Institute of Biology, University of Neuchâtel, Emile-Argand 11, 2000, Neuchâtel, Switzerland.
Department of Zoology, Stockholm University, Svante Arrheniusväg 18 B, Stockholm, Sweden.
Nat Commun. 2020 Dec 21;11(1):6423. doi: 10.1038/s41467-020-20130-2.
It is generally agreed that variation in social and/or environmental complexity yields variation in selective pressures on brain anatomy, where more complex brains should yield increased intelligence. While these insights are based on many evolutionary studies, it remains unclear how ecology impacts brain plasticity and subsequently cognitive performance within a species. Here, we show that in wild cleaner fish (Labroides dimidiatus), forebrain size of high-performing individuals tested in an ephemeral reward task covaried positively with cleaner density, while cerebellum size covaried negatively with cleaner density. This unexpected relationship may be explained if we consider that performance in this task reflects the decision rules that individuals use in nature rather than learning abilities: cleaners with relatively larger forebrains used decision-rules that appeared to be locally optimal. Thus, social competence seems to be a suitable proxy of intelligence to understand individual differences under natural conditions.
普遍认为，社会和/或环境复杂性的变化会导致大脑解剖结构的选择压力发生变化，而更复杂的大脑应该会产生更高的智力。虽然这些观点是基于许多进化研究得出的，但生态如何影响物种内部的大脑可塑性以及认知表现仍不清楚。在这里，我们表明，在野外清洁鱼（Labroides dimidiatus）中，在短暂奖励任务中表现出色的个体的大脑前部大小与清洁鱼密度呈正相关，而小脑大小与清洁鱼密度呈负相关。如果我们考虑到在这个任务中的表现反映了个体在自然环境中使用的决策规则，而不是学习能力，那么这种意外的关系可能就可以解释了：相对较大脑前部的清洁鱼使用的决策规则似乎是局部最优的。因此，社会能力似乎是理解自然条件下个体差异的智力的合适替代指标。
