A Dog's Size and Head Shape Predicts Its Behavior

Keit

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Interesting findings in this paper.


The dog's height predicted a number of aspects of the dog's behavioral tendencies. It may be a surprise to many people to find that shorter dogs were found to be generally more aggressive than taller dogs. In addition the taller dogs tended to show more affection, cooperation, and playfulness with humans.

The dog's weight also predicted certain personality characteristics. Heavier dogs tended to be bolder, more inquisitive, and attentive. Lighter dogs tended to be more cautious and fearful.

Head shape also predicted some differences in temperament. The brachycephalic dogs seem to be more engaged with their owners with a higher interest in human-directed play. On the other hand these short-faced dogs were more defensive when faced with a difficult to interpret situation (such as seeing a person dressed like a ghost). The dolichocephalic dogs seem to be less likely to engage in object play, especially with unfamiliar humans. However these long-faced dogs were not as easily startled and recovered more quickly when an unexpected event occurred.

These are just the major findings. However the overall conclusion is that the height, weight, and head shape of dogs can predict certain important behavioral and temperament variables including certain aspects of aggression, fearfulness, sociability and affection. In general it supports Sigmund Freud's contention that "Physiology is destiny," at least when it comes to the size and shape of dogs.
 
If such traits can be noted in dogs which have been intensively "bred up", I would say that much the same is true for other creatures including humans: physiology has a relationship to psychology and possibly even soul dynamics. The Cs once remarked that the soul "marries" with the genetics, so to say.

It is also well know that certain genetics are connected to susceptibility to certain conditions, so that plays a part as well.

In French, different breeds of dogs are called "races" and it is probably the most useful way the term is defined. If any group practices endogamy, they soon become a "race" even if they look a lot like other groups.

I read Carleton Coon's book entitled "The Races of Europe" where he discussed at great length different groups of people who had been relatively endogamous just within Europe, and it really is interesting to see how they became rather like you describe the dog breeds above: exemplars for this or that characteristics.
 
I read Carleton Coon's book entitled "The Races of Europe" where he discussed at great length different groups of people who had been relatively endogamous just within Europe, and it really is interesting to see how they became rather like you describe the dog breeds above: exemplars for this or that characteristics.

What you say makes a lot of sense. But as we know, this is an extremely sensitive topic, especially in the current social climate. Recently I listened to this interview with Haidt (highly recommended!), and he mentioned (starting from 39 min) how nowadays some professors refuse to teach certain subjects, like Intelligence, out of fear of being reported. He says that in The Basic Introduction to Cognitive Psychology, where intelligence is almost always a day or a week in the curriculum, they just cut it. Because of the findings of heritability.
 
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If such traits can be noted in dogs which have been intensively "bred up", I would say that much the same is true for other creatures including humans: physiology has a relationship to psychology and possibly even soul dynamics. The Cs once remarked that the soul "marries" with the genetics, so to say.

It is also well know that certain genetics are connected to susceptibility to certain conditions, so that plays a part as well.

In French, different breeds of dogs are called "races" and it is probably the most useful way the term is defined. If any group practices endogamy, they soon become a "race" even if they look a lot like other groups.

I read Carleton Coon's book entitled "The Races of Europe" where he discussed at great length different groups of people who had been relatively endogamous just within Europe, and it really is interesting to see how they became rather like you describe the dog breeds above: exemplars for this or that characteristics.
During the Siberian Fox Experiment a group of foxes were selectively bred for personality features that make them better pets (better temperament,more friendly to humans).The experiment took place over 20 years and by the end the foxes had different physical characteristics to match their personality,like shorter snouts for example.
 
Here's some info on the Silver Fox Experiment. One of the issues I had with this experiment is that they didn't, as far as I remember, control for the fact that the Foxes were held in captivity outside of their selective breeding program.

It is not possible here to do justice to all of the results this almost six-decade-long experiment has produced. Here I touch on some of the most salient (see Trut 1999, Trut et al. 2009 and Dugatkin and Trut 2017 for more). Starting from what amounted to a population of wild foxes, within six generations (6 years in these foxes, as they reproduce annually), selection for tameness, and tameness alone, produced a subset of foxes that licked the hand of experimenters, could be picked up and petted, whined when humans departed, and wagged their tails when humans approached. An astonishingly fast transformation. Early on, the tamest of the foxes made up a small proportion of the foxes in the experiment: today they make up the vast majority.

Belyaev was correct that selection on tameness alone leads to the emergence of traits in the domestication syndrome. In less than a decade, some of the domesticated foxes had floppy ears and curly tails (Fig. 2). Their stress hormone levels by generation 15 were about half the stress hormone (glucocorticoid) levels of wild foxes. Over generations, their adrenal gland became smaller and smaller. Serotonin levels also increased, producing “happier” animals. Over the course of the experiment, researchers also found the domesticated foxes displayed mottled “mutt-like” fur patterns, and they had more juvenilized facial features (shorter, rounder, more dog-like snouts) and body shapes (chunkier, rather than gracile limbs) (Fig. 3). Domesticated foxes like many domesticated animals, have longer reproductive periods than their wild progenitors. Another change associated with selection for tameness is that the domesticated foxes, unlike wild foxes, are capable of following human gaze as well as dogs do (Hare et al. 2005). In a recent paper, a “hotspot” for changes associated with domestication has been located on fox chromosome 15 (Kukekova et al. 2018). SorCS, one gene in this hotspot, is linked with synaptic plasticity, which itself is associated with memory and learning, and so together these studies are helping us better understand how the process of domestication has led to important changes in cognitive abilities.

A snippet about the genetics involved in the change.

Right from the start of the experiment, Belyaev hypothesized that the process of domestication was in part the result of changes in gene expression patterns—when genes “turn on” and “turn off” and how much protein product they produce. A recent study examining expression patterns at the genome level, in both domesticated foxes and a second line of foxes that has been under long-term selection for aggressive, rather than tame, behavior, suggests Belyaev was correct (Wang et al. 2018). This study identified more than one hundred genes in the prefrontal cortex of the brain that showed different gene expression patterns between domesticated and aggressive foxes. Some of those genes are linked to serotonin receptor pathways that modulate behavioral temperament, including tame and aggressive temperaments.

When Belyaev proposed that the domestication syndrome was linked to tame behavior, he did not have a proposed mechanism, but today we are getting closer to understanding how this works. Very early on in animal development, what are known as neural crest cells migrate from the neural crest to a plethora of locations: glands in the endocrine system, bone, fur, cartilage, the brain and other spots in a developing embryo. The neural crest cell hypothesis for the domestication syndrome proposes that selection for tame behavior results in a reduction of the number of migrating neural crest cells, which subsequently leads to changes in fur coloration, facial structure, the strength of cartilage (floppy ears, curly tails and so on), hormone levels, the length of the reproductive season, and more. This hypothesis may provide the link that Belyaev was missing when he came up with the idea for the experiment (Wilkins et al. 2014).


And if skull shape has an impact on the prefrontal cortex:

This study identified more than one hundred genes in the prefrontal cortex of the brain that showed different gene expression patterns between domesticated and aggressive foxes. Some of those genes are linked to serotonin receptor pathways that modulate behavioral temperament, including tame and aggressive temperaments.
 
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