Dogs are a great study system for behavior because you have a set of breeds that have undergone recent, strong, and divergent selection for specific behavioral characteristics over a very short period of time (~15ky—we are evolution here, so anything on the order of thousands of years is considered recent). This has also resulted in a great deal of diversity, not only in behavior, but also in morphology and lifespan.

Careau and colleagues tie these strands together:

Here we tested whether proactive [dog] personalities (high levels of activity, boldness, and aggression) are related to a fast “pace of life” (high rates of growth, mortality, and energy expenditure). Data from the literature provide preliminary evidence that artificial selection on dogs (through domestication) generated variations in personality traits that are correlated with life histories and metabolism. We found that obedient (or docile, shy) breeds live longer than disobedient (or bold) ones and that aggressive breeds have higher energy needs than unaggressive ones.

They posit a correlated response to selection on personality as the explanation for these changes in life-history parameters.

There is something fundamentally Darwinian in this study: looking at artificial and unconscious selection by humans as a complex evolutionary process.

• Careau et al. (2010) The Pace of Life under Artificial Selection: Personality, Energy Expenditure, and Longevity Are Correlated in Domestic Dogs. Am Nat doi:10.1086/652435

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