Comparative study of the function of brain-body system in social behaviour in birds

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H02653
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Experimental psychology
• Research Institution: Keio University
• Principal Investigator: Izawa Ei-Ichi 慶應義塾大学, 文学部(三田), 教授 (10433731)
• Co-Investigator(Kenkyū-buntansha): 茂木 一孝 麻布大学, 獣医学部, 准教授 (50347308)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 情動 / 進化 / 利他性 / 脳 / 自律神経系

Outline of Final Research Achievements

This research project aimed to examine the social function and physiological mechanisms of social behaviour of crows. We found primarily three findings. First, analysis of long-term behavioural data from group-housed crows suggested that allopreening within same-sex individuals functions as a dominance signal function. Second, analysis of inter-individual distance in a social interaction involving three individuals revealed that the presence of the 1st dominant male caused the distance between the other two individuals to be close. Third, based on EEG data recorded from freely interacting crows, heart-rate variability analysis uncovered that subordinate crows showed the lower heart rate and higher rMSSD during the interaction with dominant birds than during being alone, indicating the involvement of the parasympathetic autonomic nervous system in social interaction of subordinate birds.

Free Research Field

動物心理学

Academic Significance and Societal Importance of the Research Achievements

哺乳類とは異なる進化を遂げた鳥類カラスは，社会行動の心理・生理メカニズムを進化の視点で理解する上でユニークで重要なモデルである．本研究では，カラスの社会行動について，群れ生態における役割，行動調節機構，神経調節機構，これら３つの側面から調べた．その結果，カラスが同性個体同士で行う羽繕い（毛繕い）は行為者の優位性誇示の役割があること，群れ内では最優位（１位）オスが近づくとそれ以外の個体間の距離が接近すること，優位オスと対峙中の劣位オスの心拍は低下し，副交感神経の作用があることを発見した．社会行動はその機能が独自に進化しながらも，身体と脳という共通の生物基盤をもつことの一端が明らかになった．