Human-directed play behaviour is a distinct behavioural feature of domestic dogs. But the role that artificial selection for contemporary dog breeds has played for human-directed play behaviour remains elusive. Here, we investigate how human-directed play behaviour has evolved in relation to the selection for different functions, considering processes of shared ancestry and gene flow among the different breeds. We use the American Kennel Club (AKC) breed group categorization to reflect the major functional differences and combine this with observational data on human-directed play behaviour for over 132 breeds across 89 352 individuals from the Swedish Dog Mentality Assessment project. Our analyses demonstrate that ancestor dogs already showed intermediate levels of human-directed play behaviour, levels that are shared with several modern breed types. Herding and Sporting breeds display higher levels of human-directed play behaviour, statistically distinguishable from Non-sporting and Toy breeds. Our results suggest that human-directed play behaviour played a role in the early domestication of dogs and that subsequent artificial selection for function has been important for contemporary variation in a behavioural phenotype mediating the social bond with humans.

以人为主导的游戏行为是家犬的独特行为特征。但是，对当代犬种进行人工选择对于人类指导的游戏行为所起的作用仍然难以捉摸。在这里，我们考虑到不同品种之间的共同血统和基因流，我们研究了以人为主导的游戏行为是如何与选择不同功能有关的。我们使用美国养犬俱乐部（AKC）品种组的分类来反映主要的功能差异，并将其与来自瑞典狗心理评估项目的89 352个个体中超过132个品种的人类定向游戏行为的观察数据结合起来。我们的分析表明，祖先犬已经显示出中等水平的人类主导的游戏行为，与几种现代品种类型共有的水平。牧民和体育品种表现出更高水平的以人为主导的游戏行为，从统计上可与非体育和玩具品种区分开。我们的研究结果表明，以人为主导的游戏行为在犬的早期驯养中发挥了作用，随后对功能的人为选择对于调节与人之间的社会纽带的行为表型的当代变异非常重要。