Belyayevs Silver Foxes

In this post we will be looking at some of the physiological changes of a specific Silver Fox population during a Soviet Taming program, headed by Dmitry Belyayev.

Evolution and Genetics where hot topics and politically charged right through to the middle period of the Cold War with the Iron Curtain dividing scientific knowledge and leading to a distillation of Warsaw Pact and NATO treaty scientific research centres. One side of the curtain was firmly grounded in Darwin’s theory of natural selection which pointed towards the field of gene research whilst the other was based on Lysenkos debunked political agenda for agrarian production despite genetics.

None of this is important to us…except that shortly after Stalins death a Soviet scientist, Dmitry Belyayev gained support from the Soviet leader Krushchev, whose daughter appears to be pro-genetics, based upon her journalism. So he was able to work on his isolated population of silver foxes and gather data as the population was artificially selected for tame temperaments. The creation of pet silver foxes, ultimately.

In looking further into the results we can see that the population was being filtered towards neoteny. Neoteny is when an animal retains juvenile characteristics into adulthood. The axolotl is an example of an amphibian that retains a juvenile state for life. A tadpole like salamander.

Looking more towards the end goal what we will see develop in Belyayevs colony is that they will resemble odd coloured silver fox puppies – fox juveniles are called kits.

Here is a timeline of the changes that could be observed in the colony at specific stages:

After 8 generations the coat of the silver foxes tended toward a piebald or particoloured coat, similar to goats, cows, horses, pigs and rabbits. This was found to be produced at a much higher frequency than in wild

Soon thereafter, ears became floppy, tails rolled up, vertebrae became truncated very similar to the domestic dog today.

After 12 generations the corticosteroid level of the tame colony was found to be around half of the control group, which was left as unchanged as possible.

This steroid is naturally produced in the mammalian body and dictates macro (protein, carbohydrate and fat) and micro (vitamins and minerals) metabolism, immune system, stress hormone production efficiency and many other functions.

After 15 generations the population exhibited early signs of further physical change in that tails became shorter as did the legs, over and underbites also formed. Interestingly, this population also displayed their fear response many weeks after the control group. Again, this appeared to be linked to the changes in corticosteroid levels, the data would suggest that this level change allowed for a decreased distress state benefiting the animal’s ability to adapt to stress. This may indicate a larger window of opportunity to socialise with humans positively.

After 28 generations the corticosteroid level had halved again and congruently the serotonin level had increased. Seratonin is believed to be a contributing factor to feelings of well-being and happiness, it also regulates mood, sleep and appetite. Further Seratonin is believed to have a marked effect upon cognitive functions. Particularly memory and learning.

At the same stage it was also observed that male fox skulls where changing shape to be more narrow and similar in appearance to female skulls. Also, litter produced by the experimental group tended to be larger.

After 40 generations Belyayev had created a tame colony of silver foxes which who 'displayed behavioural, physiological, and anatomical characteristics that were not found in the wild population, or were found in wild foxes but with much lower frequency’ Even their body odour had become more palatable. Let us refer this information back to our dogs, if we are selecting for good temperaments and biddable or pro-social dogs we are filtering towards juvenile behaviours, since behaviours are linked to genetics which are inherited as are physical traits.

This indicates to the reason for wolves being much larger than domestic dogs, aggression in dogs being greatly reduced – as a frequency of occurrence in a population – as juveniles tend to be less aggressive than adults and juvenile behaviours remaining present in adult domestic dogs. Juvenile behaviours such as whining, barking and submissiveness also remain present in our pets as a package of these behaviour types.

As does the behaviour of face licking, a behaviour that pups employ to instigate the dams regurgitation reflex and yield solid food once the pups are weening. Face and hand licking remain a part of our dogs repertoire of behaviours for life, however the frequency is greatly reduced in wolf populations.

This is an important step in understanding the natural proclivity towards certain behaviours in our dogs. If we can accept that these behaviours are normal, we can start to accept our dogs for what they are. They are not juvenile or paedomorphic wolves, they are an animal unto themselves shaped by artificial selection.

While we can affect elicited behaviours through training – keep your tongue away from my face - it is important to understand the nature of our dogs and where they come from.

In particular, a behaviour pattern that is no longer required for the vast majority of dogs is the predatory sequence. Whilst certain breeds of dogs have had their predatory sequence modified – think Cattle and Sheep dogs, Sight and Scent hounds, Jack Russel Terriers, whose sequence have been modified to meet a purpose and compare them to the toy breeds such as Shih Tzu, Poodle and King Charles Cavaliers who have had their predatory behaviours diluted through the generations to the point of effectual uselessness – others have had their emotional responses altered, think of Protection/Guard dogs and Livestock guardians.

Below I have included a picture of an adult silver fox and one of the Belyayev adult foxes. Lastly I have included a picture of a silver fox kit, if you’re like me you will see the resemblance between the adult Belyayev fox and the silver fox kit.

Adult Silver Fox - Adult Belyayev Silver Fox

Juvenile Silver Fox

Also I have included a picture of a Gray Wolf in profile and an Alaskan Malamute in profile, note the shortened legs and corn cob style body of the Malamute compared to the Gray Wolf, the tail is curled, the ears rounded. All of the data that Belyayevs experiment gathered about the Silver Foxes can be seen in our dogs too. And while aggression levels vary from one animal to the next, the propensity of the occurrence is greatly reduced in the domesticated canid.