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Reddon, A. R., & Hurd, P. L. (2009). Individual differences in cerebral lateralization are associated with shy-bold variation in the convict cichlid. Anim. Behav., 77(1), 189–193.
Abstract: Cerebral lateralization, the preferential use of one hemisphere of the brain to perform certain cognitive functions, is a widespread and evolutionarily ancient adaptation. Lateralization appears to enhance cognitive capacity, yet substantial individual variation in the strength cerebral lateralization is apparent in all species studied so far. It is puzzling that cerebral lateralization, a seemingly advantageous trait, has not been driven to fixation. It has been suggested that variation in lateralization may be linked to individual variation in behaviour, which itself may be subject to disruptive selection. We examined the relation between cerebral lateralization and individual variation in boldness in the convict cichlid, Archocentrus nigrofasciatus. We show that convict cichlids that are more strongly lateralized when exploring a familiar environment, but not a novel one, are quicker to emerge from a shelter in a test for boldness. The possibility that cerebral lateralization is linked to life history strategy is discussed.
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Rowe, M. L., & Goldin-Meadow, S. (2009). Differences in Early Gesture Explain SES Disparities in Child Vocabulary Size at School Entry. Science, 323(5916), 951–953.
Abstract: Children from low-socioeconomic status (SES) families, on average, arrive at school with smaller vocabularies than children from high-SES families. In an effort to identify precursors to, and possible remedies for, this inequality, we videotaped 50 children from families with a range of different SES interacting with parents at 14 months and assessed their vocabulary skills at 54 months. We found that children from high-SES families frequently used gesture to communicate at 14 months, a relation that was explained by parent gesture use (with speech controlled). In turn, the fact that children from high-SES families have large vocabularies at 54 months was explained by children's gesture use at 14 months. Thus, differences in early gesture help to explain the disparities in vocabulary that children bring with them to school.
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Nguyen, N., Van Horn, R., Alberts, S., & Altmann, J. (2009). “Friendships” between new mothers and adult males: adaptive benefits and determinants in wild baboons (Papio cynocephalus). Behav. Ecol. Sociobiol., 63(9), 1331–1344.
Abstract: Close associations between adult males and lactating females and their dependent infants are not commonly described in non-monogamous mammals. However, such associations [sometimes called friendships (Smuts 1985)] are regularly observed in several primate species in which females mate with multiple males during the fertile period. The absence of mating exclusivity among friends suggests that males should invest little in infant care, raising questions about the adaptive significance of friendship bonds. Using data from genetic paternity analyses, patterns of behavior, and long-term demographic and reproductive records, we evaluated the extent to which friendships in four multi-male, multi-female yellow baboon (Papio cynocephalus) groups in Amboseli, Kenya represent joint parental care of offspring or male mating effort. We found evidence that mothers and infants benefited directly from friendships; friendships provided mother–infant dyads protection from harassment from other adult and immature females. In addition, nearly half of all male friends were the genetic fathers of offspring and had been observed mating with mothers during the days of most likely conception for those offspring. In contrast, nearly all friends who were not fathers were also not observed to consort with the mother during the days of most likely conception, suggesting that friendships between mothers and non-fathers did not result from paternity confusion. Finally, we found no evidence that prior friendship increased a male’s chances of mating with a female in future reproductive cycles. Our results suggest that, for many male–female pairs at Amboseli, friendships represented a form of biparental care of offspring. Males in the remaining friendship dyads may be trading protection of infants in exchange for some resources or services not yet identified. Our study is the first to find evidence that female primates gain social benefits from their early associations with adult males.
Keywords: Biomedical and Life Sciences
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Mitani, J. C. (2009). Male chimpanzees form enduring and equitable social bonds. Anim. Behav., 77(3), 633–640.
Abstract: Controversy exists regarding the nature of primate social relationships. While individual primates are frequently hypothesized to form enduring social bonds with conspecifics, recent studies suggest that relationships are labile, with animals interacting only over short periods to satisfy their immediate needs. Here I use data collected over 10 years on a community of chimpanzees, Pan troglodytes, at Ngogo, Kibale National Park, Uganda, to investigate whether male chimpanzees establish long-term social relationships and to determine the factors that affect variation in relationship quality and the stability of social bonds. Kinship and dominance rank influenced the quality of relationships. Maternal brothers and males of the same dominance rank class groomed each other more equitably than did unrelated males and males that were dissimilar in rank. In addition, males that formed strong social bonds groomed more equitably than did males that displayed weaker bonds. Social bonds were stable over time, with relationships in one year predicting those in subsequent years. Kinship and the quality of social relationships affected bond stability. Maternal half siblings and males that groomed each other equitably maintained longer-lasting bonds than did nonkin and males that groomed each other unevenly. Virtually all of the males established at least one enduring relationship with another individual. The most enduring bonds formed between a few pairs of maternal brothers and dyads that maintained balanced grooming interactions. These results indicate that male chimpanzees maintain long-lasting and equitable social bonds whose formation is affected by maternal kinship and the quality of social relationships.
