Back in the 1950′s the then Soviet Union embarked on an ambitious project. No not the space race or the arms race of the cold war era, but on a noble quest to domesticate the silver fox. The Russian scientists selectively bred for tameness by measuring how close a wild fox would allow a human to approach. Only the tamest made it into the next generation, no biters. Surprisingly under strong selection, the desired traits began to appear quickly.

From Times Online (UK):

After a mere six generations of this selective breeding for tameness, the foxes had changed so much that the experimenters felt obliged to name a new category, the “domesticated elite” class, which were “eager to establish human contact, whimpering to attract attention and sniffing and licking experimenters like dogs”. At the beginning of the experiment, none of the foxes were in the elite class. After ten generations of breeding for tameness, 18 per cent were “elite”; after 20 generations, 35 per cent; and after 30 to 35 generations, “domesticated elite” individuals constituted between 70 and 80 per cent of the experimental population.

Not only did the foxes change behaviorally, physiological changes similar to domesticated dogs began to appear.

From Wikipedia:

The domesticated foxes exhibit both behavioral and physiological changes from their wild forebears. They are friendlier with humans, put their ears down (like dogs), wag their tails when happy, and have begun to vocalize and bark like domesticated dogs. They have also developed color patterns like domesticated dogs and have lost their distinctive musky ‘fox smell’.

More recently, a microarray analysis has shown that only a handful of genes expressed in the brain are altered by behavioral selection. Small genetic changes can have a large effect.

From ScienceDirect:

The widespread changes seen in the farmed foxes following selection for tameness have been interpreted as a model of what may have taken place during the domestication process for other mammals [4 L.N. Trut, I.Z. Pliusnina and I.N. Os’kina, An experiment on fox domestication and debatable issues of evolution of the dog, Genetika 40 (2004), pp. 794–807. View Record in Scopus | Cited By in Scopus (7)4]. Our results suggest that the striking and widespread differences between NS and S animals are accompanied by limited amount of gene expression divergence compared to that between wild and farmed animals. As the S line had been founded by a small number of individuals, founder effects might have increased the differentiation between NS and S foxes; if this were the case, however, the real effect of behavioural selection would be even smaller than that reported here. As the NS and S foxes lived in identical environments, the observed differences most probably reflect the consequences of behavioural selection, with perhaps some contribution from founder effects, whereas the differences between farm and wild animals are likely to derive from both genetic (adaptation to captivity) and environmental differences. These combined results suggest that the dramatic behavioural and physiological changes caused by selection for tameness may be associated with only limited changes in the brain transcriptome. This contrasts with studies with Drosophila melanogaster [10] which have shown that selection for behavioural traits can result in much larger transcriptome changes. Further research will help to elucidate to what extent the observed expression divergence causes tameness in the foxes, or whether it reflects down-stream alterations produced by adaptive changes to the life with humans.

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Domesticated silver fox

Selection for tameness has changed brain gene expression in silver foxes

Image courtesy SibFox.com

domestication, fox, genetics, russia, Science, USSR