Roberts Anna Ilona, Roberts Sam George Bradley
McDonald Institute for Archaeological Research, University of Cambridge, 13A Fitzwilliam Street, Cambridge, CB2 1QH, UK.
School of Natural Sciences and Psychology, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK.
Anim Cogn. 2025 Jul 14;28(1):58. doi: 10.1007/s10071-025-01980-z.
An important element in understanding the evolution of human sociality is to understand the factors that governed the evolution of social organisation in our closest living relatives. The 'social brain hypothesis' proposes that the complex social world of primates is especially cognitively demanding, and that this imposed intense selection pressure for increasingly large brains. Group size in primates is strongly correlated with brain size but exactly what makes larger groups more 'socially complex' than smaller groups is still poorly understood. Chimpanzees and Gorillas are among our closest living relatives and they exhibit remarkable diversity in various aspects of their social organisation both within and across species. They are thus excellent species in which to investigate patterns of sociality and social complexity in primates, and to inform models of human social evolution. We propose a program of research that will provide the first systematic insight into how social structure differs in small, medium and large groups of Chimpanzees and Gorillas, to explore what makes larger groups more socially complex than smaller groups. Further, we propose to investigate how these variations in social structure in different size groups are affected by the social organisation of the species. Chimpanzees live in a fluid fission-fusion social system, whereas Gorillas have more stable, cohesive groups. To carry out both the within and between species comparisons, we advocate use of social network analysis, which provides a novel way to describe and compare social structure. This program of research will therefore lead to a new, systematic way of comparing social complexity across species, something that is lacking in current comparative studies of social structure. Considering that hominins were likely characterized by a fission-fusion social structure, comparing the social complexity of such systems with that of more stable groups may yield valuable insights into the evolution of human sociality.
理解人类社会性进化的一个重要因素是了解那些支配我们现存近亲社会组织进化的因素。“社会脑假说”提出，灵长类动物复杂的社会世界对认知的要求极高，这对大脑不断增大施加了强大的选择压力。灵长类动物的群体规模与大脑大小密切相关，但究竟是什么使得较大群体比小群体更具“社会复杂性”，目前仍知之甚少。黑猩猩和大猩猩是我们现存的近亲，它们在社会组织的各个方面，无论是种内还是种间，都表现出显著的多样性。因此，它们是研究灵长类动物社会性模式和社会复杂性，并为人类社会进化模型提供参考的优秀物种。我们提出了一项研究计划，该计划将首次系统地洞察黑猩猩和大猩猩的小群体、中等群体和大群体的社会结构差异，以探究是什么使得较大群体比小群体更具社会复杂性。此外，我们还打算研究不同规模群体的社会结构变化是如何受到物种社会组织影响的。黑猩猩生活在一个流动的裂变 - 融合社会系统中，而大猩猩的群体则更稳定、更具凝聚力。为了进行种内和种间比较，我们提倡使用社会网络分析，它为描述和比较社会结构提供了一种全新的方法。因此，这项研究计划将带来一种全新的、系统的跨物种比较社会复杂性的方法，这是当前社会结构比较研究中所缺乏的。鉴于原始人类可能具有裂变 - 融合的社会结构，将这种系统的社会复杂性与更稳定群体的社会复杂性进行比较，可能会为人类社会性的进化提供有价值的见解。
