A VERY CUNNING PLAN...

Humans first domesticated dogs around 15,000 years ago. Cats and sheep were next and over the centuries some 20 other animals came to be tamed. This represents a tiny fraction of the number of species on the planet, and biologists have devoted a lot of time to asking why. Why a horse, for instance, but not a zebra?

In the autumn of 1952, a brilliant geneticist from the then Soviet Union called Dmitry Belyaev set in train a daring, far-reaching experiment to try to answer that question.

It was daring not only on account of its intellectual boldness but also because genetics in the era of Josef Stalin was a taboo subject, and it was far-reaching because it was to lead to remarkable new theories about the process of evolution itself.

The experiment was to test whether wild foxes could be transformed into tame household pets and it was to succeed beyond Belyaev’s wildest dreams.

The default response of an Arctic silver fox when confronted by a human is to behave aggressively, yet after only a few generations of selective breeding, Belyaev’s team succeeded in producing pups that acted just like dogs. These pups would wag their tails when people walked into a room, they would roll on to their backs and offer their tummies to be stroked, and they would even bark when they felt that a favourite human was threatened. How had this happened?

The established wisdom held that evolution only occurred achingly slowly through genetic mutation, but Belyaev believed that certain hormones could trigger gene activity without mutation, part of a process he described as ‘destabilising selection’. It’s an insight that has radically enhanced our understanding of Darwinian science.

This is a fascinating story, coauthored by Belyaev’s long-term research partner Lyudmila Trut.

Belyaev’s intention was to solve an old puzzle, but his extraordinary experiment, which still continues to this day, has opened up exciting new fields of scientific inquiry.

The silver foxes have shed light not just on their own evolutionary processes but ours, too. And it’s impossible to look at the photographs of these adorable creatures without feeling a sense of wonder.

‘Within a few generations of breeding, the fox pups were acting just like dogs’