優位なヒヒは夜間の休息が少ないことを発見(Heavy is the head that wears the crown: study finds dominant baboons miss out on restful nights)

2025-12-12 スウォンジー大学

スウォンジー大学の研究チームは、野生ヒヒの社会的地位と睡眠の関係を初めて明らかにした。南アフリカのチャクマヒヒ群をGPSと加速度計付き首輪で追跡した結果、群れ内で高い地位にあるヒヒほど夜間の休息時間が短く、睡眠も断片的であることが分かった。研究者は、ヒヒは夜間でも集団で同調して休息・覚醒する傾向があるが、高位個体は周囲に多くの仲間が近くにいるため互いに影響を及ぼし合い、夜間の覚醒が増えると説明している。これは、人間同様に睡眠の質が健康や意思決定に影響する可能性を示唆するもので、日中の社会的優位性が夜間の休息の「代償」を伴うことを示す初のフィールドデータとなる。研究成果は Current Biology に掲載された。

<関連情報>

優位なヒヒは夜間に中断が多くなり、休息が少なくなる Dominant baboons experience more interrupted and less rest at night

Marco Fele ∙ Charlotte Christensen ∙ Anna M. Bracken ∙ … ∙ Marina Papadopoulou ∙ Ines Fürtbauer ∙ Andrew J. King

Current Biology  Published:December 12, 2025

DOI:https://doi.org/10.1016/j.cub.2025.10.028

Graphical abstract

優位なヒヒは夜間の休息が少ないことを発見(Heavy is the head that wears the crown: study finds dominant baboons miss out on restful nights)

Highlights

  • Baboons of higher social dominance have more interrupted and less nighttime rest
  • Baboons of similar social dominance rank are more synchronized
  • Baboons of similar dominance rank influence each other’s rest behavior more
  • Spatial proximity probably underlies rest synchrony and influence

Summary

Sleep is a fundamental biological process.1,2 The amount and quality of sleep individuals get can impact various aspects of human and non-human animal health,1 ultimately affecting fitness.3 For wild animals that sleep in groups, individuals may disturb one another’s sleep,4,5 but this aspect of social sleep has been understudied due to methodological challenges.6,7,8 Here, using nighttime rest (absence of bodily movements) as a proxy for sleep, we test the hypothesis that an individual’s social dominance affects nighttime rest in a troop of wild, highly hierarchical8,9 chacma baboons (Papio ursinus). First, we show that the troop’s nighttime rest (determined by 40 Hz acceleration data) is highly synchronized. Next, we link nighttime rest dynamics to daytime spatial networks and dominance hierarchy (from 1 Hz GPS data and direct observations). We show that baboon nighttime states (activity and rest) are more synchronized between similarly ranked individuals and, unexpectedly, that more dominant baboons experience more interrupted and less nighttime rest than lower-ranked baboons. We propose that this hierarchy effect is explained by higher-ranked baboons resting closer to more group members, which leads them to exert a greater influence on each other’s nighttime behavior compared with lower-ranked individuals. Our study provides the first evidence for the impact of social hierarchies on aspects of sleep in a wild primate, suggesting that dominance status may impose trade-offs between social rank and the quality and quantity of sleep.

1903自然環境保全
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