated with female-female aggression during a period of elevated feeding competition. In contrast, where WGC was low, females’ grooming was focused on adult males rather than other females. Recent evidence suggests that group fission here is initiated by males, tends to result in the formation of one-male groups, and is not related to feeding competition but to male-male competition for mates. An ecological model of baboon social structure is presented which incorporates the effects of female-female competition, male-male competition, and predation pressure. The model potentially accounts for wide variability in group size, group structure and social relationships within the genus Papio. Socio-ecological convergence between common baboons and hamadryas baboons, however, may be limited in some respects by phylogenetic inertia.

A lifetime psychiatric history predicts a worse seizure outcome following temporal lobectomy

Purpose: To identify the psychiatric and epilepsy variables predictive of postsurgical seizure outcome after anterotemporal lobectomy (ATL). Methods: Retrospective study of 100 consecutive patients with temporal lobe epilepsy (TLE) who underwent ATL. The mean (± SD) follow-up period was 8.3 (± 3.1) years. Three types of surgical outcomes were examined at 2 years after surgery and at last contact: class IA (no disabling seizures no auras), class IA + IB (no disabling seizures), and class IA + IB + IC (no or rare disabling seizures in the first postsurgical year). Logistic regression analyses were performed separately for the three types of surgical outcomes. The epilepsy-related independent variables included age at onset, cause of TLE (mesial temporal sclerosis, lesional and cryptogenic TLE), extent of resection of mesial structures, neuropathologic abnormalities, having only complex partial seizures, and duration of the seizure disorder. The psychiatric independent variables included a postsurgical and presurgical lifetime history of mood, anxiety, attention deficit hyperactivity, and psychotic disorders. Results: The absence of a psychiatric history was an independent predictor of all three types of surgical outcomes. In addition, a larger resection of mesial structures was a predictor for class IA outcome, and having only complex partial seizures (vs generalized tonic–clonic seizures) was a predictor for class IA + IB and IA + IB + IC. Having mesial temporal sclerosis (vs other causes of TLE) was a predictor for class IA + IB + IC as well. Conclusions: These data indicate that a lifetime psychiatric history may be predictive of a worse postsurgical seizure outcome after an anterotemporal lobectomy.

Gestural communication of the gorilla (Gorilla gorilla): repertoire, intentionality and possible origins

Social groups of gorillas were observed in three captive facilities and one African field site. Cases of potential gesture use, totalling 9,540, were filtered by strict criteria for intentionality, giving a corpus of 5,250 instances of intentional gesture use. This indicated a repertoire of 102 gesture types. Most repertoire differences between individuals and sites were explicable as a consequence of environmental affordances and sampling effects: overall gesture frequency was a good predictor of universality of occurrence. Only one gesture was idiosyncratic to a single individual, and was given only to humans. Indications of cultural learning were few, though not absent. Six gestures appeared to be traditions within single social groups, but overall concordance in repertoires was almost as high between as within social groups. No support was found for the ontogenetic ritualization hypothesis as the chief means of acquisition of gestures. Many gestures whose form ruled out such an origin, i.e. gestures derived from species-typical displays, were used as intentionally and almost as flexibly as gestures whose form was consistent with learning by ritualization. When using both classes of gesture, gorillas paid specific attention to the attentional state of their audience. Thus, it would be unwarranted to divide ape gestural repertoires into ‘innate, species-typical, inflexible reactions’ and ‘individually learned, intentional, flexible communication’. We conclude that gorilla gestural communication is based on a species-typical repertoire, like those of most other mammalian species but very much larger. Gorilla gestures are not, however, inflexible signals but are employed for intentional communication to specific individuals.

Poor drug distribution as a possible explanation for the results of the PRECISE trial

OBJECT Convection-enhanced delivery (CED) is a novel intracerebral drug delivery technique with considerable promise for delivering therapeutic agents throughout the CNS. Despite this promise, Phase III clinical trials employing CED have failed to meet clinical end points. Although this may be due to inactive agents or a failure to rigorously validate drug targets, the authors have previously demonstrated that catheter positioning plays a major role in drug distribution using this technique. The purpose of the present work was to retrospectively analyze the expected drug distribution based on catheter positioning data available from the CED arm of the PRECISE trial. METHODS Data on catheter positioning from all patients randomized to the CED arm of the PRECISE trial were available for analyses. BrainLAB iPlan Flow software was used to estimate the expected drug distribution. RESULTS Only 49.8% of catheters met all positioning criteria. Still, catheter positioning score (hazard ratio 0.93, p = 0.043) and the number of optimally positioned catheters (hazard ratio 0.72, p = 0.038) had a significant effect on progression-free survival. Estimated coverage of relevant target volumes was low, however, with only 20.1% of the 2-cm penumbra surrounding the resection cavity covered on average. Although tumor location and resection cavity volume had no effect on coverage volume, estimations of drug delivery to relevant target volumes did correlate well with catheter score (p < 0.003), and optimally positioned catheters had larger coverage volumes (p < 0.002). Only overall survival (p = 0.006) was higher for investigators considered experienced after adjusting for patient age and Karnofsky Performance Scale score. CONCLUSIONS The potential efficacy of drugs delivered by CED may be severely constrained by ineffective delivery in many patients. Routine use of software algorithms and alternative catheter designs and infusion parameters may improve the efficacy of drugs delivered by CED.

Habitat use and resource availability in baboons

The behavioural responses of free-living baboons (Papio) to temporal and spatial variation in resources is examined. Group foraging effort was related to per caput food availability, both within the study group (P. anubis) and across a sample of populations. Group size was positively correlated with both home range size and day range length, indicating ecological costs not predicted by a food defence hypothesis of group living. Furthermore, the tendency for day range length of the study group to increase as resources became scarcer was mirrored by inter-population variation; day range length was correlated negatively with mean annual rainfall, once the positive influence of group size had been partialled out. These relationships, which imply a time minimizing rather than an energy maximizing strategy, may be best explained by increased patchiness of food at lower resource densites, rather than lower average biomass within patches. The study group responded to the inferred decrease in the marginal value of patches in the dry season by increasing patch residency times. Multiple regression analysis of total time spent in each quadrat revealed that apparent preferences for particular vegetation zones were a result of the spatial coincidence of these zones with sleeping sites and waterholes, emphasizing the importance of controlling for confounding factors in studying the determinants of habitat selection. In addition, the mean duration of bouts in each quadrat was related to distance to the nearest waterhole, reflecting the constraints imposed by thermoregulatory water loss in a hot, dry environment. Seasonal shifts in habitat selection tracked spatio-temporal variation in the availability of food and water.