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Pichardo, M. (2000). Valsequillo biostratigraphy. III: Equid ecospecies in Paleoindian sites. Anthropol Anz, 58(3), 275–298.
Abstract: Greater precision in North American Pleistocene equid taxonomy makes it now possible to exploit the ubiquitous horse remains in Paleoindian sites as ecological index-fossils. The horses of Central Mexico and the Southern Plains can be sorted by tooth size alone, except for two rare large horses of the Southern Plains. The species endemic to these grasslands and south to Central Mexico are Equus pacificus (large), E. conversidens (small), E. francisci (smallest). The Southern Plains were also occupied by a specialized grazer E. excelsus (Burnet and Sandia caves) and E. occidentalis (Dry and Sandia caves). West of the Rocky Mountains E. occidentalis was dominant. East of the Mississippi River two woodland species are found: E. fraternus and E. littoralis.
Keywords: Animals; *Ecology; Horses/*classification; Mexico; *Paleodontology; Species Specificity
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Parish, A. R., & De Waal, F. B. (2000). The other “closest living relative”. How bonobos (Pan paniscus) challenge traditional assumptions about females, dominance, intra- and intersexual interactions, and hominid evolution. Ann N Y Acad Sci, 907, 97–113.
Abstract: Chimpanzee (Pan troglodytes) societies are typically characterized as physically aggressive, male-bonded and male-dominated. Their close relatives, the bonobos (Pan paniscus), differ in startling and significant ways. For instance, female bonobos bond with one another, form coalitions, and dominate males. A pattern of reluctance to consider, let alone acknowledge, female dominance in bonobos exists, however. Because both species are equally “man's” closest relative, the bonobo social system complicates models of human evolution that have historically been based upon referents that are male and chimpanzee-like. The bonobo evidence suggests that models of human evolution must be reformulated such that they also accommodate: real and meaningful female bonds; the possibility of systematic female dominance over males; female mating strategies which encompass extra-group paternities; hunting and meat distribution by females; the importance of the sharing of plant foods; affinitive inter-community interactions; males that do not stalk and attack and are not territorial; and flexible social relationships in which philopatry does not necessarily predict bonding pattern.
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Jezierski T., G. A. (2000). Changes in the horses heart rate during different levels of social isolation. Anim. Sci. Pap. Rep., 18(1), 33–41.
Abstract: Social isolation in horses may be regarded as a stress factor which implies welfare problems. The aim of the experiment was to examine the effect of different levels of transient social isolation and human presence on the heart rate (HR) in horses. Seven horses were used and the experiment was conducted in a tether-stable without boxes. The HR was recorded electronically, continuously for 40 min during the following test situations: all horses in the stable; experimenter approaches the tested horse, other horses being untied and leaving the stable; tested horse staying alone or in the company of one or two stable-mates; the experimenter attempts to calm the isolated horse; outdoor auditory stimuli from other horses. The HR was significantly higher during the whole period of isolation, and depended on how many horses were left as company for the one tested. The highest HR was observed while other horses were leaving the stable and during perception of outdoor auditory stimuli from others. When in the company of two stable mates, the HR was elevated only while other horses were leaving the stable and during auditory stimuli from outdoors. Human presence evoked a significant increase in HR, probably due to conditioning of horses (expecting to be untied and allowed to join the others), irrespectively whether the tested horse was left alone or with one or two stable-mates.
Keywords: horse; heart rate; human-animal relation
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B. Agnetta,, B. Hare,, & M. Tomasello,. (2000). Cues to food location that domestic dogs (Canis familiaris) of different ages do and do not use. Anim. Cogn., 3(2), 107–112.
