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Griffin, D. R. (1998). From cognition to consciousness. Anim. Cogn., 1(1), 3–16.
Abstract: This paper proposes an extension of scientific horizons in the study of animal behavior and cognition to include conscious experiences. From this perspective animals are best appreciated as actors rather than passive objects. A major adaptive function of their central nervous systems may be simple, but conscious and rational, thinking about alternative actions and choosing those the animal believes will get what it wants, or avoid what it dislikes or fears. Versatile adjustment of behavior in response to unpredictable challenges provides strongly suggestive evidence of simple but conscious thinking. And especially significant objective data about animal thoughts and feelings are already available, once communicative signals are recognized as evidence of the subjective experiences they often convey to others. The scientific investigation of human consciousness has undergone a renaissance in the 1990s, as exemplified by numerous symposia, books and two new journals. The neural correlates of cognition appear to be basically similar in all central nervous systems. Therefore other species equipped with very similar neurons, synapses, and glia may well be conscious. Simple perceptual and rational conscious thinking may be at least as important for small animals as for those with large enough brains to store extensive libraries of behavioral rules. Perhaps only in “megabrains” is most of the information processing unconscious.
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Czeschlik, T. (1998). Animal cognition – the phylogeny and ontogeny of cognitive abilities. Anim. Cogn., 1(1), 1–2.
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Wanker, R., Apcin, J., Jennerjahn, B., & Waibel, B. (1998). Discrimination of different social companions in spectacled parrotlets ( Forpus conspicillatus ): evidence for individual vocal recognition. Behav. Ecol. Sociobiol., 43(3), 197–202.
Abstract: Abstract: Individual recognition is generally assumed to be a prerequisite for establishing and maintaining a complex social system. Indeed, there is good evidence that highly social species have complex systems of vocal communication with individual recognition by acoustic cues. In this study, we provide experimental evidence that vocal class and individual recognition is present in a non-passerine bird, the spectacled parrotlet (Forpus conspicillatus). Spectacled parrotlets live in a complex system of social relationships. Soon after fledging, the young establish close sibling relationships which are important for successful socialization, pairing and reproduction. In a series of playback experiments we tested if spectacled parrotlets use contact calls for vocal recognition. The results showed that spectacled parrotlets discriminate between the contact calls of different social categories. Adult birds preferred to respond to the contact calls of their mates. Subadult individuals recognized the contact calls of their siblings. During the period of pair bond formation, the affiliative contacts to the siblings decrease, but the parrotlets continue to respond to the calls of their siblings. This is the first evidence that vocal sibling recognition might outlast the period of strong sibling interaction and extends into the period of pair bond formation. In cases of mate loss or divorce, the acoustic contact to their siblings might facilitate the re-establishment of close sibling relationships.
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Cameron, E. Z. (1998). Is suckling behaviour a useful predictor of milk intake? A review. Anim. Behav., 56(3), 521–532.
Abstract: In studies on mammalian parental investment, time spent suckling is often used as a predictor of the milk transferred from mother to infant. It is assumed that the rate of milk transfer is positively correlated with the time spent suckling. However, this assumption has not been tested and empirical studies show conflicting results. Nevertheless, in species in which suckling can readily be observed, time spent suckling is still used to measure milk transfer, although an increasing number of workers recognize that the measure is potentially inaccurate. A meta-analysis on studies that have correlated measures of time spent suckling with milk intake estimates based on weight gain revealed a weak positive relationship and significant heterogeneity between studies. Isotope-labelling techniques for the measurement of milk transfer independent of behaviour have been in use since the 1970s, particularly in studies of species in which suckling is difficult to observe. Only one study has attempted to correlate behavioural measures with independent isotope measures, and it found no relationship between the two measures. I suggest that researchers have avoided such a test as it is unlikely that a strong relationship will be found between milk transfer and suckling behaviour, and I discuss the various factors that confound the relationship and contribute to high heterogeneity between studies. Consequently, the assumption that milk transfer can be measured by time spent suckling has inadequate empirical foundation, and needs to be tested using isotope-labelling methods. Copyright 1998 The Association for the Study of Animal Behaviour
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Stoehr S. (1998). Evolution of mate-choice copying: a dynamic model. Anim. Behav., 55(4), 893–903.
