Dog owners everywhere will be familiar with the big, sad eyes staring up at them as they pick up their car keys to head out or put on their coat at the door.

"It's a real sad case what happened," Keane says. ... "I still paint big eyes. In fact, they are getting bigger," says Keane. "But I think my inner feelings come out with lots of bright colors.

When a dog stares at you with big, sad, puppy dog eyes, it's easy to imagine that this adorable look is meant specifically to melt your heart (and score some treats). But new research shows that ...

So as it turns out, when your dog is giving you those big, sad eyes to beg for more treats, they’re using their evolutionary traits to their advantage.