Abstract: Autoren
B. Agnetta, B. Hare, M. Tomasello Zusammenfassung The results of three experiments are reported. In the main study, a human experimenter presented domestic dogs (Canis familiaris) with a variety of social cues intended to indicate the location of hidden food. The novel findings of this study were: (1) dogs were able to use successfully several totally novel cues in which they watched a human place a marker in front of the target location; (2) dogs were unable to use the marker by itself with no behavioral cues (suggesting that some form of human behavior directed to the target location was a necessary part of the cue); and (3) there were no significant developments in dogs' skills in these tasks across the age range 4 months to 4 years (arguing against the necessity of extensive learning experiences with humans). In a follow-up study, dogs did not follow human gaze into “empty space” outside of the simulated foraging context. Finally, in a small pilot study, two arctic wolves (Canis lupus) were unable to use human cues to locate hidden food. These results suggest the possibility that domestic dogs have evolved an adaptive specialization for using human-produced directional cues in a goal-directed (especially foraging) context. Exactly how they understand these cues is still an open question. Schlüsselwörter Key words Dogs – Arctic wolves – Social cognition – Gaze following – Communication |
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Potì, P. (2000). Aspects of spatial cognition in capuchins (Cebus apella): frames of reference and scale of space. Anim. Cogn., 3(2), 69–77.
Abstract: Frames of reference (i.e. sets of loci defining spatial locations) determine animals' performances in object search tasks. Reference frames are used at different scales. Although much behavioural research has been conducted on search strategies in many animal species, relatively little has been done on nonhuman primates. The two experiments reported here focused on the relative strength and the level of functioning of different reference frames at the small-scale level in four capuchins (Cebus apella). Two identical boxes and a landmark were placed on a round platform that could be rotated. A reward was hidden in subject's view under one box, and then a sash-screen was lowered to hide the rotation of the platform; the sash-screen was then lifted and the subject allowed to search for the reward. In experiment 1 the rewarded box was always the closer to the landmark, in experiment 2 it could be either the box closer to or the box farther from the landmark. Capuchins were successful after invisible rotations in experiment 1, but they failed after invisible rotations in experiment 2. Two possible explanations are proposed: (1) capuchins relied heavily on the left-right body-axis as a frame, and they could only substitute it with a simple association between the rewarded position and the landmark; or (2) capuchins failed because they chose external cues in the room, therefore on a inappropriate scale. The latter explanation allows two further inferences: (a) the capuchins' choice was indirectly related to their body-axes; and (b) the capuchins revealed a cognitive asymmetry between small-scale and large-scale spaces, thus differing from humans.
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Forkman, B. (2000). Domestic hens have declarative representations. Anim. Cogn., 3(3), 135–137.
Abstract: It is generally considered that information can be stored either as a procedural or as a declarative representation. A devaluation technique was used to determine whether hens have declarative representations. Individual hens (Gallus gallus domesticus) were fed in an enclosure with two containers, each with a new food type. One of the food types was devalued by pre-feeding with that food, after which the hens were tested with empty food containers. The pre-feeding should only affect the choice of the hens if they have learned where a particular food type was (declarative representation) rather than “go left when coming into the enclosure” (procedural representation). A significant proportion of the hens went to the location previously occupied by the non-devalued food (seven out of eight). This supports the hypothesis that domestic hens can form declarative representations.
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Xia, L., Siemann, M., & Delius, J. D. (2000). Matching of numerical symbols with number of responses by pigeons. Anim. Cogn., 3(1), 35–43.
Abstract: Pigeons were trained to peck a certain number of times on a key that displayed one of several possible numerical symbols. The particular symbol displayed indicated the number of times that the key had to be pecked. The pigeons signalled the completion of the requirement by operating a separate key. They received a food reward for correct response sequences and time-out penalties for incorrect response sequences. In the first experiment nine pigeons learned to allocate 1, 2, 3 or 4 pecks to the corresponding numerosity symbols s1, s2, s3 and s4 with levels of accuracy well above chance. The second experiment explored the maximum set of numerosities that the pigeons were capable of handling concurrently. Six of the pigeons coped with an s1-s5 task and four pigeons even managed an s1-s6 task with performances that were significantly above chance. Analysis of response times suggested that the pigeons were mainly relying on a number-based rather than on a time-based strategy.
