The domestication syndrome describes a set of correlated changes in animals—spanning morphology, physiology, and behavior—that arise during domestication. In dogs, these behaviors include prosocial traits such as sociability and playfulness as well as reactive traits like fearfulness and aggression. However, whether these traits remain tightly linked in all dogs has been debated.
Christina Hansen Wheat and colleagues (2019) conducted a large-scale quantitative analysis of 76,158 dogs from 78 breeds. They measured correlations among key prosocial and reactive behaviors to test whether domestication-linked traits remain bundled together in modern populations.
The results showed that ancient breeds—those closer to dogs’ early evolutionary history and with more wolf admixture—displayed stronger correlations between prosocial and reactive behaviors. By contrast, modern breeds, shaped by recent selective pressures, showed weaker or decoupled correlations. This indicates that modern breeding practices have disrupted the natural behavioral linkages associated with domestication, allowing traits like playfulness, fear, and aggression to evolve more independently.
These findings suggest that recent shifts in selection pressures—particularly in the last few centuries of breed development—have fundamentally altered how domestication-related behaviors are expressed. This highlights how human-driven breeding has reshaped not only dogs’ appearance but also the deep behavioral structures forged during domestication.
Source: Wheat, C. H., Fitzpatrick, J., Rogell, B., & Temrin, H. (2019). Behavioural correlations of the domestication syndrome are decoupled in modern dog breeds. Nature Communications, 10. Published June 3, 2019.
