January 18, 2013
Study Determines Why Dogs Can Be Tamed, While Wolves Remain Wild
April Flowers for redOrbit.com - Your Universe Online
Dogs and wolves are genetically very similar, which has made it difficult for scientists to understand why dogs are happy to become "man's best friend" while wolves remain fiercely wild. Kathryn Lord, doctoral student at the University of Massachusetts Amherst, suggests the different behaviors are related to the animals' earliest sensory experiences and the critical period of socialization.
Previous to this study, little was known about the sensory development in wolf pups. Most assumptions, therefore, were extrapolated from what is known of dogs. Scientists already know that there are significant early development differences in the two species, making this assumption problematic. The chief difference is the timing of the ability to walk, Lord said.
Lord studied the responses of seven wolf pups and 43 dogs to both familiar and new smells, sounds and visual stimuli to address this knowledge gap. She tested the animals weekly, finding that they did develop their senses at the same time.
Her study, published in the current issue of Ethology, revealed new information about how the two subspecies of Canis lupus experience their environment during a four-week developmental window called the critical period of socialization. The understanding of wolf and dog development may significantly change with these new facts.
During the socialization window, both wolf and dog pups begin walking and exploring without fear. They will retain familiarity throughout their lives with those things they contact during the explorations. For example, dog pups can be introduced to humans, horses and cats at this stage and they will be comfortable with them forever. As the socialization period progresses, however, fear increases and after the window closes, new sights, sounds and smells will elicit a fear response.
Lord confirmed that both wolf and dog pups develop the sense of smell at two weeks of age, hearing at four weeks, and vision by age six weeks on average. The two species enter the socialization window, however, at different times; dogs begin at four weeks, while wolves begin at two weeks. This leads to extremely different experiences during the critical month of socialization, leading to different developmental paths.
For the first time, scientists now understand that wolf pups are still blind and deaf when they begin to explore their environment at two weeks of age.
“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 noted in a statement. “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. As each sense engages, wolf pups experience a new round of sensory shocks that dog puppies do not.”
Dog pups, on the other hand, only begin to explore and walk after all three senses 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. A litter of dog puppies at two 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.”
Dog and wolf pups' significant development-related differences put them on distinctly different trajectories in relation to the ability to form interspecies social attachments, most notably with humans. The findings of this study have implications for managing wild and captive wolf populations.
The animals in this study consisted of 11 wolf cubs from three litters and 43 dog pups in total. 33 German shepherds and border collies were raised by their mothers, and 10 German shepherds were hand-raised by humans as a control group.
Lord explained that at the genetic level “the difference may not be in the gene itself, but in when the gene is turned on. The data help to explain why, if you want to socialize a dog with a human or a horse, all you need is 90 minutes to introduce them between the ages of four and eight weeks. After that, a dog will not be afraid of humans or whatever else you introduced. Of course, to build a real relationship takes more time. But with a wolf pup, achieving even close to the same fear reduction requires 24-hour contact starting before age three weeks, and even then you won´t get the same attachment or lack of fear.”