In part two we looked a two hypotheses on how wolves turned into domesticated wolf/dogs.
Of the two proposed it seems likely that as wolves started living closer and closer to human settlements natural selection ended up in producing a wolf that was less and less fearful of humans. An experiment in Russia that commenced in 1959 adds weight to this as a possible answer.
Wild Silver Foxes have always been farmed for their pelts in Russia due to them being exceptionally good in keeping people warm when used in outer clothing. The problem was that as wild foxes they are particularly aggressive and very difficult to handle.
In 1959 a Russian geneticist Dmitry Belyaev was tasked with the job of making the Wild Silver Foxes tamer and therefore easier to handle.
Belyaev considered that if tamer foxes were selected and only allowed to breed with other tamer foxes that after a number of generations one may end up with a tamer Silver Fox. The method of selection was relatively simple, a gloved hand was presented to the fox in the cage, if it showed any aggression (i.e. it attacked and bit at the gloved hand) it was immediately excluded from the breeding program.
This simple method of selection was continued for generation after generation of Silver Foxes with only the tamest foxes being allowed to breed. An amazing discovery ensued, after only eight generations tamer foxes were being bred. This experiment continues to this day.
In the last few years adaptations have been made to the breeding program to determine if the aggression is in fact being bred out of the foxes (nature) or if they are simply learning to be less aggressive by their parents (nurture). To try and answer this question the researches transplanted embryos from tame foxes into aggressive foxes and vice versa. The tame foxes with the aggressive embryos implanted produced pups that were aggressive and the aggressive foxes with the tame embryos implanted produced tame pups. The researchers were able to determine with a level of confidence that aggression and tameness are therefore as a result of ‘nature’ not ‘nurture’.
What has happened as the program continued came as more of a surprise. As the foxes became tamer so their physical appearance began to change, instead of being a single dark colour they began to develop white patches, their tails began to be held a little higher and some foxes developed floppy ears. They were able to determine, that the gene that held the code for the coat colour was along the same genetic thread that held the code for the adrenaline response – which in tamer foxes was significantly reduced.
It seems that when you select for tameness a whole lot of other stuff comes along for ‘free’ – changes to physical characteristics.
We know that many ancient cultures consider the dog to have mystical, almost magical abilities. Consider that if in just eight generations in captivity Wild Silver Foxes can be tamed, what must our human ancestors have believed a wolf to be capable of – in seeing a wild wolf change, almost in front of their eyes, (certainly within a single human generation), into a tamer animal that stayed around the camp and posed little or no threat, unlike its wild cousins that lived beyond the camp.
Part 4 looks at the rise of the domestic dog and how it developed into many breeds.