When a beloved dog, whatever its breed, dies, we seek to find another just like him. So we go to a breeder and buy a replica. By doing so we convince ourselves that our departed dog continues to live in the soul of the new one. We think we have purchased his immortality. But we haven’t.

Purebreds represent neither dogs’ past nor their future. As geneticist Richard Dawkins tells us, genes are nearly “immortal.” So those of purebreds are no older than those of mongrels. A dog’s true connection with the past lies in his character and abilities, not his genes. For millennia, dogs were defined by the jobs they did, and crossbred to ensure they would continue to perform them well. When the rural people who created these jobs disappear, dogs lose this past, and attempts to freeze their shapes in time through inbreeding do not preserve it. They merely rob dogs of a future.

Purebreds can be saved only by opening their stud books. Just as the meek shall inherit the Earth, so lowly mixed breeds, including perhaps the few remaining crossbred Jack Russells, represent the future of dogs.

This article is an adaptation from the author’s new book, We Give our Hearts to Dogs to Tear: Intimations of Their Mortality (Transaction Publishers), a memoir of the Chase family’s 32 years in Montana, which they shared with successive generations of Jack Russell Terriers. The book considers the mortality of, and connections between, the land and dogs: how suburbanization and declines in land stewardship threaten the former, and indiscriminate inbreeding by show dog breeders imperils the latter.