The Woof at the Door

Dogs are descended from wolves, probably the gray wolf. Some scientists argue that, because dogs and wolves can and do interbreed, they shouldn’t be considered to be separate species at all. They believe that domestic dogs are only a subspecies or variant of the gray wolf, Canis lupus, and ought to be called Canis lupus familiaris (the familiar or domestic wolf) instead of Canis familiaris (the familiar or domestic dog). Although the ability to interbreed and produce fertile offspring is a triedand-true criterion for recognizing that two populations are really variants of a single species, the reality is more nuanced. We cannot know whether dog-wolf hybrids will thrive and survive, or die out, in the long run.