Study: dogs evolved from extinct species of wolf


WASHINGTON, January 17, 2014—A recent study finds that even though dogs may have evolved from wolves, dogs’ early ancestors are probably extinct.

“Dog domestication is more complex than we originally thought,” said John Novembre, University of Chicago geneticist and senior author of the study.

In the study published Thursday in the journal PLOS Genetics, researchers generated genome sequences for three gray wolves from China, Croatia, and Israel, the three possible areas where dogs were believed to have been domesticated.

The research team also generated a genome sequence for two dogs believed to be isolated from modern wolf populations, the dingo and the basenji. Finally, they included the genome sequence of a golden jackal to represent earlier divergence, and the previously published genome of a European boxer.

Scientists expected to find one of the lines of gray wolves to be genetically closer to modern dogs when comparing their DNA sequences. Surprisingly, however, none of the gray wolf lines was more closely related to dogs than the other.

“Perhaps the closest lineage of wolves to dogs went extinct and is not represented well by modern wolves,” said Novembre.

In a re-evaluation of previous beliefs about dog origins, study authors hypothesize that domestication separated wolves and dogs sometime between 11,000 and 16,000 years ago. During domestication, dogs went through what scientists call a “domestication bottleneck” that reduced their population by 16-fold. Soon after, wolves also went through a similar bottleneck that reduced their populations significantly.

“A sharp bottleneck in wolves occurred soon after their divergence from dogs, implying that the pool of diversity from which dogs arose was substantially larger than represented by modern wolf populations,” said the study authors.

According to the study, the results of genome analysis suggest that dogs may have come from a lineage of wolves that was eliminated by the bottleneck in the wolf population.

By narrowing the date range for initial dog domestication to between 11,000 and 16,000 years ago, which predates the rise of agriculture, study authors bolster previous research suggesting that dogs were initially domesticated by hunters as companions and not by farmers, as formerly believed.

By analyzing amylase genes, which promote the digestion of starch, the study confirms earlier studies suggesting that dogs developed the ability to digest starch as they adapted to living with humans.

However, Novembre and his team found that while most dogs have high numbers of amylase genes to promote starch digestion, the fact that dingoes and Siberian huskies lack these genes suggests that dogs only adapted to a starchy diet if it was necessary.

While the analysis of the wolf genome suggests a bottleneck in the wolf population shortly after the divergence from dogs, the cause of the bottleneck is unknown. Nevertheless, researchers were able to determine that it occurred before any human extermination campaigns, but “within the timeframe of environmental and biotic changes associated with the ending of the Pleistocene era.”

So, what kind of wolf did your dog evolve from?

“The common ancestor of dogs and wolves was a large, wolf-like animal that lived between 9,000 and 34,000 years ago,” said Robert Wayne, co-senior author of the study, to Discovery News. “Based on DNA evidence, it lived in Europe.”

Laura Sesana is a writer and DC, MD attorney. Follow her on Facebook, Twitter @lasesana, and Google+.

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