Each year, millions of dogs enter shelters where many of them, if they're lucky, get adopted by new owners. Likewise, every year outside of shelters, many dogs get handed down and passed along to new owners, whether because of hardship or inconvenience to the owner. New owners may wonder whether their adopted dogs remember previous owners, and the answer is: It depends on the dog, but anecdotal evidence seems to suggest they do.
Anecdotal evidence supports the idea that dogs do remember previous owners. Argos, as told in Homer's classic, The Odyssey, waits 20 years for his master, Odysseus, to return finally from his worldly travels. As soon as the dog recognizes his long-lost master, he has strength only to drop his ears and wag his tail, and then dies. True, it's a sad story, but it has become a strong metaphor for the faithfulness of dogs.
Patricia McConnell, PhD, and author of several books about dog behavior, says it seems reasonable that dogs have some sense of time. As proof, she cites a study published in Applied Animal Behavior Science that found that the longer dogs are left alone, the more intense they greet their owners. So time -- even 20 years in the case of Argos! -- doesn't seem to affect a dog's memory of relationships, past and present.
Humans, unlike dogs, have a concept of time known as "episodic memory," using artificial measures of time, like seconds, minutes, and hours, to distinguish events. Also, we tend to remember when something happened by relating it to other events. Dogs, on the other hand, can tell how much time has passed only since the event happened. Still, that doesn't mean dogs can't remember the past, or people from the past.
Dogs remember for other reasons, too. It's commonly believed they remember what they need to in order to survive, or because of fear. Dogs remember past unpleasant or dangerous circumstances to avoid having similar situations in the future. Finally, a type of survival memory is connected to remembering friends, owners, and those people with whom dogs generally feel safe and can trust. Therefore, if a previous owner was kind, the dog may well remember him.
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