Literature Review: Wolves and Dogs

by Carl Strang

Last year produced a few published studies of wolves and dogs that caught my eye. Dogs are well established as having been domesticated from wild wolves, but the timing and nature of that new relationship have been a contentious topic. Here is a recent contribution to the debate:

Thalmann, O., et al. 2013. Complete mitochondrial genomes of ancient canids suggest a European origin of domestic dogs. Science 342:871-874. This group of researchers previously had suggested that dogs first were domesticated in the Middle East, but this new study with updated methods points to a European origin 18-32,000 years ago. They included DNA from fossil wolves and dogs in their comparisons. From an interpretive article in ScienceDaily: “By comparing this ancient mitochondrial DNA with the modern mitochondrial genomes of 77 domestic dogs, 49 wolves and four coyotes, the researchers determined that the domestic dogs [of today] were genetically grouped with ancient wolves or dogs from Europe — not with wolves found anywhere else in the world or even with modern European wolves. Dogs, they concluded, derived from ancient wolves that inhabited Europe and are now extinct.” This timing and geography point to a likely domestication by hunter-gatherers rather than agriculturalists.

Wolf at Wolf Park in Indiana

Wolf at Wolf Park in Indiana

Once the ancestors of dogs had become genetically isolated from wolves, the two populations were exposed to different selective pressures. The wolves continued to be subject to natural selection, while the dogs were influenced by human-directed selective breeding, and by the different selective pressures of living in human communities. The next study compared the development of dogs and wolves, and discovered some consequences of that divergence.

Kathryn Lord. A Comparison of the Sensory Development of Wolves (Canis lupus lupus) and Dogs (Canis lupus familiaris). Ethology, 2013; 119 (2): 110 DOI: 10.1111/eth.12044 From a ScienceDaily article. She looked at the relationship between the timing of sensory maturation and exploration behavior in wolf and dog puppies. Both acquire smell, hearing and vision in that order, at 2, 4 and 6 weeks of age. Wolves, however, begin exploration and socialization at 2 weeks, dogs at 4 weeks, and so dogs are socializing after they have the ability to perceive their social surroundings more completely. Wolves are getting fearful shocks during this period as new sensory capabilities appear, and so need an earlier and more complete contact with their social community, and never form the same kind of solid bond that dogs do.

Dogs have diverged from their wolf ancestors

Dogs have diverged from their wolf ancestors

A final, sadder note was a news article in Science magazine that explained how Isle Royale’s long-studied wolves are close to dying out.

Wolf tracks on an Isle Royale beach. Are these about to disappear?

Wolf tracks on an Isle Royale beach. Are these about to disappear?

Mlot, Christine. 2013. Are Isle Royale’s wolves chasing extinction? Science 340:919-921. Last year, for the first time in 40 years, there were no wolf pups on the island. The 2013 January count turned up only 8 closely related adults. Rolf Peterson, principal wolf biologist at Isle Royale for many years, thinks they now will die out, with inbreeding the root cause. Moose have increased as their principal predators have declined. The Park Service is considering whether to introduce new wolves to rescue the population (Isle Royale is a national park in northern Lake Superior).

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