Across mammals, increased body size is positively associated with lifespan. However, within species, this relationship is inverted. This is well illustrated in dogs (Canis familiaris), where larger dogs exhibit accelerated life trajectories: growing faster and dying younger than smaller dogs. Similarly, some age-associated traits (e.g., growth rate and physiological pace of aging) exhibit accelerated trajectories in larger breeds. Yet, it is unknown whether cognitive performance also demonstrates an accelerated life course trajectory in larger dogs. Here, we measured cognitive development and aging in a cross-sectional study of over 4000 dogs from 66 breeds using nine memory and decision-making tasks performed by citizen scientists as part of the Dognition project. Specifically, we tested whether cognitive traits follow a compressed (accelerated) trajectory in larger dogs, or the same trajectory for all breeds, which would result in limited cognitive decline in larger breeds. We found that all breeds, regardless of size or lifespan, tended to follow the same quadratic trajectory of cognitive aging—with a period of cognitive development in early life and decline in later life. Taken together, our results suggest that cognitive performance follows similar age-related trajectories across dog breeds, despite remarkable variation in developmental rates and lifespan.

中文翻译：

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年龄会影响家犬的认知能力，而不受平均品种寿命的影响。

在整个哺乳动物中，体型增加与寿命成正相关。但是，在物种内部，这种关系是相反的。这在犬类（犬类犬）中得到了很好的说明，大型犬表现出加速的生命轨迹：比小型犬更快地成长，并且更年轻。同样，一些与年龄相关的性状（例如生长速度和衰老的生理速度）在较大的品种中表现出加速的轨迹。然而，尚不清楚认知能力是否还证明了大型犬的生命过程轨迹加快。在这里，我们使用公民科学家作为“教义”的一部分执行的九项记忆和决策任务，对来自66个品种的4000多只狗进行了横断面研究，测量了认知发展和衰老项目。具体而言，我们测试了大型犬的认知特征是否遵循压缩（加速）轨迹，或所有犬种的轨迹均相同，这将导致大型犬的认知能力下降。我们发现，所有品种，无论大小或寿命，都倾向于遵循相同的二次认知衰老轨迹-早年的认知发展时期和后世的衰落时期。综上所述，我们的研究结果表明，尽管发育速度和寿命存在显着差异，但整个犬种的认知表现都遵循与年龄相关的相似轨迹。