“The separation from the owner for the dog is not voluntary,” says Vallortigara. “It is always unnatural for a dog to detach and abandon the pack.” Dogs will sometimes go solo on a temporary basis if they’re sufficiently motivated to do so, but they do it knowing that social contact can be resumed at virtually any time. “The exaggerated level of greeting that can be observed in some dogs is likely due to the fact that they have not yet learned to accept the possibility of non-voluntary detachment,” says Vallortigara. When trying to appreciate a dog’s over-the-top greeting, Hekman says we need to imagine what it was like for a dog to be alone all day while we were gone.
“This dog probably had a pretty boring day without much enrichment, and moreover may have been alone all day, which is unpleasant for a social animal,” she told io9. “So in addition to being glad to see us, they are probably feeling some relief that they will get to do something interesting, like go for a walk, and have someone else around. Some people are able to have a dog walker come in or send their dogs to daycare—this is a great solution to what can otherwise be a difficult lifestyle for a dog.”
And as Berns points out, the greeting ritual is a social bonding mechanism—but it’s also a function of curiosity.
“When they jump up, they’re trying to lick you in the face,” says Berns. “Part of that is a social greeting, but they’re also trying to taste and smell you to figure out where you’ve been and what you’ve done during the day. So some of it is curiosity. If I’ve been with other dogs, for instance, my dogs know it, and they resort to sniffing intensely.”