For many pet owners, a dog isn't just a furry friend—it’s family. According to Vox, this emotional bond can be explained with science. Tens of thousands of years ago, humans and wolf dogs became hunting companions, laying the foundation for the relationship that humans later shared with domesticated dogs. As we evolved, so did our emotional connection with animals, resulting in the close kinship we share with canines today. Learn more about this evolutionary process—and why it’s so hard to say goodbye to a beloved pup—by watching Vox’s video below.

[h/t Vox]