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PloS one2009; 4(3); e4888; doi: 10.1371/journal.pone.0004888

Adult-young ratio, a major factor regulating social behaviour of young: a horse study.

Abstract: Adults play an important role in regulating the social behaviour of young individuals. However, a few pioneer studies suggest that, more than the mere presence of adults, their proportions in social groups affect the social development of young. Here, we hypothesized that aggression rates and social cohesion were correlated to adult-young ratios. Our biological model was naturally-formed groups of Przewalski horses, Equus f. przewalskii, varying in composition. Results: We investigated the social interactions and spatial relationships of 12 one- and two-year-old Przewalski horses belonging to five families with adult-young ratios (AYR) ranging from 0.67 to 1.33. We found striking variations of aggression rates and spatial relationships related to the adult-young ratio: the lower this ratio, the more the young were aggressive, the more young and adults segregated and the tighter the young bonded to other young. Conclusions: This is the first study demonstrating a correlation between adult-young ratios and aggression rates and social cohesion of young individuals in a naturalistic setting. The increase of aggression and the emergence of social segregation in groups with lower proportions of adults could reflect a related decrease of the influence of adults as regulators of the behaviour of young. This social regulation has both theoretical and practical implications for understanding the modalities of the influence of adults during ontogeny and for recommending optimal settings, as for instance, for schooling or animal group management.
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Publication Date: 2009-03-18 PubMed ID: 19293930PubMed Central: PMC2654111DOI: 10.1371/journal.pone.0004888Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research study focuses on how the ratio of adults to young members in a group can influence social behaviour, specifically within groups of Przewalski horses. It was found that lower ratios of adults led to increased aggression and social segregation among the younger members.

Research Objectives and Hypothesis

  • The research primarily aimed to establish if there was a correlation between the adult-to-young ratio in horse groups and the rate of aggression and social cohesion among the young horses.
  • The hypothesis proposed was that higher aggression rates and less social cohesion were related to lower adult-young ratios.

Methodology

  • To test the hypothesis, the researchers studied the social interactions and spatial relationships of 12 one- and two-year-old Przewalski horses.
  • These horses belonged to five families with varying adult-young ratios ranging between 0.67 to 1.33.

Results

  • The results showed significant variations in aggression rates and spatial relationships, connected to the adult-young ratio.
  • It was noted that a lower ratio resulted in the young becoming more aggressive. Additionally, there was more segregation between young and adult horses, and the young formed stronger bonds with their own age group.

Conclusions and Implications

  • This is the first known study showing a correlation between adult-young ratios and aggression rates and social cohesion among young horses in a naturalistic setting.
  • The study concluded that the increase in aggression and social segregation in groups with fewer adults could be due to a decreased influence of adults in managing the behavior of the young.
  • The findings of this study bear significance for both theoretical understanding of adult influence during ontogeny and practical applications in settings like schooling or animal group management where the adult-young ratio is a factor.

Cite This Article

APA
Bourjade M, de Boyer des Roches A, Hausberger M. (2009). Adult-young ratio, a major factor regulating social behaviour of young: a horse study. PLoS One, 4(3), e4888. https://doi.org/10.1371/journal.pone.0004888

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 4
Issue: 3
Pages: e4888
PII: e4888

Researcher Affiliations

Bourjade, Marie
  • Université de Rennes 1, Laboratoire d'Ethologie Animale et Humaine, Centre National de la Recherche Scientifique, Rennes, France. marie.bourjade@gmail.com
de Boyer des Roches, Alice
    Hausberger, Martine

      MeSH Terms

      • Age Factors
      • Animals
      • Behavior, Animal
      • Horses / physiology
      • Social Behavior

      Conflict of Interest Statement

      The authors have declared that no competing interests exist.

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      Citations

      This article has been cited 10 times.
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