2025-08-07 マックス・プランク研究所
<関連情報>
- https://www.mpg.de/25119311/0730-evan-it-s-not-just-about-size-150495-x
- https://www.cell.com/current-biology/fulltext/S0960-9822(25)00872-3
メスのマウンテンゴリラは非アルファオスより上位にランクされる Female mountain gorillas can outrank non-alpha males
Nikolaos Smit ∙ Martha M. Robbins
Current Biology Published:August 7, 2025
DOI:https://doi.org/10.1016/j.cub.2025.07.006
Graphical abstract
Highlights
- Female mountain gorillas can outrank males despite being half their size
- In our study, females won 28% of agonistic interactions against adult non-alpha males
- Females had feeding priority over males they outranked
Summary
Males have been long assumed to strictly outrank females in all but a few mammals, potentially due to male-biased size dimorphism emerging from male-male competition and female mate choice. However, recent work questions these traditional views, suggesting that intersexual power varies along a continuum from strictly male- to strictly female-biased and is not a static species attribute.1,2,3,4 We used a 25-year dataset to examine the intersexual power dynamics in wild mountain gorillas, considered a prominent example of strict male power. Although the highest-ranking individual in each of the four study groups was male, 88% of females outranked at least one adult male in multi-male groups. Females won 28% of agonistic interactions against non-alpha males, predominantly when these males were young adults or old. Our results did not support that females gain power over males due to mating-based leverage, as a byproduct of male-male competition, or due to female-female support, but they suggested that females may gain power over non-alpha males due to alpha male support and by leveraging commodities not directly linked to mating. Females always had feeding priority on a valued monopolizable resource over non-alpha males they outranked and, in half of the cases, over non-alpha males overall, highlighting a functional component of female empowerment. Our study questions the “male power archetype” assumption in a hominid that exhibits extreme male-biased sexual size dimorphism5,6 and, thus, it calls for future work to investigate similar long-standing assumptions regarding the evolutionary origins of intersexual relationships across species.
