Selection on behavioural traits holds a prominent role in the domestication of animals. Specifically, a reduction of the fear response is considered a key component, with domesticated animals expressing lower levels of fear towards novelty than their wild counterparts. Previous work has suggested that this is caused by a delay in the onset of fearful behaviour during early ontogeny in domesticated canids. However, it remains unclear how the developmental timing of initial fear expression affects fearfulness later in development. Here we present the first extended examination of the development of fear behaviour in wolves and dogs, using repeated novel object tests between six and 26 weeks of age. Contrary to expectations, fear of novelty did not change in wolves with age, but dogs expressed decreased latency to approach a novel object with age, resulting in a species difference at the end of the measured period. Our results thereby suggest that differences in fear of novelty between wolves and dogs are not caused by a domestication driven shift in the first onset of fear response. Instead we suggest that differences in fear expression between wolves and dogs are caused by a loss of sensitivity towards novelty with age in dogs.
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