Posted Date: March 4, 2013
A new study reveals that 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. With wolf pups, it takes 24 hours! By Claudia Bensimoun
Dogs and wolves are so similar genetically, yet it's been difficult for biologists to understand why wolves remain wild while dogs will easily become domesticated. But now a new study finds that early developmental differences between wolves and dogs and the changes in their developmental timing may play an important role in the behavioral differences between adult wolves and dogs. The study, presented this year by evolutionary biologist Kathryn Lord at the University of Massachusetts Amherst, finds the different behaviors are related to the animals' earliest sensory experiences and the critical period of socialization.
Little was known about the sensory development in wolf pups, and beliefs about the timing of their sensory development were usually gathered from studies on dogs, since wolves and dogs are two subspecies of Canis lupus. Nonetheless, early developmental differences between these two subspecies have already been identified, Lord explains. Earlier research found that wolves tend to approach and investigate objects around them two weeks before dogs do. Lord also discusses the timing of the ability to walk as one of the most important developmental factors. These changes in developmental timing may play an important role in the behavioral differences between adult wolves and dogs.
In this study, which compared the development of the sensory systems in wolves and dogs, Lord studied responses of seven wolf pups and 43 dog pups to both familiar and new smells, sounds, and visual stimuli. This was tested weekly from two to seven weeks of age. Eleven wolf pups were also observed for orientation towards auditory and visual stimuli during two-hour sessions, five days a week, from two to eight weeks of age. Researchers recorded all these observations and found that wolves and dogs did develop their senses at the same time. The study revealed new information about how wolves and dogs experience their environment during a four-week developmental window known as the "critical period of socialization." These new facts may significantly change the understanding of wolf and canine development.
When the socialization window is open, both wolf and dog pups begin walking and exploring their environment without fear and will retain familiarity throughout their lives with those things that they come into contact with. Domestic dogs can be introduced to humans, cats, and even horses at this stage and still be comfortable with them forever. Yet as the period progresses, fear increases and after the socialization window closes, new sights, new sounds, and smells will elicit a fear response.
A wolf pup explores his environment. Photo courtesy of Anne-Marie Arnold.
Lord confirmed that both wolf pups and dog pups develop their sense of smell at two weeks of age, hearing at four weeks, and vision by six weeks, approximately. Nonetheless, both of these subspecies enter the critical period of socialization at different ages. Canine pups will begin this process at four weeks, while wolves will begin this period of socialization at two weeks. How each subspecies experiences the world during that most important month is extremely different, and likely leads to very different developmental paths, says Lord.
The research added for the first time that wolf pups are still blind and deaf when they begin to walk and 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," says Lord in the online article UMass Amherst Study May Explain Why Wolves are Forever Wild, But Dogs Can Be Tamed. "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," she adds.
Dog pups only begin to explore and walk after all three senses, 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. 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," says Lord.
Lord says she finds that these significant, development-related differences in dog and wolf pups' experiences put them on distinctly different trajectories in relation to the ability to form interspecies social attachments, most of all with humans. Lord suggests that this new information has implications for managing wild and captive wolf populations.
Lord's experiments analyzed the behavior of 11 wolves from three litters and 43 dogs. Of the dogs used, Border Collies and German Shepherds which were raised by their mothers were included, as well as a control group of 10 German Shepherd pups which were hand-raised (a human was introduced to these pups soon after birth).
Lord finds that at the gene level, "The difference may not be in the gene itself, but in when the gene is turned on. The data helps 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 the age of three weeks, and even then you won't get the same attachment or lack of fear," she says.
Claudia Bensimoun is a freelance writer in West Palm Beach.