Abstract: Mate-choice copying has recently been demonstrated in several species. Two, not mutually exclusive, explanations for copying have been proposed: it reduces sampling costs and/or error of mate choice. In guppies, Poecilia reticulata, and black grouse, Tetrao tetrix, young females seem most likely to copy. Therefore, copying may teach inexperienced females what attractive males look like. I developed a 2-year dynamic model, to investigate under which conditions a mate-copying strategy might first evolve. An original population of pure choosers was assumed, which was invaded by a mutant female, able to copy during her first mating season, thereby instantly improving her ability to assess male quality. Alternatively, she could either wait and learn by observing males, just as non-copiers may do, but incurring some time costs, or choose, relying on her own abilities. The degree to which copying occurred among these mutant, young, inexperienced females increased with an increasing proportion of old, experienced females in the population, and with decreasing time left until the end of the season. The model demonstrates that mate-choice copying may evolve, when young females are poor at discrimination and need to learn what high-quality males look like. Male quality proved to be unimportant for copying to evolve, as long as there are sufficient differences in quality for mate choice to be meaningful. As with previous models, time constraints are an important assumption for copying to be advantageous over non-copying. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.
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Potts, R. (1998). Variability selection in hominid evolution. Evol. Anthropol., 7(3), 81–96.
Abstract: Variability selection (abbreviated as VS) is a process considered to link adaptive change to large degrees of environment variability. Its application to hominid evolution is based, in part, on the pronounced rise in environmental remodeling that took place over the past several million years. The VS hypothesis differs from prior views of hominid evolution, which stress the consistent selective effects associated with specific habitats or directional trends (e.g., woodland, savanna expansion, cooling). According to the VS hypothesis, wide fluctuations over time created a growing disparity in adaptive conditions. Inconsistency in selection eventually caused habitat-specific adaptations to be replaced by structures and behaviors responsive to complex environmental change. Key hominid adaptations, in fact, emerged during times of heightened variability. Early bipedality, encephalized brains, and complex human sociality appear to signify a sequence of VS adaptations—i.e., a ratcheting up of versatility and responsiveness to novel environments experienced over the past 6 million years. The adaptive results of VS cannot be extrapolated from selection within a single environmental shift or relatively stable habitat. If some complex traits indeed require disparities in adaptive setting (and relative fitness) in order to evolve, the VS idea counters the prevailing view that adaptive change necessitates long-term, directional consistency in selection. © 1998 Wiley-Liss, Inc.
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Dunbar, R. I. M. (1998). The social brain hypothesis. Evol. Anthropol., 6(5), 178–190.
Abstract: Conventional wisdom over the past 160 years in the cognitive and neurosciences has assumed that brains evolved to process factual information about the world. Most attention has therefore been focused on such features as pattern recognition, color vision, and speech perception. By extension, it was assumed that brains evolved to deal with essentially ecological problem-solving tasks. © 1998 Wiley-Liss, Inc.
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Bergstrom, C. T., & Lachmann, M. (1998). Signaling among relatives. III. Talk is cheap. Proc. Natl. Acad. Sci. U.S.A., 95(9), 5100–5105.
Abstract: The Sir Philip Sidney game has been used by numerous authors to show how signal cost can facilitate honest signaling among relatives. Here, we demonstrate that, in this game, honest cost-free signals are possible as well, under very general conditions. Moreover, these cost-free signals are better for all participants than the previously explored alternatives. Recent empirical evidence suggests that begging is energetically inexpensive for nestling birds; this finding led some researchers to question the applicability of the costly signaling framework to nestling begging. Our results show that cost-free or inexpensive signals, as observed empirically, fall within the framework of signaling theory.
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Brannon, E. M., & Terrace, H. S. (1998). Ordering of the numerosities 1 to 9 by monkeys. Science, 282(5389), 746–749.
Abstract: A fundamental question in cognitive science is whether animals can represent numerosity (a property of a stimulus that is defined by the number of discriminable elements it contains) and use numerical representations computationally. Here, it was shown that rhesus monkeys represent the numerosity of visual stimuli and detect their ordinal disparity. Two monkeys were first trained to respond to exemplars of the numerosities 1 to 4 in an ascending numerical order (1 --> 2 --> 3 --> 4). As a control for non-numerical cues, exemplars were varied with respect to size, shape, and color. The monkeys were later tested, without reward, on their ability to order stimulus pairs composed of the novel numerosities 5 to 9. Both monkeys responded in an ascending order to the novel numerosities. These results show that rhesus monkeys represent the numerosities 1 to 9 on an ordinal scale.
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Schooening, B. (1998). Ethology of the horse. Prakt. Tierarzt, 79(6 Suppl.), 25–28.
Abstract: The paper starts with a short introduction/definition about ethology and the used methods in this scientific field, giving special examples for horses and about how their “normal behaviour” is measured. The behaviour repertoire of horses is described in a brief outline with special emphasis on their social systems and hierarchies and the problem of dominance, especially in interaction with humans. Schlütersche GmbH & Co. KG, Verlag und Druckerei.
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