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Although domestic dogs were the first domesticated species, the nature of dog domestication remains a topic of ongoing debate. In particular, brain and behavior changes associated with different stages of the domestication process have been difficult to disambiguate. Most modern Western breed dogs possess highly derived physical and behavioral traits because of intense artificial selection for appearance and function within the past 200 years. In contrast, premodern dogs, including primitive/ancient breeds, village dogs, and New Guinea Singing Dogs, have undergone less intensive artificial selection and retain more ancestral characteristics. Consequently, comparisons between modern and premodern dogs can shed light on brain and behavior changes that have occurred recently in the domestication process. Here, we addressed this question using a voxel-based morphometry analysis of structural MRI images from 72 modern breed dogs and 13 premodern dogs (32 females). Modern breed dogs show widespread expansions of neocortex and reductions in the amygdala and other subcortical regions. Furthermore, cortical measurements significantly predicted individual variation in trainability, while amygdala measurements significantly predicted fear scores. These results contrast with the long-standing view that domestication consistently involves reduction in brain size and cognitive capacity. Rather, our results suggest that recent artificial selection has targeted higher-order brain regions in modern breed dogs, perhaps to facilitate behavioral flexibility and close interaction and cooperation with humans.
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This content will become publicly available on November 1, 2026
What Does That Head Tilt Mean? Brain Lateralization and Sex Differences in the Processing of Familiar Human Speech by Domestic Dogs
Does the head tilt observed in many domesticated dogs index lateralized language processing? To answer this question, the present study evaluated household dogs responding to four conditions in which owners provided an increasing number of communicative cues. These cues ranged from no communicative/affective cues to rich affective cues coupled with dog-directed speech. Dogs’ facial responses were first coded manually using the Dog Facial Action Coding System (DogFACS), followed by an in-depth investigation of head tilt behavior, in which AI-based automated analysis of head tilt and audio analysis of acoustic features extracted from communicative cues were implemented. In a sample of 103 dogs representing seven breed groups and mixed-breed dogs, we found significant differences in the number of head tilts occurring between conditions, with the most communicative (last) condition eliciting the most head tilts. There were also significant differences in the direction of the head tilts and between sex groups. Dogs were more likely to tilt their heads to the right, and neutered male dogs were more likely to tilt their heads than spayed female dogs. The right-tilt bias is consistent with left-hemisphere language processing in humans, with males processing language in a more lateralized manner, and females processing language more bilaterally—a pattern also observed in humans. Understanding the canine brain is important to both evolutionary research through a comparative lens, and in understanding our interspecies relationship.
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- Award ID(s):
- 2238071
- PAR ID:
- 10655484
- Publisher / Repository:
- Animals
- Date Published:
- Journal Name:
- Animals
- Volume:
- 15
- Issue:
- 21
- ISSN:
- 2076-2615
- Page Range / eLocation ID:
- 3179
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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