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Call, J., Agnetta, B., & Tomasello, M. (2000). Cues that chimpanzees do and do not use to find hidden objects. Anim. Cogn., 3(1), 23–34.
Abstract: Chimpanzees follow conspecific and human gaze direction reliably in some situations, but very few chimpanzees reliably use gaze direction or other communicative signals to locate hidden food in the object-choice task. Three studies aimed at exploring factors that affect chimpanzee performance in this task are reported. In the first study, vocalizations and other noises facilitated the performance of some chimpanzees (only a minority). In the second study, various behavioral cues were given in which a human experimenter either touched, approached, or actually lifted and looked under the container where the food was hidden. Each of these cues led to enhanced performance for only a very few individuals. In the third study – a replication with some methodological improvements of a previous experiment – chimpanzees were confronted with two experimenters giving conflicting cues about the location of the hidden food, with one of them (the knower) having witnessed the hiding process and the other (the guesser) not. In the crucial test in which a third experimenter did the hiding, no chimpanzee found the food at above chance levels. Overall, in all three studies, by far the best performers were two individuals who had been raised in infancy by humans. It thus seems that while chimpanzees are very good at “behavior reading” of various sorts, including gaze following, they do not understand the communicative intentions (informative intentions) behind the looking and gesturing of others – with the possible exception of enculturated chimpanzees, who still do not understand the differential significance of looking and gesturing done by people who have different knowledge about states of affairs in the world.
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Durier, V., & Rivault, C. (2000). Learning and foraging efficiency in German cockroaches, Blattella germanica (L.) (Insecta: Dictyoptera). Anim. Cogn., 3(3), 139–145.
Abstract: We analysed, under laboratory test conditions, how German cockroach larvae oriented their outgoing foraging trip from their shelter. Our results stressed the importance of external factors, like availability and spatial distribution of food sources, in the choice of a foraging strategy within their home range. When food sources were randomly distributed, larvae adopted a random food search strategy. When food distribution was spatially predictable and reliable, cockroaches were able to relate the presence of food with a landmark during a 3-day training period and to develop an oriented search strategy. Cockroaches were able to associate learned spatial information about their home range to the presence of food resources and then to improve their foraging efficiency. However, conflict experiments revealed that detection of food odour overrode learned landmark cues.
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Depraz, V., Leboucher, G., & Kreutzer, M. (2000). Early tutoring and adult reproductive behaviour in female domestic canary (Serinus canaria). Anim. Cogn., 3(1), 45–51.
Abstract: We studied the effect of early tutoring on the subsequent sexual preferences and reproductive activity of female domestic canaries (Serinus canaria). Young female canaries were exposed during the first 4 months of life to songs of either domestic or wild canaries. When adult, these females were again exposed to domestic or wild songs. In the first experiment, the sexual responses of the females to unfamiliar domestic and wild songs were quantified with the copulation solicitation display (CSD) assay. In the second experiment, the same females were tested again with modified tutoring songs. In the third experiment, song stimulation of nest-building and egg-laying was studied. Domestic-strain-tutored females gave more CSDs to domestic than to wild songs. In contrast, wild-strain-tutored females showed no sexual preference. We propose that the sexual preference of adult domestic-strain-tutored female canaries for domestic songs is the consequence of learning and categorisation processes. The discrepancy between the results of the domestic-strain-tutored females and those of the wild-strain-tutored females suggests that female canaries have a predisposition to learn songs of their own strain rather than songs of an alien strain. In the third experiment nest-building and egg-laying activities appeared to be unaffected by early tutoring conditions: there was no significant differential effect of the different tutoring and exposure conditions on nest-building and egg-laying scores. Mate attraction and stimulation of females' reproductive activity appear to be two separate functions of male song, which may have been shaped by different evolutionary constraints.
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