Keywords: chimpanzee; Pan troglodytes; social behaviour; social relationship
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Nagy, K., Bodó, G., Bárdos, G., Harnos, A., & Kabai, P. (2009). The effect of a feeding stress-test on the behaviour and heart rate variability of control and crib-biting horses (with or without inhibition). Appl. Anim. Behav. Sci., 121(2), 140–147.
Abstract: Crib-biting is a form of oral stereotypy affecting 4-5% of horses. Once fixed, crib-biting is difficult to eliminate by behaviour therapy, however, its performance can be inhibited by collar or surgery treatment (modified Forssell's procedure). Although surgical intervention is widespread, the effects on stress coping in horses have not been studied. In the present study we evaluated changes in behaviour response and heart rate variability in 9 control, 10 crib-biting, 10 collar and 11 surgically treated horses in a feeding stress-test, in which a feeding-bowl was placed in front but out of the reach of the horses, from which tidbits were given 3 times. We found that stress triggers high oral activity, mainly cribbing in crib-biting horses, elevates other forms of oral activities in the inhibited groups and does not affect oral activities of controls. Instead of performing oral activities, control horses tended to target an unavailable feeding-bowl by pawing or head-tossing. Changes in stress level were indistinguishable in controls and crib-biters as heart rate variability returned to baseline values in both groups. In contrast, horses inhibited to perform crib-biting showed elevated stress level throughout the test period. Our results suggest that crib-biting may develop to cope with stress, and such coping function diminishes when inhibited.
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Lau, A. N., Peng, L., Goto, H., Chemnick, L., Ryder, O. A., & Makova, K. D. (2009). Horse Domestication and Conservation Genetics of Przewalski's Horse Inferred from Sex Chromosomal and Autosomal Sequences. Mol Biol Evol, 26(1), 199–208.
Abstract: Despite their ability to interbreed and produce fertile offspring, there is continued disagreement about the genetic relationship of the domestic horse (Equus caballus) to its endangered wild relative, Przewalski's horse (Equus przewalskii). Analyses have differed as to whether or not Przewalski's horse is placed phylogenetically as a separate sister group to domestic horses. Because Przewalski's horse and domestic horse are so closely related, genetic data can also be used to infer domestication-specific differences between the two. To investigate the genetic relationship of Przewalski's horse to the domestic horse and to address whether evolution of the domestic horse is driven by males or females, five homologous introns (a total of [~]3 kb) were sequenced on the X and Y chromosomes in two Przewalski's horses and three breeds of domestic horses: Arabian horse, Mongolian domestic horse, and Dartmoor pony. Five autosomal introns (a total of [~]6 kb) were sequenced for these horses as well. The sequences of sex chromosomal and autosomal introns were used to determine nucleotide diversity and the forces driving evolution in these species. As a result, X chromosomal and autosomal data do not place Przewalski's horses in a separate clade within phylogenetic trees for horses, suggesting a close relationship between domestic and Przewalski's horses. It was also found that there was a lack of nucleotide diversity on the Y chromosome and higher nucleotide diversity than expected on the X chromosome in domestic horses as compared with the Y chromosome and autosomes. This supports the hypothesis that very few male horses along with numerous female horses founded the various domestic horse breeds. Patterns of nucleotide diversity among different types of chromosomes were distinct for Przewalski's in contrast to domestic horses, supporting unique evolutionary histories of the two species.
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Fabritius, C. (2009). Sozialstruktur einer Herde Islandpferde bei Veränderung der Gruppenzusammenstellung. Ph.D. thesis, , Hannover.
