August 01, 2009

The shape of dogs' heads and their performance

A nice study establishing a relationship between dogs' abilities and (i) their modus operandi (independent/co-operating in proximity with humans), or (ii) their head shape (brachycephalic vs. dolichocephalic).

It would be interesting to do similar studies in humans. I seriously doubt that a proposal for the study of the human cephalic index, or cranial shape, with any type of human ability would have a high chance of getting funded.

It is true that a lot of nonsense on the topic was published by statistically naive anthropologists of past decades, but this is no reason to refrain from it forever.

We can now do 3D scans of human heads, we have the fast computers and sophisticated statistical methods to analyze large quantities of anthropometric data. It's a shame that timidity is keeping anthropologists from exploring the plethora of opportunities for exciting research in the area of anthropometry-psychology interactions.

Behav Brain Funct. 2009 Jul 24;5(1):31.

Effects of selection for cooperation and attention in dogs.

Gacsi M, McGreevy P, Kara E, Miklosi A.

ABSTRACT: BACKGROUND: It has been suggested that the functional similarities in the socio-cognitive behaviour of dogs and humans emerged as a consequence of comparable environmental selection pressures. Here we use a novel approach to account for the facilitating effect of domestication in dogs and reveal that selection for two factors under genetic influence (visual cooperation and focused attention) may have led independently to increased comprehension of human communicational cues. METHOD: In Study 1, we observed the performance of three groups of dogs in utilizing the human pointing gesture in a two-way object choice test. We compared breeds selected to work while visually separated from human partners (N=30, 21 breeds, clustered as independent worker group), with those selected to work in close cooperation and continuous visual contact with human partners (N=30, 22 breeds, clustered as cooperative worker group), and with a group of mongrels (N=30). Secondly, it has been reported that, in dogs, selective breeding to produce an abnormal shortening of the skull is associated with a more pronounced area centralis (location of greatest visual acuity). In Study 2, breeds with high cephalic index and more frontally placed eyes (brachycephalic breeds, N=25, 14 breeds) were compared with breeds with low cephalic index and laterally placed eyes (dolichocephalic breeds, N=25, 14 breeds). RESULTS: In Study 1, cooperative workers were significantly more successful in utilizing the human pointing gesture than both the independent workers and the mongrels. In study 2, we found that brachycephalic dogs performed significantly better than dolichocephalic breeds. DISCUSSION: After controlling for environmental factors, we have provided evidence that at least two independent phenotypic traits with certain genetic variability affect the ability of dogs to rely on human visual cues. This finding should caution researchers against making simple generalizations about the effects of domestication and on dog-wolf differences in the utilization of human visual signals.


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