The decisive role of subordination in social hierarchy in weanling mice and young children

Abstract

Social hierarchy plays important roles in maintaining social structures. Despite similarity in concept, frameworks of human hierarchy have seldom been investigated in parallel with other animals. Moreover, the importance of subordination in hierarchical formation has been largely underestimated in previous research. Here we established, compared, and investigated hierarchy in children and weanling mice. Temperament assessments suggested that children who are less persistent, low emotional intensity, and withdrew easily were more likely to be subordinate in competitive scenarios independent of task characteristics and interaction experiences. The tube test further showed that conflicts between mice were not resolved by winner approach but by loser withdrawal, which was mainly determined by intrinsic subordinate status regardless of opponents. Our study presents evolutionary conserved hierarchical relationships in young and a critical role of the intrinsic subordinate characteristics in hierarchical determination. These findings provide a new perspective on social interactions with potential implications for preschool education.

Positive correlations between social hierarchy and memory in weaning mice and young children

“…Based on our previous study 32 , a social hierarchy in weanling mice can be established in mice in a cage by tube test (Figure S1). To study the correlation between social ranks and memory ability, we first conducted the novel object recognition (NOR) test with a 1-hour interval between training and test sessions to evaluate short-term recognition memory in weanling mice 45 .…”

“…Based on the experimental design in the mouse tube test, we first arranged the young children into groups of four and established their social hierarchies by evaluating their behaviors while they played a competitive bunny game with a round robin design. The bunny game has been used as a comparable task to the mouse tube test in a previous study 32 . We next used the Picture memory subtest (for recognition memory) and Zoo subtest (for spatial working memory) from the Wechsler Preschool and Primary Scale of Intelligence through one-by-one testing to compare memory ability between 1 st -rank and 4 th -rank children (n=82) (Figure 3A) 50 .…”

“…The working memory index (WMI) that integrated two memory subtests showed a significantly higher score in 1 st -rank children than in 4 th -rank children (Figure 3B). In addition to the bunny game evaluation conducted in a well-designed experimental context, we also asked the preschool teachers to evaluate the children's social dominance level according to their daily observations using the Social Dominance Rating Scale (Figure 3A), which has been shown to be consistent with the social ranks by the bunny game 32,51 . The dominance levels in these 82 children showed trends correlated with memory scores in both Picture memory and Zoo subtests (Figure S5C and D).…”

“…On the other hand, tube test, in which one mouse forces its opponent backward out of a tube, is relatively easy for mice to complete and has been used largely to study social dominance [29][30][31] . Since the assay only requires mice moving forward and backward inside the tube, it presents as a platform to investigate the relationship between social hierarchy and other traits not only in adult but also in young animals 28,32 .…”

“…The findings from these two species therefore could complement each other and provide important information from different perspectives. By taking advantage of this comparative and complementary approach to study social dominance behaviors, our recent study has presented comparable social ranks between young human children and weanling mice and further revealed important intrinsic factors involved in the early formation of social hierarchy 32 . This study, however, did not identify the potential role of learning and memory in hierarchical formation in mice and children.…”