Can your full-grown dog still recognize her mother? An interesting experiment reveals the answer!
Last fall, I was at a gathering of emeritus faculty members at my university. At one point during the conversation, one of my colleagues posed an interesting question. “I’m going to visit my dog’s breeder this weekend,” she said, “and my husband and I were debating whether Siegfried [her Labrador Retriever] will recognize his mother, Ashley. I was wondering if any of you behaviourally-knowledgeable people have an opinion?”
The first response came from a behavioural biologist, who mused, “Well I can’t imagine that the DNA of dogs has changed all that much from the DNA of wolves. The social hierarchy in a wolf pack is really based on family structure — the parents hold the highest status and are the pack leaders. That means that the pups must have an inherited ability that allows them to recognize and remember their mother simply because, for the pack to function well, she must be obeyed. I wouldn’t be surprised if that recognition of their parents also comes with a sense of kinship and affection. On the flip side, the mother should recognize her own offspring since she has gone through a period of rearing them when her whole focus was on guarding, nourishing, and protecting the pups.”
A social psychologist in our little group disagreed. She argued, “While it may be the case that family structure and recognition of kinship is necessary for wild canines, it’s not the case with domestic dog litters. Our dogs don’t stay in a family grouping for long, but rather, after only a couple of months, the litter is generally disbanded as puppies go to their new families. After that, the majority of pups will never see their parents again.”
Then she added an interesting twist to her argument, saying, “I am also struck by the fact that there are some behaviours which seem to be incompatible with the idea that the dogs do recognize their mothers. In particular, it seems to me that dogs demonstrate that they lack any recognition of their biological relatives by violating basic social-psychological principles. When my dog was about three years of age, he met his mother again. Although he seemed happy to see her, in less than half an hour he was trying to mate with her! It seems to me that this is something which he certainly would not do if he recognized her as his mother.”
Study reveals puppy preferences
Another faculty member in the group asked if I had run into real empirical data that could answer this question.
In fact, I did recall a convincing set of experiments that were done just a little while back by Peter Hepper, from the School of Psychology at Queens University of Belfast, in Northern Ireland. It involved a number of litters of puppies and their mothers (multiple sets of Labrador Retrievers, Golden Retrievers, and German Shepherds). At the time of testing, the pups were aged between four and five-and-a-half weeks of age.
To assess whether these young puppies would recognize their own mothers, two wire enclosures were placed at the end of a room. A puppy’s mother was placed in one, while a female dog of the same age and breed was placed in the other. The puppy would enter at one end of the room and the experimenter recorded which of the areas he went to first, and how long he spent attending to the dog in that enclosure. The results were unambiguous, with 84% of the puppies preferring their own mothers.
The second experiment wanted to determine whether these young pups recognized their brothers and sisters. So the investigators modified the situation by placing puppies from the test pup’s own litter in one of the enclosures, and puppies of the same breed, age, and gender in the other. Again the pups showed recognition of their own relatives by preferring their siblings 67% of the time.
Scent plays crucial role in helping dogs recognize other dogs
Hepper went on to show that scent cues played an important role in helping the test puppies recognize their biological family members. He did this by repeating the experiments — only now, instead of having an actual live dog in each of the wire pens, he used a large square of towelling cloth that target dogs had slept on for two days. The results were very similar to the previous experiments. When pups were given a choice of a cloth impregnated with their mother’s odor, versus one impregnated with the odor of a similarly aged, unfamiliar female of the same breed, 82% showed a preference for the scent of their mothers. When pups were given a choice between a cloth impregnated with their siblings’ odor, compared to one impregnated with the odor of a dog of similar age and breed but from a different litter, 70% showed a preference for the scent of their littermates.
The results of these two experiments clearly show that young puppies recognize their own mothers and littermates, and it also shows that this recognition is based upon scent cues.
What happens when puppies grow up?
However, the question my colleague raised was whether or not, when the pups grow into adult dogs, they will still recognize their biological mothers. This indicates that the tests should be done on adult dogs rather than young puppies. To do this, Hepper gathered a set of dogs that were approximately two years of age. These dogs had been separated from their mothers when they were around eight weeks old, and had never seen them since. He now repeated the previous set of experiments starting with an assessment of whether the mothers still recognized their offspring after all this time apart, based upon scent alone.
The results were quite clear, with 78% of the mothers sniffing the cloths containing the scent of their offspring longer than they sniffed the scent of unfamiliar dogs of the same breed, age, and gender. So obviously, canine moms recognize their offspring even after they are adults, and after a long separation.
To see whether the offspring still recognize their mothers, the experiment was now revised so that the targeted scent was that of the dog’s mother compared to another female dog of the same breed and age. The results were almost the same as in the case of the mothers recognizing their offspring, with 76% of the dogs showing a preference for the cloths impregnated with their mothers’ scent. This was impressive because these adult dogs had not seen their mothers for around two years.
While Hepper’s research proves a dog can remember his mom after a long separation, it does not tell us how a male dog will act around his mother once they are reunited. Contrary to the beliefs of my social-psychological colleague, a male offspring behaving amorously toward his mother during their reunion should not be taken as evidence that he has failed to recognize her as his parent.
In humans, a romantic relationship between a mother and her son has been culturally determined to be taboo. Scientific evidence shows that offspring resulting from a physical relationship between close relatives can often result in the appearance of physical and mental problems due to the pairing of otherwise recessive genes, so it is forbidden in our society.
However, dogs are not humans. They don’t live by our moral code nor do they know about the data explaining why this type of relationship is bad from a scientific perspective. For them, it’s just biology.
The cool takeaway here is that dogs can recognize family members, even after a long separation. To put this in perspective, that would be like a two-and-a-half –year-old human toddler being separated from his mother or siblings, and then recognizing them when he sees them again at age 25.
Stanley Coren is professor Emeritus in the Department of Psychology at the University of British Columbia. He is also an award winning behavioural researcher, a Fellow of the Royal Society of Canada, and was named as one of the 2,000 outstanding scientists of the 20th century. His many books on dog behaviour and human-canine interactions have been international bestsellers. His awards include the prestigious Maxwell Medal of Excellence from The Dog Writers Association of America for his book Born to Bark. Coren has been featured on Oprah, Larry King, and can be heard broadcasting a radio column on CBC. His newest book is Do Dogs Dream.