Polygenic adaptation signals reveal selection on key behavioral traits early in dog domestication history.

Polygenic adaptation signals in two canine genomic datasets (1,987 and 722 individuals) show the strongest, shared selection on pro-social behaviors—especially reduced owner-directed aggression and non-social fear—across dog lineages.

• Why it matters: The timing and lineage-specific locations of artificial selection on dog behavior versus morphology are unclear, limiting how we interpret domestication’s earliest genetic changes.
• What they did: The study grouped breeds into Asian Spitz, African-Middle Eastern, and European Modern lineages, integrated genomic variation with 36 behavioral and four morphological traits, and tested polygenic adaptation using pairwise comparisons and PolyGraph.
• The result: Pro-social shifts were more consistently shared than morphological shifts; PolyGraph inferred ancestral decreases in aggression and non-social fear, with ancient trait scores matching these patterns and showing early differentiation from wolves.

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