Abstract: Die Domestikation des Pferdes begann wahrscheinlich etwa 5500 v. Chr. in
Südosteuropa. In Mitteleuropa traten circa 3000 v. Chr. die ersten Hauspferde auf. Grundsätzlich wird davon ausgegangen, dass sich die Ansprüche des Pferdes hinsichtlich der Lebensbedingungen, welche sich im Laufe der Evolution über Millionen von Jahren entwickelt haben, in der Obhut des Menschen nicht wesentlich geändert haben. Für Pferde typisch ist das Leben im Sozialverband, der Herde (Zeitler-Feicht 2008). Diese wird auch in den Leitlinien der Sachverständigengruppe tierschutzgerechte Pferdehaltung (10. November 1995) empfohlen, sofern es nicht durch zu häufigen Wechsel im Bestand zu einem Übermaß an Stress und agonistischen Aktionen kommt. Ziel der Arbeit war es, anhand eines nach der Literatur erstellten Ethogramms des Sozialverhaltens des Pferdes, herauszufinden, inwieweit Änderungen der Gruppenstruktur die sozialen Beziehungen beeinflussten. Die Fragestellung bezog sich auf eine Herde in Offenstallhaltung. Um die eventuellen Veränderungen der sozialen Interaktionen zu untersuchen, wurde erst die vorhandene Gruppenstruktur der Herde festgestellt. Danach wurde ein Individuum aus der Herde entfernt und ein anderes dazugestellt. Anschließend wurde die Gesamtgruppe in zwei Untergruppen geteilt und nach einem gewissen Zeitraum erneut zusammengeführt. Dabei wurden jeweils die Interaktionen der Pferde anhand des Ethogramms beobachtet, aufgezeichnet und protokolliert. Untersuchungsgegenstand war eine Herde Islandpferde, die in einer Ausgangsgruppe von 16 Tieren gehalten wurde. Die Beschreibung einer sozialen Ordnung im Allgemeinen und einer Rangordnung im Besonderen wird in vielen Studien ausschließlich auf der Basis der Beobachtung und Bewertung offensiv aggressiver Verhaltenselemente durchgeführt. Aggressives Verhalten muss hingegen im Gegensatz zu Verhaltensweisen, die die Anerkennung des sozialen Status des anderen Pferdes bedeuten, wie Abwenden oder Meiden, nicht notwendigerweise ein Anzeichen von Dominanz über ein anderes Tier bedeuten (Van Hoof u. Wensing 1987, Schilder 1988). Ein weiterer Aspekt dieser Arbeit sollte sein, eine Möglichkeit zu finden, die Sozialstruktur auch auf der Grundlage defensiver und soziopositiver Verhaltenselemente zu definieren. |
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Reid, P. J. (2009). Adapting to the human world: Dogs' responsiveness to our social cues. Behav. Process., 80(3), 325–333.
Abstract: Dogs are more skilful than a host of other species at tasks which require they respond to human communicative gestures in order to locate hidden food. Four basic interpretations for this proficiency surface from distilling the research findings. One possibility is that dogs simply have more opportunity than other species to learn to be responsive to human social cues. A different analysis suggests that the domestication process provided an opening for dogs to apply general cognitive problem-solving skills to a novel social niche. Some researchers go beyond this account and propose that dogs' co-evolution with humans equipped them with a theory of mind for social exchanges. Finally, a more prudent approach suggests that sensitivity to the behaviours of both humans and conspecifics would be particularly advantageous for a social scavenger like the dog. A predisposition to attend to human actions allows for rapid early learning of the association between gestures and the availability of food.
Keywords: Domestic dog; Social cognition; Communicative gestures
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Clutton-Brock, T. (2009). Cooperation between non-kin in animal societies. Nature, 462(7269), 51–57.
Abstract: Explanations of cooperation between non-kin in animal societies often suggest that individuals exchange resources or services and that cooperation is maintained by reciprocity. But do cooperative interactions between unrelated individuals in non-human animals really resemble exchanges or are they a consequence of simpler mechanisms? Firm evidence of reciprocity in animal societies is rare and many examples of cooperation between non-kin probably represent cases of intra-specific mutualism or manipulation.
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Verdolin, J. (2009). Gunnison’s prairie dog (Cynomys gunnisoni): testing the resource dispersion hypothesis. Beh. Ecol. Sociobiol., 63(6), 789–799.
Abstract: Few studies have experimentally tested the resource dispersion hypothesis (RDH). In this study, I tested whether space use and social organization of Gunnison’s prairie dog responded to changes in the dispersion and abundance of resources. Food manipulations were carried out during the reproductive and nonreproductive seasons across 2 years. Gunnison’s prairie dog adults responded to the experiments by decreasing territory size as food became patchier in space and time. Both males and females modified their home ranges, with no detectable difference between sexes, either prior to or during the experiments. As food became patchier in space and time, the spatial overlap of adults increased, whereas it decreased as food became more evenly dispersed. The average size of a group, defined as those individuals occupying the same territory, did not change significantly as a result of the experiments. Where changes in the composition and size of groups did occur, there was no indication that such changes were sex specific. Results from this study support critical components of the RDH and strongly suggest that patterns of space use and social structure in Gunnison’s prairie dogs are the result of individual responses to resource abundance and distribution.
Keywords: Biomedical and Life Sciences
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