Genetic Breakthroughs in Dogs

Dog domestication and genetic imprinting studies reveal new information about breeding.

By

Dogs in Review

 

In “Dogs Decoded,” a program that aired on PBS’ Nova series on Nov. 9, 2010, the science behind the close bond between humans and dogs was analyzed. One segment sought to explain how dogs, who descend from wild canids, came to trust and love man so unquestioningly. As it turns out, this could have happened in a much shorter time frame than previously imagined. Listen to this...

In 1959 Soviet scientists set up a breeding program in Novosibirsk to see if they could domesticate silver foxes, selected from local fur farms. The experiment still continues today, overseen by Dr. Lyudmila Trut. The foxes were “temperament tested” — most were either aggressive or fearful, but about 1 percent showed signs of neither fear nor aggression. This 1 percent was selected to become the founding generation of a new population of foxes.

At every generation, the process was repeated, so only the tamest foxes were allowed to breed. Within just three generations the aggressive behavior in the offspring began to disappear. The radical changes came in the eighth generation, when foxes started to seek contact with humans and show affection for them. Cubs that had just started to crawl opened their eyes and started showing affection to humans, wagging their tails, etc. Half a century and nearly 50 generations later, the foxes are tamer than ever. This is an accelerated model of how dogs may have been domesticated from wolves.

The scientists also experimented with cross-fostering, placing aggressive cubs with tame mothers and vice versa. They found that the mother’s behavior did not influence that of the cub: the genetically “wild” cubs stayed aggressive, the tame ones remained affectionate. In other words, the difference between tame and aggressive foxes is almost entirely genetic.

According to Dr. Trut, “If foxes were brought up in a domestic environment [...] they would make fantastic pets!”

An even more surprising result of the experiment was that, as the foxes’ behavior changed, so did their physical appearance. Just a few generations into the experiment, scientists noted that the coat patterns changed dramatically in some tame foxes; tails often became curly instead of straight, ears began to flop, and limbs and tails were shorter. In effect, although no selection for these changes was made, the foxes also began to look more like dogs at the same time as their temperaments became “tamer.”

What the above means for dog breeders I’ll leave for you to think about, but it’s interesting to consider that it may have taken a much shorter time for the dog to become domesticated than is commonly thought, and that some of the conformation features simply came along without any selection.

Another perhaps even more important genetic breakthrough was presented in a Newsweek article dated Nov. 8, 2010. Scientists at Washington State University have discovered that life experiences of parents may alter their eggs and sperm so indelibly that the change is passed on to children, grandchildren and beyond. This is of course the opposite of what we’ve always been told — that acquired characteristics are not inheritable.

Other labs around the world have found the same thing: the conditions a lab animal lives in, a person smoking, being malnourished in childhood, or overeating — all leave an imprint on eggs and sperm that affects children, grandchildren and possibly further generations also.

So if a man overeats in childhood, his children are four times more likely to develop diabetes and cardiovascular disease, according to these studies. The research is still in the early stages, but if the findings — as expected — are also applicable to dogs, this will shake the very foundation of what we dog breeders thought we knew.


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