Why Dogs, Unlike Wolves, Can Be Tamed

Researcher finds differences in critical socialization period.

THURSDAY, Jan. 24 (HealthDay News) -- Differences in dogs' and wolves' sensory and socialization experiences when they are puppies explain why one is easily tamed and the other remains wild, according to a new study.

Dogs and wolves are genetically close but little has been known about sensory development in wolf pups. It was widely assumed that they were much like dogs in that regard. This new study shows otherwise.

Kathryn Lord, an evolutionary biologist at the University of Massachusetts, Amherst, studied the responses of seven wolf and 43 dog pups to familiar and new smells, sights and sounds. She focused on a four-week developmental phase called the critical period of socialization, when the pups begin walking and exploring their environment.

During this stage, dogs can be introduced to people and other animals and things and will be comfortable with them for the rest of their lives. The same is true for wolf pups in their environment. But when this stage is over, new sights, sounds and smells will trigger fear.

The findings, published in the February issue of the journal Ethology, could prove useful in managing wild and captive wolf populations, Lord said.

Lord confirmed that both wolf and dog pups develop the sense of smell at an average of 2 weeks of age, hearing at 4 weeks and vision by 6 weeks. Wolves, however, begin the critical period of socialization at 2 weeks while dogs begin it at 4 weeks.

Wolf pups are still blind and deaf when they begin to walk and explore their environment at 2 weeks, Lord discovered.

"No one knew this about wolves, that when they begin exploring they're blind and deaf and rely primarily on smell at this stage, so this is very exciting," Lord said in a university news release.

"When wolf pups first start to hear, they are frightened of the new sounds initially, and when they first start to see they are also initially afraid of new visual stimuli," Lord explained. "As each sense engages, wolf pups experience a new round of sensory shocks that dog puppies do not."

Dog pups only begin to explore and walk after their senses of smell, hearing and sight are functioning.

"It's quite startling how different dogs and wolves are from each other at that early age, given how close they are genetically," Lord said. "A litter of dog puppies at 2 weeks are just basically little puddles, unable to get up or walk around. But wolf pups are exploring actively, walking strongly with good coordination and starting to be able to climb up little steps and hills."

She said these significant differences in dog and wolf pups' development and experiences make a major difference in their ability to form attachments to other species, notably humans.

More information

The San Diego Zoo has more about wolves.