Shepherd Wrote:The most fascinating thing was the way that they began looking more dog-like as they became domesticated.

Quote:Belyaev and his colleagues thus selected the foxes that exhibited the
least fear/shyness of people for their breeding program; their aim was
to selectively breed for the tame trait. With successive generations of
selective breeding the foxes became tamer and tamer such that by the
eighteenth generation they had bred a fox that exhibited all the
characteristics of a domestic dog. The foxes would actually approach
people, clamber over them, roll over to get their bellies tickled and
even answered to their names.

Perhaps the most surprising aspect of the selective breeding program was
that the foxes no longer resembled foxes but looked and acted like
dogs. The coats of the foxes were no longer the characteristic silver
fur much sought after by the fur industry but were black and white
piebald instead. What is more, the foxes' tails were curly and upward
turned, their ears were floppy and to crown it all the animals even
barked like dogs! Dmitri Belyaev had not sought nor bred for these
characteristics but all the same they still manifested!

A subsequent investigation into the unexpected side effects revealed
that breeding for tameness set off an entire cascade of hormonal changes
in the animals. It was observed that the "domesticated" foxes had
considerably lower levels of adrenaline which explained their tameness
(reduction in flight-or-fight reflex) but didn't explain the other
observed changes. However it didn't take long before Belyaev and his
colleagues made the connection; the hormone adrenaline shares a
biochemical pathway with melanin, a hormone that plays a significant
role in an animal's coat color.

Simply put, selective breeding for the tameness trait set off and
stimulated an entire slew of genetic changes within the animals in a
surprisingly short period. It is now widely believed that the wolf
underwent a similar transition to eventually evolve into the domestic
dog.