How do repeated victories or defeats change an animal’s willingness to fight?

Direct experience with victory or defeat significantly influences an animal’s subsequent willingness to engage in aggressive behavior. Across diverse species, ranging from crickets to chimpanzees, individuals that lose fights regularly become increasingly less likely to initiate future attacks.1

These changes in behavior are fundamental to the formation of dominance hierarchies and are driven by several factors:

• Neuroendocrine Changes: Fighting experience has a marked effect on brain biochemistry, particularly within the limbic system. For instance, in subordinates, there is often a longer-term elevation of serotonin systems, which is associated with reduced aggressiveness.2
• Conditioning and Learning: These behavioral shifts may result from reward-based processes where the animal learns from the outcomes of its social interactions.1
• Postural Adjustments: In many species, such as crustaceans, a hierarchical relationship is established where the victor adopts a dominant posture, while the loser adopts a submissive posture and actively avoids future conflicts.2

Ultimately, these effects represent a complex interaction between an animal's social history and its physiological state, determining whether it will continue to fight or withdraw from potential confrontations.12